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OBJECTIVE. The purpose of this study was to perform quantitative and qualitative evaluation of a deep learning image reconstruction (DLIR) algorithm in contrast-enhanced oncologic CT of the abdomen...

OBJECTIVE. The purpose of this study is to determine the degree of the relationship between perfusion CT (PCT) parameters and iodine concentration metrics derived from triple-bolus dual-energy CT (DECT) and to compare the radiation dose delivered. SUBJECTS AND METHODS. This single-center prospective study was conducted from October 2015 to September 2017. Twenty-three consenting adults (15 men and eight women; mean [± SD] age, 56 ± 13 years [range, 25-78 years]) with renal cell carcinomas underwent consecutive PCT and triple-bolus DECT examinations. Triple-bolus DECT consisted of synchronous corticomedullary, nephrographic, and delayed phase scans acquired using a dual-source DECT scanner. Two readers independently analyzed blood flow, blood volume, and permeability, as measured by PCT, and iodine density and iodine ratio, as measured by triple-bolus DECT. Size-specific dose estimates were calculated for both groups. RESULTS. Interreader agreement was good for permeability (intraclass correlation coefficient [ICC] =.812) and blood flow (ICC = 0.849) and excellent for blood volume (ICC = 0.956), iodine density (ICC = 0.961), and iodine ratio (ICC = 0.956). Very strong positive correlations were found between blood volume and iodine density (p < 0.001) and between blood volume and iodine ratio (p < 0.001). Strong positive correlations were found between blood flow and iodine density (p < 0.001) and between blood flow and iodine ratio (p < 0.001). The correlations between permeability and iodine density (p = 0.01) and between permeability and iodine ratio (p = 0.02) were moderate. The mean size-specific dose estimate of triple-bolus DECT was approximately 15 times lower than that of PCT (p < 0.001). CONCLUSION. Quantitative iodine metrics derived from triple-bolus DECT showed significant correlation with CT parameters in renal cell carcinoma, with a significantly lower radiation dose.

OBJECTIVE. This study aims to compare the diagnostic accuracy of virtual unenhanced CT images derived from dual-source dual-energy contrast-enhanced CT with that of standard unenhanced CT images for evaluation of sialolithiasis. MATERIALS AND METHODS. All dual-energy CT studies of the neck performed during the preceding 5 years were reviewed for submandibular gland calculi. Only patients who had unenhanced CT and contrast-enhanced CT performed as part of the same evaluation were included in this study. This review yielded 30 patients. Virtual unenhanced CT images were derived from the dual-energy dataset and compared with the true unenhanced CT images by two separate radiologists who assessed the total number of calculi encountered, their location, the largest dimension, and the attenuation of the calculi. The radiation burden incurred for true unenhanced CT and virtual unenhanced CT and the total radiation burden were calculated. RESULTS. Our analysis revealed that measurements of stone size showed good interobserver agreement. The mean stone size was 7.9 ± 5.9 (SD) mm on virtual unenhanced CT and 8.4 ± 5.9 mm on true unenhanced CT (range, 2.0-31.8 mm); the difference was statistically insignificant. The mean stone attenuation differed considerably (p < 0.01) between the virtual and true unenhanced CT images (494.8 ± 187.5 HU and 924.4 ± 374.9 HU, respectively), but correlated well. The mean radiation dose for a dual-phase IV contrast-enhanced CT study was 23.13 mGy (volume CT dose index). The mean dose was 10.93 mGy for the true unenhanced CT phase, thereby suggesting a 47.25% reduction in administered radiation dose when a single-phase contrast-enhanced CT study with virtual unenhanced image reconstructions is performed. CONCLUSION. Virtual unenhanced CT images derived from dual-source dual-energy CT scans of the neck provide accurate assessment of sialolithiasis akin to that provided by conventional CT protocols but at only a fraction of the radiation dosage.

With MR angiography (MRA) of peripheral arterial disease, calcifications are unapparent so a separate calcification-sensitive pulse sequence (proton density-weighted, in-phase three-dimensional stack-of-stars (PDIP-SOS)) is needed for complete assessment. We hypothesized that, despite being acquired separately, MRA and PDIP-SOS images could be co-registered and fused without loss of significant diagnostic information. In a prospective study of 15 patients, MR image fusion enabled the simultaneous display of vessel lumen and vascular calcifications similarly to CT angiography.

Among 109 iohexol-based water-soluble contrast (WSC) challenges performed for suspected small-bowel obstruction, 105 were technically adequate. Among technically adequate studies, colonic contrast (i.e., successful challenge) was seen on 66 abdominal radiographs obtained 8 hours after WSC challenge and 86 abdominal radiographs obtained 24 hours after WSC challenge. Fourteen patients underwent operative management, and 91 underwent nonoperative management (NOM). Successful challenge had a sensitivity of 91.2%, specificity of 78.5%, PPV of 96.5%, NPV of 57.8%, and odds ratio of 38.0 (95% CI, 8.7-165.2) for NOM. Three of 86 patients with successful challenge underwent operative management.

Objective The purpose of this study is to describe the MRI findings and evaluate the prevalence of supraspinatus myotendinous injuries. Materials and methods Among 1001 consecutive shoulders that underwent either conventional MRI or MR arthrography between January and December 2016, 843 shoulders were included. All MR images were retrospectively analyzed for identification and classification into the appropriate grade of acute or chronic rotator cuff myotendinous injuries. Other MRI findings, such as the presence of rotator cuff tendon insertional tears, and clinical information were also evaluated. Results At MRI, 0.47% (4/843) of shoulders had supraspinatus myotendinous injuries involving the anterior muscular bundle exclusively. Chronic grade III (n = 2), acute grade III (n = 1), and acute grade II (n = 1) injuries were identified in three men and one woman (mean age, 44 years) with a clinical history of trauma (n = 2) or of progressive shoulder pain (n = 2). A concurrent supraspinatus insertional tendon tear with either partial (n = 1) or full (n = 1) thickness was present in half the cases. Loss of tension of the myotendinous junction in grade III myotendinous junction injuries led to severe atrophy and fatty infiltration of the anterior supraspinatus. Conclusion Supraspinatus myotendinous junction injuries are uncommon at MRI. These lesions invariably involve the anterior bundle of the supraspinatus muscle and may occur with a concomitant insertional tendon tear. High-grade chronic injuries lead to selective atrophy and fatty infiltration of the anterior supraspinatus muscle.

OBJECTIVE. The purpose of the present study is to evaluate the diagnostic performance of and interreader agreement for CT colonography (CTC) in the local staging of colon cancer, with emphasis given to the FOxTROT (Fluoropyrimidine, Oxaliplatin, and Targeted-Receptor pre-Operative Therapy [Panitumumab]) trial inclusion criteria, which propose a new tailored treatment paradigm for colon cancer that uses neoadjuvant therapy for patients with a high-risk of locoregional disease as determined by imaging. MATERIALS AND METHODS. This biinstitutional retrospective study involved 89 patients (with 93 tumors) who had colon cancer and underwent presurgical CTC. Two radiologists reviewed the CTC studies for local staging, including measurement of the tumor beyond the muscularis propria on a true orthogonal plane. Histopathologic findings for surgical colectomy specimens served as the reference standard for local pathologic staging. The sensitivity, specificity, positive predictive value, and negative predictive value for local determination of the T category, N category, and extramural vascular invasion (EMVI) were calculated separately for each reader. High-risk T category tumors were the same as those as used in the FOxTROT trial. Interreader agreement was assessed using the kappa statistic. RESULTS. Thirty-five of 93 tumors (37.6%) were histologically classified as high-risk tumors (T3c, T3d, or T4 tumors). The interreader agreement was substantial (κ = 0.68) for classifying high-risk tumors with the use of CTC, moderate for differentiating N0 from N1 and N2 (κ = 0.44), and slight for detecting EMVI (κ = 0.15). The diagnostic statistics for CTC for the two readers were as follows: for detection of high-risk tumors, sensitivity was 65.7% and 82.9%, and specificity was 81.0% and 87.9%; for detection of N category–positive disease, sensitivity was 50.9% and 69.8%, and specificity was 50.0% and 72.5%; and for detection of EMVI, sensitivity was 18.2% and 66.7%, and specificity was 60.0% and 91.7%. CONCLUSION. The present study shows that CTC might be a feasible imaging modality for preoperative local staging of higher-risk colon cancers for which neoadjuvant chemotherapy is more suitable on the basis of the FOxTROT trial criteria. However, further studies are required to allow a better generalization of our results.

The purpose of this study was to investigate the diagnostic performance of adaptive 4D volume perfusion CT covering the entire neck for detecting metastatic nodes in patients with head and neck squamous cell carcinoma.Thirty patients with histologically confirmed disease were enrolled. The relation between perfusion parameters and nodal size was analyzed, and perfusion parameters were compared between metastatic and benign nodes. The diagnostic capability for detecting metastatic nodes was evaluated.Significant inverse correlations with nodal size were found for blood flow (r = -0.40, p = 0.002), blood volume (r = -0.32, p = 0.02), and permeability surface product (r = -0.27, p = 0.04) of the metastatic nodes. All three parameters had significantly higher values in association with nodal maximum diameter10 mm compared with diameter ≥ 10 mm (blood flow, p = 0.004; blood volume, p = 0.01; permeability surface product, p = 0.02). Among the nodes with maximum diameter10 mm, blood flow of the metastatic nodes was significantly higher than that of the benign nodes (p = 0.02), whereas among the nodes ≥ 10 mm in diameter, the mean transit time of the metastatic nodes was significantly lower than that of the benign nodes (p = 0.04). In multivariate analysis, blood flow in nodes with maximum diameter10 mm had a significant association with the detection of metastatic nodes. The sensitivity and specificity of blood flow for differentiating metastatic from benign nodes were 73.3% and 70.8%.Findings from 4D volume perfusion CT covering the entire neck may be informative for characterization of cervical nodes. It is worthwhile to include the examination in nodal staging of head and neck squamous cell carcinoma.

The objective of our study was to develop a decision tree model for the early prediction of the severity of acute pancreatitis (AP) using clinical and radiologic scoring systems.For this retrospective study, 192 patients with AP who underwent CT 72 hours or less after symptom onset were divided into two cohorts: a training cohort (n = 115) and a validation cohort (n = 77). Univariate analysis was performed to identify significant parameters for the prediction of severe AP in the training cohort. For early prediction of disease severity, a classification tree analysis (CTA) model was constructed using significant scoring systems shown by univariate analysis. To assess the diagnostic performance of the model, we compared the area under the ROC curve (AUC) with each selected single parameter. We also evaluated the diagnostic performance in the validation cohort.The Acute Physiology and Chronic Health Evaluation (APACHE)-II score, bedside index for severity in acute pancreatitis (BISAP) score, extrapancreatic inflammation on CT (EPIC) score, and Balthazar grade were included in the CTA model. In the training cohort, our CTA model showed a trend of a higher AUC (0.853) than the AUC of each single parameter (APACHE-II score, 0.835; BISAP score, 0.842; EPIC score, 0.739; Balthazar grade, 0.700) (all, p0.0125) while achieving specificity (100%) higher than and accuracy (94.8%) comparable to each single parameter (both, p0.0125). In the validation cohort, the CTA model achieved diagnostic performance similar to the training cohort with an AUC of 0.833.Our CTA model consisted of clinical (i.e., APACHE-II and BISAP scores) and radiologic (i.e., Balthazar grade and EPIC score) scoring systems and may be useful for the early prediction of the severity of AP and identification of high-risk patients who require close surveillance.

The purpose of this study is to provide a more accurate estimation of the radiation dose of contrast-enhanced spectral mammography (CESM) relative to that of 2D digital mammography and tomosynthesis using phantom and patient data and an accepted dosimetry protocol that eliminates vendor-specific average glandular dose (AGD) estimates while including breast density.Patient and phantom AGD estimation was performed using two vendors (system 1 and system 2) in five imaging modes, including 2D, 3D, and CESM imaging. Patient AGD was retrospectively estimated from 45 patients who underwent mammography with all imaging modes during 2012-2016. Patient and phantom AGD were estimated using accepted European and International Atomic Energy Agency protocols for dosimetry and were compared across imaging modes using a paired t test with Bonferroni correction.Phantom data showed that the imaging modes with the lowest to highest AGDs were system 1 2D, followed by system 2 2D and system 2 3D, which had comparable values (p = 0.6), followed by system 1 CESM, and then by system 2 2D plus 3D. One hundred eighty views in 45 patients showed that the system 1 CESM AGD was 1.8 times greater than the system 1 2D AGD (p0.001), 1.2 times greater than the system 2 2D AGD (p0.001), 1.2 times greater than the system 2 3D AGD (p0.001), and 0.6 times less than the system 2 2D plus 3D AGD (p0.001).The CESM dose for system 1 is within an acceptable range as compared with other commonly performed mammographic examinations and should not preclude its use as a diagnostic breast imaging tool.

The hypothesis of this study was that the use of dual-energy spectral techniques in CT can improve accuracy in the diagnosis of acute gangrenous appendicitis.This retrospective study included 209 patients with a pathologic diagnosis of appendicitis. Two board-certified abdominal radiologists reviewed 120-kV simulated images, 40-keV virtual monoenergetic images, and color-coded iodine overlay images. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), accuracy, and interobserver agreement were calculated for each set of images.Forty-four patients (21.0%) had histopathologic results positive for gangrenous appendicitis. The sensitivity of 40-kV virtual monoenergetic imaging was 100% (44/44); specificity, 81.2% (134/165); PPV, 58.7% (44/75); NPV, 100% (134/134); accuracy, 85.2%; and interobserver agreement, 0.99. The corresponding values for the iodine overlay imaging datasets were 100% (44/44), 80.0% (132/165), 57.1% (44/77), 100% (132/132), 84.2%, and 0.99 and for 120-kV simulated imaging were 22.7% (10/44), 96.4% (159/165), 62.5% (10/16), 82.4% (159/193), 77.5%, and 0.93. All cases of gangrenous appendicitis had true-positive results of virtual monoenergetic and iodine overlay imaging. There were no false-negative results of virtual monoenergetic or iodine overlay imaging.In cases of suspected appendicitis, dual-energy CT that includes virtual monoenergetic and iodine overlay imaging is accurate for confirming and excluding the presence of gangrenous appendicitis with high sensitivity and specificity.

We aimed to assess CT andFrom 2010 to 2017, seven patients with surgically proven colloid adenocarcinoma of the lung were identified. CT (both enhanced and unenhanced) and PET/CT findings were analyzed, and the imaging features were compared with histopathologic reports. Clinical and demographic features were also analyzed.In all cases except one, tumors showed low attenuation on unenhanced CT scans, ranging in attenuation from -16.5 to 20.7 HU (median, 9.2 HU). After contrast medium injection, enhancement was scant, so net enhancement ranged from 0.4 to 29.0 HU (median, 4.1 HU). All tumors had a lobulated contour. Stippled calcifications within the tumor were seen in one patient. The maximum standardized uptake value of tumors on PET/CT ranged from 1.5 to 4.5 (median, 3.5). In six of seven patients, FDG accumulation was seen in the tumor walls (n = 3, curvilinear uptake) or in both the tumor walls and tumor septa (n = 3, crisscross uptake). Six patients were alive without recurrence after a median follow-up period of 2.3 years (range, 2 months to 5 years). In one patient, who was alive at follow-up 4 years after imaging and had received adjuvant concurrent chemoradiation therapy after lobectomy, recurrent disease was detected 6 months after completion of the therapy.On CT, pulmonary colloid adenocarcinomas present as lobulated homogeneously low-attenuation tumors. At PET, curvilinear or crisscross FDG uptake is seen within the tumor where tumor cells are lining the walls or septal structures.

The purpose of this study is to evaluate the diagnostic performance of machine learning techniques for malignancy prediction at breast cone-beam CT (CBCT) and to compare them to human readers.Five machine learning techniques, including random forests, back propagation neural networks (BPN), extreme learning machines, support vector machines, and K-nearest neighbors, were used to train diagnostic models on a clinical breast CBCT dataset with internal validation by repeated 10-fold cross-validation. Two independent blinded human readers with profound experience in breast imaging and breast CBCT analyzed the same CBCT dataset. Diagnostic performance was compared using AUC, sensitivity, and specificity.The clinical dataset comprised 35 patients (American College of Radiology density type C and D breasts) with 81 suspicious breast lesions examined with contrast-enhanced breast CBCT. Forty-five lesions were histopathologically proven to be malignant. Among the machine learning techniques, BPNs provided the best diagnostic performance, with AUC of 0.91, sensitivity of 0.85, and specificity of 0.82. The diagnostic performance of the human readers was AUC of 0.84, sensitivity of 0.89, and specificity of 0.72 for reader 1 and AUC of 0.72, sensitivity of 0.71, and specificity of 0.67 for reader 2. AUC was significantly higher for BPN when compared with both reader 1 (p = 0.01) and reader 2 (p0.001).Machine learning techniques provide a high and robust diagnostic performance in the prediction of malignancy in breast lesions identified at CBCT. BPNs showed the best diagnostic performance, surpassing human readers in terms of AUC and specificity.

The primary objective of this study was to compare triple-bolus dual-energy CT (DECT) against standard triple-phase MDCT in terms of appropriateness of patient treatment.One hundred twenty-four patients with suspected renal masses seen at ultrasound were randomized into triple-bolus DECT and triple-phase MDCT groups. Patients in the triple-bolus DECT group underwent synchronous corticomedullary nephrographic delayed-phase triple-bolus DECT. In the triple-phase MDCT group, single-energy triple-phase scans were acquired after an unenhanced scan. The primary outcome was appropriateness of treatment received at 1 year. The predefined noninferiority limit was 10%. Histopathologic analysis or follow-up confirmed the benign or malignant nature of the masses. Diagnostic accuracy to differentiate benign from malignant masses was calculated. Size-specific dose estimates were compared.After excluding six patients, 118 patients were analyzed (62 triple-bolus DECT; 56 triple-phase MDCT). Treatment appropriateness was not significantly different (p = 0.9397) between the two groups (61/62 [98.39%; 95% CI, 95.26-101.52%] for triple-bolus DECT vs 55/56 [98.21%; 95% CI, 94.74-101.68%] for triple-phase MDCT). The absolute difference was 0.18% (95% CI, -4.48% to 4.84%). Both techniques had similar diagnostic accuracy (sensitivity, 98.25% vs 96.67%; specificity, 98.17% vs 97.97%). The mean (± SD) size-specific dose estimate was significantly lower for triple-bolus DECT than for triple-phase MDCT (19.02 ± 4.07 vs 57.04 ± 15.17 mGy; p0.0001).Single-acquisition triple-bolus DECT is noninferior to triple-phase MDCT, with similar diagnostic accuracy but delivering significantly less radiation.

The objective of our study was to evaluate the diagnostic performance of CT in the identification of anastomotic leaks.This was a study of patients who underwent bowel surgery and a subsequent postoperative CT examination performed specifically for investigating for an anastomotic leak. The study group included patients with surgically confirmed anastomotic leaks (n = 59), and the control group included patients without anastomotic leaks (n = 48) confirmed by either repeat surgery or uneventful clinical follow-up for at least 6 months. Two radiologists and two radiology residents independently reviewed each CT examination for specific CT findings from a set of predetermined imaging predictors. The sensitivity and specificity for each imaging predictor were calculated for each reader, and the interobserver agreement was calculated using the Cohen kappa coefficient. Diagnostic performance was assessed using ROC curve analysis.The most sensitive imaging predictor was intraabdominal free fluid (95.3%). Leakage of intraluminal contrast agent was also a highly specific imaging predictor (96.6%). Substantial interobserver agreement was shown for intraabdominal free gas (κ = 0.76) and leakage of intraluminal contrast agent (κ = 0.76). Overall diagnostic performance in correctly identifying surgically confirmed leaks, as assessed by the area under the ROC curve, ranged from 0.76 to 0.86. Diagnostic performance was higher for all readers when intraluminal contrast agent was used and reached the anastomosis, with the exception of one reader, whose diagnostic performance remained unchanged.Diagnostic performance of CT was highest when an intraluminal contrast agent was used. Meticulous and careful use of an intraluminal contrast agent is therefore important in this patient population.

The purpose of this article is to evaluate the image quality and added value of split-bolus contrast agent injection combining late arterial and portal venous phases compared with single-bolus contrast agent injection late arterial phase CT enterography.Consecutive patients who underwent CT enterography before and after implementation of a single-bolus CT enterography protocol were included. Attenuation and contrast-to-noise ratio (CNR) were assessed by ROI measurements of the bowel wall and arterial and venous structures. Subjective enhancement of the bowel wall (1, arterial; 2, mucosal; 3, transmural; 4, transmural with mucosal hyperenhancement) and bowel abnormalities were assessed by two independent readers. MR enterography examinations, endoscopy reports, and surgery reports within 30 days after CT enterography were used to produce a composite outcome.Sixty-six patients were included in our study: 33 (mean [± SD] age, 46.0 ± 19.8 years) who underwent split-bolus CT enterography and 33 (mean age, 49.9 ± 19.0 years) who underwent single-bolus CT enterography. Bowel wall attenuation and CNR were higher for split-bolus CT enterography than for single-bolus CT enterography at 120 kVp (enhancement, 98.7 ± 23.1 HU vs 85.1 ± 23.3 HU; CNR, 6.4 ± 2.5 vs 4.4 ± 2.3; p0.01). Subjective ratings of bowel wall enhancement were higher with the split-bolus CT enterography than the single-bolus CT enterography (2.6 ± 0.8 vs 2.3 ± 0.6; p0.001). Split-bolus CT enterography led to a higher detection rate of mucosal hyperenhancement than did single-bolus CT enterography in patients with active inflammatory bowel disease (100.0% [7/7; 95% CI, 59.0-100.0%] vs 33.3% [2/6; 95% CI, 4.3-77.7%]; p = 0.02), whereas both protocols had a specificity of 100.0% (9/9).Split-bolus CT enterography led to improved CNR (47%) compared with single-bolus CT enterography and significantly increased the detection rate of mucosal hyperenhancement in patients with active inflammatory bowel disease.

The purpose of this study was to analyze the quality of MDCT images obtained using iopromide with two different concentrations of iodine (300 and 370 mg I/mL) in daily clinical settings.Patients from 38 hospitals in China undergoing abdominal or pelvic CT with iopromide were prospectively recruited. MDCT was performed using iopromide with an iodine concentration of 300 or 370 mg I/mL. CT quality image was graded as excellent, good, adequate, and poor. Objective indicators were the contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR). Outcomes were compared according to organ studied, tumor type (benign vs malignant), saline usage, and type of MDCT (16-MDCT vs 64-MDCT).A total of 4506 patients (63.7% men) with a mean (± SD) age of 56.3 ± 14.1 years and mean body mass index (weight in kilograms divided by the square of height in meters) of 23.2 ± 3.3 were included. Iopromide with 300 mg I/mL was used for 3042 patients (67.5%), and 370 mg I/mL was used for 1464 patients (32.2%). A total of 1847 scans (41.0%) had excellent image quality, 2454 (54.5%) had good quality, 176 (3.9%) had adequate quality, and 29 (0.6%) had poor quality. No differences were noted between CT scans that did or did not use saline, 16-MDCT versus 64-MDCT scans, and 300 versus 370 mg I/mL iopromide. Variations in the CNR and SNR were noted between the two iodine concentrations with respect to other parameters examined.Iopromide with both concentrations of iodine provided acceptable image quality, though according to CNR and SNR, one or the other may provide better quality in different situations.

The purpose of this study is to identify the anatomic locations of appendixes on CT when graded compression sonography fails to visualize the appendix.The study included 197 patients with suspected appendicitis whose appendixes were not visualized on graded compression sonography performed with typically used transducers of at least 10 MHz, who underwent CT within 48 hours following graded compression sonography, and who had available either pathologic examination following surgery or 6-week follow-up if surgery was not performed. Appendixes were retrospectively localized using four transverse quadrants (including the posteromedial quadrant) centered on the ileocecal valve and projected vertically, the craniocaudal level relative to the iliac crests, and the depth of the appendix as measured from the surface of the skin. Data were assessed using the Fisher exact test, t test, multinomial test, binomial distribution, ANOVA, and linear regression.Appendixes were most frequently located in the posteromedial quadrant (123 of 197 patients [62.4%]; 95% CI, 55.3-69.2%) at a statistically significantly greater frequency than that expected by chance (p0.00001). Appendixes were located above the iliac crests in 19.8% of patients (39/197; 95% CI, 14.5-26.1%) and at depths exceeding the penetration of typical transducers of at least 10 MHz in 19.3% of patients (38/197; 95% CI, 14.0-25.5%). All appendixes (95% CI, 98.1-100.0%) were located within the range of 6-MHz transducers.Appendixes that are not visualized on graded compression sonography are most frequently located in the posteromedial quadrant and are often located above the iliac crests or at depths too great for visualization with typically used transducers of at least 10 MHz. Accordingly, when the appendix is not visualized on graded compression sonography, targeted scanning of the posteromedial quadrant and the region above the iliac crests, and scanning with 6-MHz transducers, may enable visualization of the appendix and are recommended additions to scanning protocols.

Colorectal liver metastases (CLM) have a variable response to radioembolization. This may be due at least partly to differences in tumor arterial perfusion. The present study examines whether quantitative measurements of enhancement on preprocedure triphasic CT can be used to predict the response of CLM to radioembolization.We retrospectively reviewed patients with CLM treated with radioembolization who underwent pretreatment PET/CT and triphasic CT examinations and posttreatment PET/CT examinations. A total of 31 consecutive patients with 60 target tumors were included in the present study. For each tumor, we calculated the hepatic artery coefficient (HAC), portal vein coefficient (PVC), and arterial enhancement fraction (AEF) based on enhancement measurements on pretreatment triphasic CT. HAC and PVC are estimates of the hepatic artery and portal vein blood supply. AEF, which is the arterial phase enhancement divided by the portal phase enhancement, provides an estimate of the hepatic artery blood supply as a fraction of the total blood supply. For each tumor, the metabolic response to radioembolization was based on findings from the initial follow-up PET/CT scan obtained at 4-8 weeks after treatment.A total of 55% of CLM had a complete or partial metabolic response. Arterial phase enhancement, the HAC, and the PVC did not predict which tumors responded to radioembolization. However, the AEF was statistically significantly greater in tumors with a complete or partial metabolic response than in tumors with no metabolic response (i.e., those with stable disease or disease progression) (p = 0.038). An AEF of less than 0.4 was associated with a 40% response rate, whereas an AEF greater than 0.75 was associated with a 78% response rate.Response to radioembolization can be predicted using the AEF calculated from the preprocedure triphasic CT.

Lower gastrointestinal hemorrhage is a common cause of hospitalization and has substantial associated morbidity and financial cost. CT angiography (CTA) is emerging as an alternative to (99m)Tc-labeled RBC scintigraphy (RBC scintigraphy) for the localization of acute lower gastrointestinal bleeding (LGIB); however, data on comparative efficacy are scant. The aim of this study was to assess the utility of CTA compared with RBC scintigraphy in the overall evaluation and management of acute LGIB.We retrospectively reviewed images from all CTA examinations performed for suspected acute LGIB at our tertiary care hospital from January 2010 through November 2011. The comparison group was determined by retrospective review of twice the number of RBC scintigraphic scans consecutively obtained from June 2008 to November 2011 for the same indication. All CTA and RBC scintigraphic scans were reviewed for accurate localization of the site and source of suspected active LGIB.In total, 45 CTA and 90 RBC scintigraphic examinations were performed during the study period. Seventeen (38%) CTA scans showed active gastrointestinal bleeding compared with 34 (38%) RBC scintigraphic scans (p = 1.000). However, the site of bleeding was accurately localized on 24 (53%) CTA scans. This proportion was significantly greater than the proportion localized on RBC scintigraphic scans (27 [30%]) (p = 0.008). There were no significant differences between the two groups in average hospital length of stay, blood transfusion requirement, incidence of acute kidney injury, or in-hospital mortality.Both CTA and RBC scintigraphy can be used to identify active bleeding in 38% of cases. However, the site of bleeding is localized with CTA in a significantly higher proportion of studies.

The objective of our study was to assess the incidence of contrast-induced nephropathy (CIN), dialysis, and graft loss after direct intraarterial infusion of iodine-based contrast medium (CM) in renal allograft recipients.One hundred patients underwent renal graft catheter arteriography between 2006 and 2014. CIN was defined as an increase in serum creatinine value of 0.5 mg/dL or more above the creatinine value before arteriography. CIN could be assessed in 37 patients with creatinine levels obtained before arteriography and 24-72 hours after arteriography. Dialysis requirement and renal allograft loss at 30 days after the procedure were recorded in all 100 patients.In the 37 patients who could be assessed for CIN, three patients (8%) met the criteria for CIN. In a subgroup analysis, there was an increased incidence of CIN in patients undergoing angiography alone (25%) compared with those in the angioplasty and stenting group (0%) (p = 0.028). At 30 days after the procedure, none (0/100) of the patients required dialysis or had graft failure.In a cohort of patients with a single renal allograft undergoing renal graft catheter arteriography using iodine-based CM, the overall incidence of CIN was low and no major adverse outcomes were noted at 30 days after the procedure. However, in a subgroup analysis, the patients who underwent arteriography alone-that is, without angioplasty or stenting-had a statistically significant higher rate of CIN.

The purpose of this study was to assess the effects of traction during MR arthrography of the wrist on joint space widening, cartilage visibility, and detection of tears of the triangular fibrocartilage complex (TFCC) and intrinsic ligaments.A prospective study included 40 wrists in 39 patients (25 men, 14 women; mean age, 35 years). MR arthrography was performed with a 3-T MRI system with and without axial traction. Two radiologists independently measured wrist and carpal joint space widths and semiquantitatively graded articular cartilage visibility. Using conventional arthrography as the reference standard and working in consensus, they assessed for the presence of tears of the TFCC, lunotriquetral ligament (LTL), and scapholunate ligament (SLL). Visibility of a tear before traction was compared with visibility after traction.With traction, all joint spaces in the wrist and carpus were significantly widened (change, 0.15-1.01 mm; all p0.006). Subjective cartilage visibility of all joint spaces improved after traction (all p ≤ 0.048) except for that of the radioscaphoid space, which was well visualized even before traction. Conventional arthrography depicted 24 TFCC tears, seven LTL tears, and three SLL tears. The accuracy of tear detection improved after traction for the TFCC (98% after traction vs 83% before traction), the LTL (100% vs 88%), and the SLL (100% vs 95%). Tear visibility improved after traction for 54% of TFCC tears, 71% of LTL tears, and 66% of SLL tears.Wrist MR arthrography with axial traction significantly improved the visibility of articular cartilage and the detection and visibility of tears of the TFCC and intrinsic ligaments. The results favor more widespread use of traction during MR arthrography of the wrist.

The purpose of this study was to compare a cerebral CT venography (CTV) technique performed on a 320-MDCT scanner with the use of a time-density curve (TDC) and a small volume of IV contrast medium (35 mL, with 15 mL used for the test bolus) with CTV performed using an established reference technique in which scanning is performed at a fixed time delay of 30 seconds with the use of a larger volume of contrast medium (100 mL).The time of peak enhancement was determined from the TDC generated from a scan in which a test bolus dose was used. CTV was performed at the time of peak enhancement. The diagnostic quality of 31 CTV venograms acquired using this technique was compared retrospectively with the diagnostic quality of 29 CTV venograms obtained at a fixed time delay of 30 seconds. The densities in the major venous sinuses and the degree of arterial contamination on the scans acquired using the two techniques were compared using objective and semiobjective methods. The semiobjective assessments were made independently by two neuroradiologists.Attenuation was higher in the venous structures seen on CTV images acquired using the TDC technique. Of the scans obtained using the TDC technique, the proportion deemed to be of good quality, on the basis of a grading scale, was statistically significantly higher (p0.05). Also, the degree of arterial contamination was statistically significantly lower (p0.05). The interrater agreement for semiobjective assessments ranged from good to very good.We describe a CTV technique performed using a low volume of IV contrast medium and a TDC on a 320-MDCT scanner. This technique provides better venous opacification and lower arterial contamination compared with use of the fixed time-delay technique.

OBJECTIVE. The purpose of this study was to systematically investigate radiation dose reduction using automated tube voltage selection during CT angiography (CTA) and to evaluate the impact of contrast medium (CM) injection protocols on dose reduction. MATERIALS AND METHODS. A circulation phantom containing the thoracic and abdominal vasculature was used. Four different concentrations of CM (iopromide 300 and 370 mg I/mL and iomeprol 350 and 400 mg I/mL) were administered while maintaining an identical iodine delivery rate (1.8 g I/s) and total iodine load (20.0 g). Three different scanning protocols for CTA of the thoracoabdominal aorta were used: protocol A, no dose modulation; protocol B, automated tube current modulation (CARE Dose4D); and protocol C, automated tube voltage selection (CARE kV). The dose-length product was recorded to calculate the effective dose. Attenuation values (in Hounsfield units), image noise levels, and signal-to-noise ratios (SNRs) in six predefined intravascular sites (three thoracic and three abdominal) were measured by two readers. All values were analyzed using the Kruskal-Wallis test and two-way ANOVA. RESULTS. There was a significant reduction in the effective dose (in millisieverts) for protocols B (mean +/- SD, 2.03 +/- 0.1 mSv) and C (1.00 +/- 0.0 mSv) compared with protocol A (4.34 +/- 0.0 mSv). The dose was reduced by 53% for protocol B and by 77% for protocol C. No significant differences were found in the effective dose among the different CM injection protocols within the scanning protocols; all p values were > 0.05. The attenuation values and SNRs were comparable among all the different CM injection protocols; all p values were > 0.05. CONCLUSION. A large radiation dose reduction (77%) can be achieved using automated tube voltage selection independent of the CM injection protocol.

The purpose of this study was to define the cholangiographic patterns of ischemic cholangiopathy and clinically silent nonanastomotic biliary strictures in donation-after-cardiac-death (DCD) liver grafts in a large single-institution series. We also examined the correlation of the radiologic findings with laboratory data and clinical outcomes.Data were collected for all DCD liver transplants at one institution from December 1998 to December 2011. Posttransplant cholangiograms were obtained during postoperative weeks 1 and 3 and when clinically indicated. Intrahepatic biliary strictures were classified by anatomic distribution and chronologic development. Radiologic findings were correlated with laboratory data and with 1-, 3-, and 5-year graft and patient survival rates.A total of 231 patients received DCD grafts. Cholangiograms were available for 184 of these patients. Postoperative cholangiographic findings were correlated with clinical data and divided into the following three groups: A, normal cholangiographic findings with normal laboratory values; B, radiologic abnormalities and cholangiopathy according to laboratory values; and C, radiologic abnormalities without laboratory abnormalities. Group B had four distinct abnormal cholangiographic patterns that were predictive of graft survival. Group C had mild nonprogressive multifocal stenoses and decreased graft and patient survival rates, although cholangiopathy was not detected in these patients according to laboratory data.Patterns and severity of nonanastomotic biliary abnormalities in DCD liver transplants can be defined radiologically and correlate with clinical outcomes. Postoperative cholangiography can depict the mild biliary abnormalities that occur in a subclinical manner yet cause a marked decrease in graft and patient survival rates in DCD liver transplants.

The objective of this study was to determine the accuracy of renal measurement on CT in multiple imaging planes.In this study, three board-certified radiologists retrospectively measured 110 kidneys on CT in 55 consecutive patients. Five measurement methods were used: axial, coronal single image, coronal multiimage, sagittal single image, and sagittal multiimage. The coronal database was sent to a postprocessing workstation, and each radiologist performed a maximum renal measurement using a best off-axis plane that was our reference standard. An ANOVA test with repeated measures and posthoc Bonferroni corrected t tests were performed.The mean differences (± standard error) compared with the reference standard method were as follows: axial, 7.7 ± 0.7 mm; coronal single image, 13.1 ± 1.4 mm; coronal multiimage, 6.4 ± 0.8 mm; sagittal single image, 6.4 ± 0.6 mm; and sagittal multiimage, 2.8 ± 0.3 mm. The reference standard measurement was larger (p0.001), whereas the coronal single-image measurement (p ≤ 0.006) was smaller than all other methods. The sagittal multiimage (p ≤ 0.005) was statistically significantly different from all other methods. There were no statistically significant differences among the axial, coronal multiimage, and sagittal single-image methods (p ≥ 0.088).The single-image coronal method is the least accurate, with an error of approximately 13 mm. The axial, multiimage coronal, and single-image sagittal methods underestimate renal size by approximately 6-8 mm. Multiimage sagittal is the most accurate method for measuring kidneys with an error of approximately 3 mm.

The purpose of this study was to determine whether MRI could more confidently characterize indeterminate small renal lesions (15 mm) previously seen on CT scans of potential renal donor patients and whether such characterization could impact surgical management and donor candidate status.After dedicated contrast-enhanced renal CT examinations of a population of renal donor patients identified indeterminate small renal lesions (15 mm), dedicated renal MRI examinations were performed for 55 of those patients. Two radiologists used consensus reading of established MRI characteristics to characterize indeterminate small lesions as simple cysts, hemorrhagic cysts, angiomyolipomas, or solid renal masses.A total of 94 indeterminate small renal lesions were detected on CT. MRI was able to confidently diagnose 93 of those lesions, including 83 cysts, eight hemorrhagic cysts, and two angiomyolipomas. MRI directly affected the surgical management of four of the patients (7%).For potential renal donor patients, MRI can be an effective means of characterizing lesions that are deemed to be too small to characterize by CT. MRI can also potentially alter the surgical management and donor status of this group of patients.

Diagnosis and staging of duodenal gastrointestinal stromal tumors (GISTs) by noninvasive imaging is critical for effective treatment, but the imaging features of duodenal GISTs remain largely undefined because of their rarity. The purpose of this article was to characterize duodenal GISTs using CT.Thirty-four patients with duodenal GISTs were analyzed by clinical symptom evaluation, pathologic examination, and CT in this retrospective study. Unenhanced and contrast-enhanced examinations were performed in all patients. Imaging characteristics, including the lesion location, size, growth pattern, ulceration, internal components, arterial blood supply, intratumoral arterioportal shunting, intratumoral vessels, rim enhancement, and enhancement patterns were reviewed.The duodenal GISTs were solitary masses with well-defined margins. The average diameter was 7.1 cm. The second portion was the most common site (20/34). Ulceration was a common feature (15/34). Calcification was uncommon (3/34), and mixed growth pattern was more common (26/34). Rim enhancement (24/34) and mixed enhancement pattern (15/34) were common. Arterial blood supply, intratumoral vasculature, and draining veins were all detected and were obvious on the arterial phase. The portal venous trunk and superior mesenteric vein were the main veins into which early arterioportal shunting drained.Primary duodenal GISTs are generally large, well-defined, heterogeneously enhancing, and hypervascular masses with a prominent mixed growth pattern on CT images. Our findings suggest that CT can help depict the origin of the tumoral arteries and draining veins on the arterial phase and may be a key defining diagnostic feature for duodenal GISTs.

OBJECTIVE. The purpose of this study was to evaluate the prevalence, MDCT angiography (MDCTA) appearance, associated congenital cardiovascular abnormalities, and prognosis of anomalous origin of one pulmonary artery from the aorta (AOPA) on the basis of MDCTA. MATERIALS AND METHODS. We conducted a retrospective search of patients with AOPA from our database in a single center, consisting of 5729 patients referred for MDCTA with known or suspected congenital heart diseases from transthoracic echocardiography. The clinical information, subtypes of AOPA, associated cardiovascular anomalies, and surgical and clinical outcomes were retrospectively collected and analyzed. The MDCTA images were retrospectively processed for analysis, and the MDCTA and echocardiography images were interpreted by radiologist and cardiologist without knowledge of the actual diagnosis or surgical outcome. RESULTS. AOPA was seen in 19 patients (14 males and five females; median age, 3 months; range, 4 days–21 years) showing a prevalence of 0.33%. Anomalous origin of the right pulmonary artery (AORPA, 89%), proximal origin subtype of the AOPA (89%), and ipsilateral aortic wall origin of AOPA (58%) were more commonly seen. In addition to the benefit of preoperative planning, MDCTA also supplemented echocardiography by providing accurate diagnosis of AOPA and other associated cardiovascular anomalies compared with transthoracic echocardiography (TTE). We found a total of four patients (21%) with misdiagnosis by TTE, including three patients with underdiagnosis of AOPA and one patient with misdiagnosis as transposition of the great arteries. In addition, two other patients had AOPA diagnosed, but the associated patent ductus arteriosus (PDA) was not detected. MDCTA revealed 95% association with other congenital cardiovascular anomalies, including PDA (71% of AORPA), and aortic arch anomalies (100% of anomalous origin of the left pulmonary artery, AOLPA). The types of surgery depended on the MDCTA findings, including the sub type, origin sites of AOPA, and associated cardiovascular anomalies. Analysis of the pulmonary arterial sizes showed the McGoon ratios in these patients with a median value of 2.4 (range, 1.5–2.9). Surgical treatment performed before the age of 1 year enabled normalization of pulmonary artery pressure in 92% of patients. CONCLUSION. AOPA had a prevalence of 0.33% among patients with congenital heart disease in our series. MDCTA was an important supplement for the diagnosis, delineating the different subtypes and origin sites of AOPA and permitting preoperative planning of AOPA in patients suspected on the basis of echocardiography of having AOPA because accurate diagnosis and early surgical treatment remain the mainstays in improving patient outcome.

OBJECTIVE. The purpose of this article is to compare two 3D dynamic contrast-enhanced (DCE) MRI measurement techniques for MR renography, a radial k-space weighted image contrast (KWIC) sequence and a cartesian FLASH sequence, in terms of intrasubject differences in estimates of renal functional parameters and image quality characteristics. SUBJECTS AND METHODS. Ten healthy volunteers underwent repeated breath-hold KWIC and FLASH sequence examinations with temporal resolutions of 2.5 and 2.8 seconds, respectively. A two-compartment model was used to estimate MRI-derived perfusion parameters and glomerular filtration rate (GFR). The latter was compared with the iohexol GFR and the estimated GFR. Image quality was assessed using a visual grading characteristic analysis of relevant image quality criteria and signal-to-noise ratio calculations. RESULTS. Perfusion estimates from FLASH were closer to literature reference values than were the KWIC sequences. In relation to the iohexol GFR (mean [± SD], 103 ± 11 mL/min/1.73 m(2)), KWIC produced significant underestimations and larger bias in GFR values (mean, 70 ± 30 mL/min/1.73 m(2); bias = -33.2 mL/min/1.73 m(2)) compared with the FLASH GFR (110 ± 29 mL/min/1.73 m(2); bias = 6.4 mL/min/1.73 m(2)). KWIC was statistically significantly (p < 0.005) more impaired by artifacts than was FLASH (AUC = 0.18). The average signal-enhancement ratio (delta ratio) in the cortex was significantly lower for KWIC (delta ratio = 0.99) than for FLASH (delta ratio = 1.40). Other visually graded image quality characteristics and signal-to-noise ratio measurements were not statistically significantly different. CONCLUSION. Using the same postprocessing scheme and pharmacokinetic model, FLASH produced more accurate perfusion and filtration parameters than did KWIC compared with clinical reference methods. Our data suggest an apparent relationship between image quality characteristics and the degree of stability in the numeric model-based renal function estimates.

The purpose of this study was to investigate and validate adaptation of a cardiovascular CT angiography contrast injection protocol for lower tube potential.Eighty-three patients evaluated for thoracic aortic disease with a 256-MDCT scanner were imaged at 120 kV (group 1) or 100 kV (group 2) with the same contrast protocol (90 mL iopromide 370 mg I/mL at 3.5 mL/s). A pharmacokinetic model was validated and used to simulate aortic attenuation in group 2 patients with 20%, 33%, and 44% reduction in contrast volume. A 44% volume reduction was applied to 50 additional patients who underwent imaging at 100 kV (group 3). Patient characteristics, scanning and radiation parameters, and objective and subjective image indexes were compared among groups.Group 2 patients had higher mean aortic blood attenuation (399±61 HU) than group 1 patients (281±48 HU) (p0.001) but similar image noise. Group 3 and group 1 patients had similar mean aortic attenuation and noise. Subjective assessment of image quality indicated that group 3 and group 1 had comparable percentages of images with good or excellent diagnostic confidence scores (reader 1, 98% vs 96%; reader 2, 96% vs 96%).Lower tube potential (100 kV) for cardiothoracic CT could be accompanied by a 44% reduction in contrast volume with satisfactory aortic blood-pool attenuation in most patients. More personalized adaptation of the contrast protocol that takes into account patient characteristics and tube potential is necessary to ensure sufficient contrast enhancement for all patients.

The purpose of this study was to evaluate the usefulness of quantification of lung perfused blood volume (PBV) with dual-energy CT (DECT) for assessment of the severity of acute pulmonary thromboembolism (PTE).We retrospectively analyzed the records of 72 patients with PTE and 168 without PTE who underwent DECT. The PTE patients were divided into high-, intermediate-, and low-risk groups based on clinical symptoms and right ventricular dysfunction. Correlations between quantification of whole-lung PBV and clinical severity were evaluated. Also evaluated was the relation between quantification of whole-lung PBV and right-to-left ventricular diameter ratio on CT images, which was used as an indicator of right ventricular dysfunction.In the PTE and control groups, the whole-lung PBVs were 27.6 ± 7.9 and 29.9 ± 6.8 HU with a significant difference between them (p0.0281). In the high-, intermediate-, and low-risk PTE groups, the whole-lung PBVs were 16.0 ± 2.9, 21.0 ± 4.2, and 31.4 ± 5.8 HU with a significant difference between them (p0.05). There was no significant difference in whole-lung PBV between the control group and the low-risk PTE group, but there was a significant difference between the control group and the other two PTE groups. In PTE patients, whole-lung PBV had negative correlation with right-to-left ventricular diameter ratio (R = -0.567, p0.001).Quantification of lung PBV with DECT is useful for assessment of the clinical severity of PTE and can be used as an indicator of right ventricular dysfunction.

The objective of our study was to catalog the anatomic features shown on preoperative CT that precluded living-donor liver donation.We retrospectively reviewed the records of 159 consecutive candidates who were evaluated for potential right or left lobe liver donation from November 2007 to January 2012 using MDCT angiography and cholangiography. For the potential donors who were excluded secondary to findings depicted on preoperative imaging, we determined which findings precluded donation.In two (1%) patients who had no prohibitive preoperative imaging findings, anatomic abnormalities were detected intraoperatively that precluded transplantation. Sixty-one (38%) candidates were excluded from liver donation on the basis of imaging findings. Of these patients, 40 (66%) had inadequate liver volume, 14 (23%) had vascular or biliary variants, five (8%) had steatosis, and two (3%) were found to have renal cell carcinoma. Arterial and biliary variants were the most common reason for exclusion based on anatomic findings.Inadequate liver volume was the most common reason for exclusion based on preoperative imaging. Arterial and biliary anatomic variants precluded both right and left lobe transplantation in a number of cases.

The objective of our study was to evaluate the value that PET/CT adds to adrenal protocol CT for characterizing adrenal metastasis in oncologic patients.Sixty-eight oncologic patients with 68 adrenal masses underwent both adrenal protocol CT and (18)F-FDG PET/CT. For adrenal protocol CT, metastasis was diagnosed if a mass measured more than 10 HU on unenhanced CT and if the absolute and relative percentage washouts were less than 60% and 40%, respectively. For PET/CT, metastasis was diagnosed if FDG uptake of the lesion was equal to or greater than that of the liver. Diagnostic accuracies were compared between these two imaging modalities.The accuracy of adrenal protocol CT and PET/CT for a metastatic lesion, defined as a lesion with FDG uptake equal to or higher than that of the liver, was 85.3% (58/68) and 76.5% (52/68), respectively. However, the accuracy of PET/CT increased to 89.7% (61/68) when a lesion with high FDG uptake alone was considered a metastatic lesion. When both adrenal protocol CT and PET/CT were positive for metastasis, the accuracy increased to 91.2% (62/68), but the sensitivity decreased to 70.6% (12/17).Adding PET/CT to adrenal protocol CT improves the accuracy for adrenal metastasis in oncologic patients when a lesion with high FDG uptake alone is considered metastasis.

The purpose of this study was to prospectively evaluate the contrast enhancement, vascular depiction, image quality, and radiation dose of low-tube-voltage whole-body CT angiography (CTA) performed with low-concentration iodinated contrast material.Whole-body CTA was performed on 109 patients with a 64-MDCT scanner. Patients were randomized into three groups: CTA with 240-mg/mL contrast material at 80 kVp (240-80 group), 300-mg/mL at 80 kVp (300-80 group), and 370-mg/mL at 120 kVp (370-120 group). Signal-to-noise ratio (SNR), arterial depiction, image quality, and radiation dose were assessed. Figure of merit was computed to normalize signal-to-noise ratio, estimated effective dose, and iodine weight.In the 240-80 group, the mean load of administered iodine was 21.6 g; for the 300-80 group, 26.8 g; and the 370-120 group, 34.0 g (p0.05). The ranges of mean vascular enhancement were 508-521 HU, 546-593 HU, and 435-442 HU (p0.05). Arterial depiction and image quality were comparable for the 240-80 and 370-120 groups and were greater for the 300-80 group than the other two groups in selected arteries (p0.05). Effective dose was higher (p0.05) in the 370-120 group (2.8-5.4 mSv) than in the others (2.3-4.3 mSv). The figure of merit in the 240-80 group was greater than (p0.05) or comparable to that in the 370-120 group.Use of 240-mg/mL contrast material at 80 kVp seems appropriate for routine whole-body CTA and beneficial for reduction of iodine load and radiation dose, whereas use of 300-mg/mL contrast material may marginally improve delineation of selected small arteries.

The purpose of this study was to identify the CT features required for differentiating mucin-producing cystic neoplasms of the liver (mucinous cystic neoplasms and cyst-forming intraductal papillary neoplasms of the bile duct) from solitary bile duct cysts.CT images of pathologically confirmed mucinous cystic neoplasms (n = 15), cyst-forming intraductal papillary neoplasms of the bile duct (n = 16), and solitary bile duct cysts (n = 31) were reviewed. Analysis of the CT findings included shape, presence of septa, location of septa (peripheral vs central), thickness of septa (thin vs thick), mosaic pattern, mural nodules, intracystic debris, calcification, upstream bile duct dilatation, downstream bile duct dilatation, and communication between a cystic lesion and the bile duct. The maximum size of a cystic lesion and the maximum size of the largest mural nodule were measured.The presence of septa, central septa, mural nodules, upstream bile duct dilatation, and downstream bile duct dilatation were found to be significant CT findings for differentiating mucinous cystic neoplasms and cyst-forming intraductal papillary neoplasms of the bile duct from solitary bile duct cysts (p0.05 for each finding). When two of these five criteria were used in combination, the sensitivity and specificity for diagnosing mucin-producing cystic neoplasms and cyst-forming intraductal papillary neoplasms of the bile duct were 87% (27 of 31) and 87% (27 of 31), respectively. When two of these five criteria were used in combination, the sensitivity and specificity for diagnosing mucinous cystic neoplasms and cyst-forming intraductal papillary neoplasms of the bile duct were 87% (27 of 31) and 87% (27 of 31), respectively [corrected].With the use of specific CT criteria, mucin-producing cystic neoplasms of the liver can be differentiated from solitary bile duct cysts with a high degree of accuracy.

ObjectiveThe purpose of this study was to determine whether contrast-enhanced CT quantification of the hepatic fractional extracellular space (ECS) correlates with the severity of diffuse liver disease.Materials and methodsThe cases of 70 patients without (46 men, 24 women; mean age, 59.1 years) and 36 patients with (23 men, 13 women; mean age, 63.1 years) cirrhosis who had undergone unenhanced and 10-minute delayed phase contrast-enhanced CT were retrospectively identified. By consensus one experienced radiologist and one trainee measured the CT attenuation of the liver and aorta to estimate the fractional ECS, defined as the ratio of the difference between the attenuation of the liver on 10-minute and unenhanced images to the difference between the attenuation of the aorta on 10-minute and unenhanced images multiplied by 1 minus the hematocrit. Findings were correlated with each patient's Model of End-Stage Liver Disease (MELD) score.ResultsThe mean MELD score was higher in patients with than in those without cirrhosis (14.3 ± 7.3 versus 7.20 ± 2.4, p < 0.0001). The mean fractional ECS was significantly greater in patients with cirrhosis than in those without cirrhosis (41.0% ± 9.0% versus 23.8% ± 6.3%, p < 0.0001). The fractional ECS correlated with the MELD score (r = 0.572, p < 0.0001) and was predictive of cirrhosis with an area under the receiver operating characteristic curve of 0.953 (p < 0.0001). The sensitivity and specificity of an expanded fractional ECS greater than 30% for the prediction of cirrhosis were 92% and 83%. Multivariate linear regression revealed that the fractional ECS is complementary to the MELD score as a predictor of cirrhosis (p < 0.0001).ConclusionNoninvasive contrast-enhanced CT quantification of the fractional ECS correlates with the MELD score, an indicator of the severity of liver disease, and merits further study.

The purpose of this study was to validate the usefulness of MDCT for diagnosis of a sharp or pointed esophageal foreign body according to esophageal level.Forty-two patients with a history of sharp or pointed foreign body ingestion were reviewed retrospectively. Two observers interpreted the CT and the conventional radiography datasets separately. If a foreign body was directly identified, it was regarded as a positive finding. Even if no high-density foreign body was found, detection of a secondary finding was considered to be a positive finding. Diagnostic performance of MDCT and conventional radiography were compared according to esophageal level. Final diagnosis was made by esophagoscopy or surgery in addition to the clinicoradiologic result.MDCT was statistically superior to conventional radiography for diagnosis of a thoracic esophageal foreign body for both observers (p0.001 for each). No significant difference in sensitivity between CT and conventional radiography for diagnosis of cervical esophageal foreign body was noted regardless of observer. Both observers could identify all complicated conditions with MDCT regardless of esophageal level. However, in two of three cases of complicated thoracic esophageal foreign bodies, neither observer could detect foreign bodies on conventional radiography; furthermore, the observers could not identify pneumomediastinum.In cases of sharp or pointed foreign body ingestion, if the result of an initial inspection of oro- and hypopharynx reveals negative findings, the first imaging modality should be MDCT for better diagnosis and management.

We retrospectively reviewed the CT findings of lower respiratory tract infection (LRTI) due to parainfluenza virus (PIV) to determine the imaging features of PIV infection and to identify any differences compared with the CT appearances of LRTIs due to respiratory syncytial virus (RSV), adenovirus, and influenza virus.The imaging features of LRTI from PIV over a 51-month period were retrospectively reviewed. The specific CT findings and overall pattern of infection in patients with LRTI due to PIV were recorded and were then compared with the CT appearances of RSV, adenovirus, and influenza LRTIs using data from a previous study.Twenty-four chest CT examinations of 24 patients with PIV infection were analyzed. Tree-in-bud opacities were the most common finding (13/24, 54%), and the airway-centric pattern of disease--characterized by combinations of bronchial wall thickening, tree-in-bud opacities, and peribronchiolar consolidation (bronchitis, bronchiolitis, and bronchopneumonia)--was the most common pattern (16/24, 67%). In comparison with previous data on RSV, adenovirus, and influenza virus, PIV showed tree-in-bud opacities and airway-centric patterns significantly more often than adenovirus or influenza virus. PIV and RSV showed similar CT findings and patterns of disease.Despite varying CT appearances of PIV LRTI, it most often shows airway-centric disease and is similar to the appearance of RSV infection, both of which are members of the Paramyxoviridae family of viruses.

The purpose of this study was to compare image quality and lesion detectability in the evaluation of hypervascular hepatocellular carcinoma (HCC) on low-tube-voltage half-dose liver CT scans subjected to sinogram-affirmed iterative reconstruction (SAFIRE) with the quality and detectability on full-dose scans reconstructed with filtered back projection (FBP).A total of 126 patients with suspected HCC who underwent liver CT including arterial phase scanning at 80 kVp in the dual-source mode (300 mAs for each tube) were included in the study. The half-dose arterial scans were reconstructed with FBP, iterative reconstruction in image space (IRIS), and five SAFIRE strengths (S1-S5) and were compared with full-dose virtual scans (600 mA) reconstructed with FBP. We assessed image noise, contrast-to-noise ratio (CNR) of the liver and blood vessels, and lesionto-liver CNR. Two radiologists evaluated image quality and lesion detectability attained with the different imaging sets.Image noise on SAFIRE images was significantly lower than that on the other images, and the CNRs on SAFIRE images were higher than those on half-dose FBP images (p0.001). In addition, lesion-to-liver CNR on the half-dose S5 SAFIRE images was higher than on IRIS and full-dose FBP images (p0.05). Among the half-dose scans, SAFIRE images had significantly better image quality than FBP images (p0.05). Regarding lesion detection, half-dose SAFIRE images were better than half-dose FBP images and were comparable with full-dose FBP images (observer 1, 91.8% vs 96%; observer 2, 98% vs 98%; p0.05).Performing half-dose 80-kVp liver CT with SAFIRE technique may increase image quality and afford comparable lesion detectability of hypervascular HCC at a reduced radiation dose compared with full-dose CT with FBP.

The purpose of this article is to quantify the CT radiation dose increment in five organs resulting from the administration of iodinated contrast medium.Forty consecutive patients who underwent both un-enhanced and contrast-enhanced thoracoabdominal CT were included in our retrospective study. The dose increase between CT before and after contrast agent administration was evaluated in the portal phase for the thyroid, liver, spleen, pancreas, and kidneys by applying a previously validated method.An increase in radiation dose was noted in all organs studied. Average dose increments were 19% for liver, 71% for kidneys, 33% for spleen and pancreas, and 41% for thyroid. Kidneys exhibited the maximum dose increment, whereas the pancreas showed the widest variance because of the differences in fibro-fatty involution. Finally, thyroids with high attenuation values on unenhanced CT showed a lower Hounsfield unit increase and, thus, a smaller increment in the dose.Our study showed an increase in radiation dose in several parenchymatous tissues on contrast-enhanced CT. Our method allowed us to evaluate the dose increase from the change in attenuation measured in Hounsfield units. Because diagnostic protocols require multiple acquisitions after the contrast agent administration, such a dose increase should be considered when optimizing these protocols.

Differentiation of grade 3 astrocytoma from glioblastoma multiforme can be difficult with conventional structural imaging but is important for prognosis. The purpose of this study was to assess perfusion CT in differentiating high-grade gliomas (HGGs) and their role in prognosis in the care of patients with HGG.Twenty patients with previously untreated HGG underwent prospective evaluation with perfusion CT. Permeability surface area product (PS) and cerebral blood volume (CBV) were calculated by the deconvolution method and were compared between HGGs with Student two-sample t tests. Receiver operating characteristic curves were generated for PS, CBV, and the conjoint factor PS + CBV. Cox regression analysis was used to correlate these parameters with patient survival over a follow-up period. Hazard ratios were calculated, and Kaplan-Meier survival curves were drawn.There was a significant difference between grade 3 and grade 4 gliomas for PS (p = 0.022) and PS + CBV (p = 0.019) but not for CBV alone (p = 0.411). Receiver operating characteristic analyses showed that PS (area under the curve [AUC], 0.72) and CBV + PS (AUC, 0.73) can be used to differentiate grade 3 from grade 4 gliomas but that CBV alone cannot be so used (AUC, 0.54). There was a significant relation between patient outcome and age (p = 0.034) and CBV + PS (p = 0.048). Patients with HGG and a CBV + PS greater than 9 had a poor outcome (hazard ratio, 6.00).PS and CBV + PS can be used to differentiate grade 3 from grade 4 gliomas. The outcome of patients with HGG depends on age and CBV + PS.

The purpose of this study was to use measured glomerular filtration rate (GFR), the reference standard of renal function, to assess the deleterious effect of iodinated contrast media on renal function. Such an effect has been traditionally defined as a greater than 0.5-mg/dL increase in serum creatinine concentration or a 25% or greater increase 24-72 hours after the injection of iodinated contrast medium.This pilot investigation was focused on the consequences of clinically indicated IV injection of iodinated contrast media; intraarterial injection was excluded. One hundred thirteen patients with normal serum creatinine concentrations were enrolled in an approved protocol. At random, as chosen by one of the investigators, patients underwent imaging with one of three monomeric agents (iopamidol 300, iopromide 300, iohexol 300) and one dimeric agent (iodixanol 320). Measured GFR was determined immediately before CT and approximately 3 and 72 hours after the contrast injection for the CT examination. Iodinated contrast medium, a glomerular filtrate with no tubular excretion or reabsorption, was the GFR marker. Measured GFR was determined by x-ray fluorescence analysis with nonisotopic iodinated contrast media.Monomeric and dimeric contrast agents in diagnostic CT volumes (based on bodyweight and imaging protocol) did not induce a significant change in measured GFR (95% confidence by Wilcoxon test), suggesting that use of the evaluated contrast media will not lead to more than a 12% variation.The three monomeric agents studied and the one dimeric agent were equivalent in terms of lack of a significant effect on measured GFR when administered to patients with a normal GFR.

The objective of this study was to prospectively evaluate whether intraarticular anesthesia can reduce pain after MR or CT arthrography of the shoulder.This study included 120 patients who underwent CT or MR arthrography of the shoulder. The patients were randomized into two groups: the study group (n = 60), each administered an intraarticular injection of the contrast agent mixed with a local anesthetic (2% mepivacaine); and the control group (n = 60), each injected with the contrast agent only. Each patient's pain level was assessed at five phases-baseline and immediately, 2 hours, 1 day, and 2 days after injection-by using a visual analog scale or a verbal rating scale. The net pain score at each phase was also calculated. The pain course and net pain score were compared between study and control groups by repeated-measures analysis of variance. After the patients were divided into subgroups according to patient- or procedure-related factors, the efficacy of the intraarticular local anesthetic in each subgroup was evaluated.The pain course showed a quadratic trend and was not significantly different between study and control groups. The net pain score also was not significantly different between the two groups. No subgroup showed a significantly different efficacy of the intraarticular local anesthetic between the two groups.Intraarticular local anesthesia did not reduce arthrography-related pain.

We sought to use cardiac CT angiography (CTA) to longitudinally examine the relationship between changes in aortic stiffness and of the atherosclerotic burden over time.One hundred sixty-four patients with suspected coronary artery disease underwent two retrospectively ECG-gated cardiac CTA studies an average of 12 ± 10 months apart. Arterial stiffness was represented by the aortic distensibility index (ADI) and atherosclerosis by segment involvement score (SIS) (defined as the number of coronary artery segments per patient displaying atherosclerotic plaque). Changes in ADI and SIS between the studies were compared using linear and logistic regression accounting for differences in clinical and demographic baseline characteristics.Age (p = 0.004), time between studies (p = 0.02), and increase in SIS (p0.001) were associated with a decrease in ADI on univariate analysis. Increase in SIS remained a significant independent predictor of decreased ADI on both multivariate logistic regression (with change in ADI represented categorically) and multivariate linear regression (both p0.001).On longitudinal evaluation with cardiac CTA, the progression of aortic stiffness is associated with the progression of coronary atherosclerosis. Although outcome studies are needed, a comprehensive assessment of vascular health with cardiac CTA, including both indexes of arterial stiffness and atherosclerotic burden, may improve risk stratification and therapy monitoring.

OBJECTIVE. The purpose of this study is to describe the MDCT findings of anomalous pulmonary venous drainage (APVD) in a pediatric population using a 256-MDCT dual-source scanner with a high-pitch protocol. CONCLUSION. MDCT is a fast and noninvasive technique that allows detailed and comprehensive visualization of APVD characteristics in a pediatric population. High-pitch acquisitions with scanners using a high volume of coverage permit low radiation doses and are an accurate modality for assessing these patients.

Washout on delayed phase (or equilibrium phase) imaging of an arterially hyperenhancing lesion is an excellent predictor of hepatocellular carcinoma (HCC). The purpose of our study was to quantitatively define washout in pathologically proven HCC. A quantitative definition of HCC may minimize interobserver variability and facilitate more accurate diagnosis.We identified 47 liver lesions that were hyperenhancing in the arterial phase from 24 patients who underwent triphasic MDCT as part of preoperative evaluation for liver transplantation. All HCCs were pathologically proven. Regions of interest were obtained of lesions and areas of adjacent liver on arterial, portal venous, and delayed phase images. Enhancement profiles were assessed by three radiologists.Of the 47 hypervascular lesions, 14 HCCs were identified. There was a statistically significant difference in percentage attenuation ratio (defined as 100 × ratio of attenuation of adjacent liver to that of the lesion) between lesions that were HCC (median percentage attenuation ratio, 121) and those that were not (median percentage attenuation ratio, 101) on delayed phase. Percentage attenuation ratio ≥ 107 on delayed phase imaging achieved maximal sensitivity (100%) with good specificity (75.8%), positive predictive value (PPV) (63.6%), and negative predictive value (NPV) (100%) in HCC detection. Percentage attenuation ratio also correlated well with radiologists' assessments of enhancement profiles of lesions (multinomial logistic regression McFadden R(2), 0.72; chi-square p,0.01).Our analysis of simple CT attenuation measurements indicates that percentage attenuation ratio offers excellent sensitivity, specificity, PPV, and NPV for HCC detection and very good correlation with radiologists' assessments of washout.

The aim of our study was to correlate perfusion MDCT parameters and immunohistochemical markers of angiogenesis in prostate cancer.Twenty-two patients scheduled for radical surgical prostatectomy because of biopsy-proven prostate cancer underwent perfusion CT on a 64-MDCT scanner. Eight contiguous 5-mm sections were acquired at 1-second intervals for 45 seconds followed by three additional scans every 10 seconds after the administration of 80 mL of iodinated contrast medium (350 mg I/mL). Blood volume, blood flow, mean transit time, and permeability surface-area product were calculated, dividing each slice into nine square regions. Values obtained were correlated with the mean microvessel density (MVD) and mean vascular area of corresponding areas on histologic macrosections.The mean values of the perfusion parameters detected on all square fields of patients with prostate cancer, benign hyperplasia, chronic prostatitis, and healthy tissue were, respectively, 18.36 ± 6.30, 19.49 ± 8.46, 19.67 ± 11.44, and 20.32 ± 4.53 mL/min/100 g for blood flow; 8.45 ± 2.75, 6.21 ± 4.32, 4.94 ± 2.31, and 5.44 ± 2.67 mL/100 mg for blood volume; 19.19 ± 4.45, 18.74 ± 4.91, 16.24 ± 4.12, and 16.37 ± 4.83 seconds for mean transit time; and 26.34 ± 11.88, 18.67 ± 9.15, 18.08 ± 7.72, and 19.93 ± 7.22 mL/min/100 g for permeability surface-area product. Both blood volume and the permeability surface-area product of cancerous squares showed the highest correlation with mean MVD and mean vascular area (0.618 [p0.01] and 0.614 [p0.01], respectively) and the highest area under the curve (0.769 and 0.708).Our results show that blood volume and permeability surface-area product measurements obtained with perfusion CT have the highest correlation with immunohistochemical markers of angiogenesis in prostate cancer.

The purpose of this study is to determine a concentration of iodinated contrast media in saline and 5% dextrose in water (D5W) for organ hydrodissection, a technique used to physically separate and protect tissues adjacent to thermal ablations.A total of 28 samples were prepared from 1:1000-1:1 iohexol or iothalamate meglumine contrast media in either normal saline or D5W. Samples alone or juxtaposed with a homogeneous liver-mimicking phantom were imaged by CT using 80-120 kVp and 10-300 mAs. Mean CT numbers and noise were measured from the fluid, background air, phantom adjacent to the fluid, and phantom distant from the fluid. Visibility was determined from the contrast-to-noise ratio between the fluid and phantom, whereas streaking artifact was quantified by relative noise in the phantom. Measures were individually fit using multiple linear regression to determine an optimal contrast-to-fluid ratio for increased visualization without streaking. Contrast media- and blood-doped saline and D5W were also tested to determine whether such doping altered their electrical conductivity.Iohexol concentration most influenced CT number; volumetric ratios of 1:1000-1:1 produced 20 HU to over 3000 HU. CT numbers were weakly dependent on x-ray tube voltage, whereas contrast-to-noise ratio and streaking artifacts were somewhat dependent on tube output. An optimal ratio of iohexol in fluid was determined to be 1:50. There was no significant difference between the electrical impedances of doped and pure saline or D5W (p0.5, all cases).A 1:50 ratio of iohexol in saline or D5W provides an optimal combination of increased visibility on CT without streaking artifacts.