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Diffusion-weighted magnetic resonance (MR) imaging is increasingly used in the detection and characterization of pancreatic lesions. Diffusion-weighted imaging may provide additional information to radiologists evaluating patients who have cystic or solid neoplasms of the pancreas. Because of greater freedom of motion of water molecules in fluid-rich environments, simple cysts in the pancreas have higher signal intensity on diffusion-weighted images with a b value of 0 sec/mm2 and lower signal intensity on high-b-value images. High apparent diffusion coefficient (ADC) values can be obtained on ADC maps because of the T2 “shine-through” effect. In contrast, solid neoplasms of the pancreas show increased signal intensity relative to the pancreas on diffusion-weighted images with a b value of 0 sec/mm2 and relatively high signal intensity on high-b-value images. Diffusion-weighted imaging can help detect solid pancreatic neoplasms with extremely dense cellularity or extracellular fibrosis by demonstrating significantly low ADC values, and these neoplasms may be better detected on diffusion-weighted MR images because of better contrast, although the resolution is generally worse. However, diffusion-weighted imaging may not be capable of helping definitively characterize solid lesions as inflammatory or neoplastic because of an overlap in ADC values between the two types. For example, it is difficult to distinguish poorly differentiated pancreatic adenocarcinoma from mass-forming pancreatitis at diffusion-weighted imaging because of similarly low ADC values attributed to dense fibrosis.

Multidetector computed tomography (MDCT) enables imaging of the entire arterial tree non-invasively. Optimal technical considerations for performing MDCT angiography (MDCTA) are essential for accurate diagnosis and atherosclerotic disease stratification. This review article focuses on the various technical aspects necessary for peripheral computed tomographic angiography (CTA) acquisition. Common clinical indications for peripheral MDCTA and the latest scan protocols are described. The essential issue of radiation dose reduction is discussed, along with methods of optimal contrast bolus detection and delivery. Post-processing techniques are also presented. Previously, digital subtraction angiography was the only established reliable imaging technique to quantify atherosclerotic disease load; however, MDCTA may now challenge this old gold standard, along with other non-invasive techniques such as magnetic resonance angiography (MRA).

Background: To evaluate feasibility and reproducibility of quantification of perinephric hematoma volume on multidetector-row CT (MDCT)., Methods: Perinephric hematomas in 63 patients (42 males, 21 females, median age: 49 years) imaged with contrast-enhanced MDCT of the abdomen were evaluated. A semi-automated segmentation software was applied to quantify hematoma volume. Reproducibility for quantification of hematoma volume was evaluated by repeated measurements in 20 patients. Statistical analyses were performed by using Student's t test. Interobserver and intraobserver variability was evaluated by Bland-Altman plots. P < 0.05 denoted statistical significance, Results: Quantification of hematoma volume was feasible in all cases. One step, direct quantification of volume was possible in 21 patients (33.33%) with small hematomas that did not reach upper and lower renal poles (range: 3.12-183.98 mL; mean: 39.92 mL). Quantification of hematoma size was performed indirectly in 42 patients (66.67%) with larger hematomas that extended beyond the renal poles by subtracting the ipsilateral renal volume from the combined kidney and hematoma volumes (range: 27.08-2431.3 mL; mean: 435.31 mL). Mean quantification time was 45 and 71 s for small and large hematomas, respectively (P < 0.05). Mean intraobserver and interobserver variability for determination of hematoma volume was 0.14% (95% CI, -1.57% to 1.85%) and 2.04% (95% CI, -1.77% to 5.85%), respectively. There was no significant difference in renal volume between ipsilateral and contralateral kidneys (P > 0.05)., Conclusion: Quantification of perinephric hematoma was feasible from MDCT data in all patients and was reproducible.

Background & Aims: Chemoembolization is one of several standards of care treatment for hepatocellular carcinoma (HCC). Radioembolization with Yttrium-90 microspheres is a novel, transarterial approach to radiation therapy. We performed a comparative effectiveness analysis of these therapies in patients with HCC., Methods: We collected data from 463 patients who were treated with transarterial locoregional therapies (chemoembolization or radioembolization) over a 9-year period. We excluded patients who were not appropriate for comparison and analyzed data from 245 (122 who received chemoembolization and 123 who received radioembolization). Patients were followed for signs of toxicity; all underwent imaging analysis at baseline and follow-up time points. Overall survival was the primary outcome measure. Secondary outcomes included safety, response rate, and time-to-progression. Uni- and multivariate analyses were performed., Results: Abdominal pain and increased transaminase activity were more frequent following chemoembolization (P < .05). There was a trend that patients treated with radioembolization had a higher response rate than with chemoembolization (49% vs 36%, respectively, P = .104). Although time-to-progression was longer following radioembolization than chemoembolization (13.3 months vs 8.4 months, respectively, P = .046), median survival times were not statistically different (20.5 months vs 17.4 months, respectively, P = .232). Among patients with intermediate-stage disease, survival was similar between groups that received chemoembolization (17.5 months) and radioembolization (17.2 months, P = .42)., Conclusions: Patients with HCC treated by chemoembolization or radioembolization with Yttrium-90 microspheres had similar survival times. Radioembolization resulted in longer time-to-progression and less toxicity than chemoembolization. Post hoc analyses of sample size indicated that a randomized study with > 1000 patients would be required to establish equivalence of survival times between patients treated with these two therapies., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Objective: The purposes of this study were to construct a model for estimation of splenic volume from standardized one-dimensional diameters of the spleen and to compare that model with the ellipsoid model for estimation of splenic volume., Materials and Methods: In this retrospective study, segmentation software was used for semiautomated quantification of splenic volume by counting CT voxels in 193 consecutively registered patients. For standardization of one-dimensional measurements, the software was used to measure transaxial diameter in the slice with the largest splenic cross-sectional area. By incorporation of splenic volume and the product of width, thickness, and length into the linear regression equation, a model for estimation of splenic volume was constructed, and its performance was externally assessed. Splenic volume also was calculated with the formula for a prolate ellipsoid. The ellipsoid volume and best-fit volumes were compared with segmented splenic volume by use of Bland-Altman plot and Lin concordance correlation. A value of p < 0.05 denoted statistical significance., Results: Splenic width was the best one-dimensional predictor of splenic volume (r = 0.84, p < 0.05). The linear regression fitted model for estimation of splenic volume (V(R)) in the initial 100 patients was V(R) = (0.36 × W × T × L) + 28, where W is width, T is thickness, and L is length (R(2) = 0.91, p < 0.05) and was externally validated by estimation of splenic volume in the other 93 patients. Compared with that observed with use of the ellipsoid formula, mean bias decreased from 22.57% to 0.93%, and the Lin coefficient increased from 0.81 to 0.96 with application of the best-fit model for calculation of splenic volume., Conclusion: The best-fit model V(R) = (0.36 × W × T × L) + 28 is more optimized than the ellipsoid formula and is associated with less bias for estimation of splenic volume.

We compared the effect of low-density barium sulfate neutral oral contrast agent on the diameter of normal appendix and its luminal content versus that of water on multidetector-row CT. CT scans of 24 patients who had been imaged on two separate occasions for the evaluation of pancreatic pathology, once with water and subsequently with low-density barium sulfate as the neutral oral contrast agent were evaluated (total of 48 scans). Studies were randomized and reviewed in consensus on a workstation in the stack mode by two radiologists blinded to the type of oral contrast. The appendix was measured at baseline and 10 days later to obtain an average diameter. Results of the water and low-density barium sulfate groups were compared using paired t test. Contents of the appendiceal lumen were also noted (gas, fluid, mixed, and collapsed appendix). The average diameter of the appendix for scans obtained with water and low-density barium sulfate was 4.09 ± 0.87 mm (median, 4.22 mm; range, 2.50-5.65 mm) and 4.13 ± 0.93 mm (median, 4 mm, range, 2.2-5.65 mm), respectively. This difference was not statistically significant (P = 0.69). There was no statistically significant difference in the appendiceal content when water or low-density barium sulfate were used as oral contrast (χ (2) = 4.25, P = 0.89). Low-density barium sulfate does not affect appendiceal content or diameter and, therefore, should not adversely affect evaluation of the appendix on multidetector row CT.

Purpose: To evaluate the utility of diffusion-weighted magnetic resonance imaging (DWI) in pancreatic ductal adenocarcinoma with various grades of differentiation., Materials and Methods: Following Institutional Review Board (IRB) approval, 21 consecutive patients with surgical pathology-proven pancreatic adenocarcinomas were retrospectively evaluated. Histopathologic characteristics and grades of differentiation of adenocarcinomas were analyzed. Twenty-one patients without a known history of pancreatic disease were evaluated as the control group. Anatomic MR images and DW images were acquired using 1.5-T MR systems. DWI with b values of 0 and 500 sec/mm² were performed on both patients and control groups. The difference in mean apparent diffusion coefficient (ADC) values among groups of normal pancreatic parenchyma, adenocarcinomas with poor differentiation, and adenocarcinomas with well/moderate differentiation were compared using one-way analysis of variance., Results: Mean ADCs of pancreatic adenocarcinomas (1.77 ± 0.45 × 10⁻³ mm²/sec) was not significantly lower than that of normal parenchyma (1.98 ± 0.31) (P = 0.09). When adenocarcinomas were subdivided based on grades of differentiation, however, poorly differentiated adenocarcinoma with histopathologic characteristics of limited glandular formation and dense fibrosis had significantly lower ADCs (1.46 ± 0.17) compared to those of well/moderately differentiated adenocarcinomas (2.10 ± 0.42) characterized by neoplastic tubular structures (P < 0.01). Well/moderately differentiated adenocarcinomas with dense fibrosis showed significantly lower ADC values (1.49 ± 0.19) than those with loose fibrosis (2.26 ± 0.30) (P = 0.01)., Conclusion: Difference in ADC values using DWI between poorly and well/moderately differentiated pancreatic ductal adenocarcinoma may relate to differences in glandular formation and density of fibrosis., (Copyright © 2010 Wiley-Liss, Inc.)

Rationale and Objectives: Comprehensive training in cardiac imaging during radiology residency is imperative if radiologists are to maintain a significant role in this rapidly growing field. In this study, radiology chief residents were surveyed to assess the current status of cardiac imaging training in radiology residency programs. The responses to this survey may be helpful in understanding current trends in cardiac imaging training and how such training can be improved in the future., Materials and Methods: Chief residents at accredited radiology residency programs were sent an e-mail with a link to a 17-question Web-based survey. The survey assessed the organization of cardiac imaging training in each residency program, imaging modalities incorporated into cardiac imaging training, the role of residents on cardiac imaging rotations, and attitudes of residents about their cardiac imaging training and the future of cardiac imaging., Results: Responses were obtained from 52 of 112 (46%) programs. Seventy-one percent had at least one dedicated cardiac imaging rotation during their residencies. Fifty-two percent and 62% of respondents reported <5 hours of cardiac imaging-related case conferences and didactic lectures per year, respectively. Most had cardiac computed tomography or magnetic resonance imaging incorporated into their cardiac imaging training. Although 92% felt that cardiac imaging training is important, only 17% felt that they currently received adequate training in cardiac imaging., Conclusions: The majority of residency programs represented in this survey had at least one dedicated cardiac imaging rotation for their residents. Most of these programs had few cardiac imaging-related conferences and lectures per year. Although most chief residents believed that cardiac imaging training is important, only a minority felt that they currently received adequate training in cardiac imaging., (Copyright (c) 2010 AUR. Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the correlation between change in attenuation and tumor metabolic activity assessed by using fluorodeoxyglucose (FDG) positron emission tomography (PET) in colon cancer liver metastases treated with yttrium 90 ((90)Y) radioembolization., Materials and Methods: This Health Insurance Portability and Accountability Act-compliant retrospective study was approved by the institutional review board; patient informed consent was waived. Unresectable chemorefractory colon cancer liver metastases treated with (90)Y radioembolization in 28 patients were evaluated at pre- and posttreatment multidetector computed tomographic (CT) and FDG PET scans. Maximum cross-sectional diameter, volume, and overall attenuation of target lesions were calculated. The percentage change (%Delta) in these parameters after treatment was calculated and correlated with the standardized uptake value (SUV) analysis at FDG PET. The accuracy of the radiologic parameters in helping predict response to treatment at FDG PET was assessed. Data were analyzed by using the Student t, Wilcoxon matched pair, Mann-Whitney, Spearman rank correlation, and chi(2) tests. The significance level was set at .05., Results: Seventy-four metastatic lesions in 10 women and 18 men (mean age, 61.5 years +/- 14.3 [standard deviation]) were evaluated. Mean follow-up interval for multidetector CT after treatment was 30 days. A significant reduction in maximum cross-sectional diameter, volume, and attenuation was observed from pre- to posttreatment multidetector CT (P < .05). The %Delta in attenuation had higher correlation with %Delta in SUV (r = 0.61) than diameter (r = 0.39) or volume (r = 0.49) and also predicted the metabolic activity at FDG PET with higher sensitivity (P < .001). By using a threshold level of a reduction in attenuation of 15% or greater, attenuation showed 84.2% sensitivity and 83.3% specificity in predicting response at FDG PET evaluation., Conclusion: Changes in attenuation of colon cancer liver metastases treated with (90)Y radioembolization correlate highly with metabolic activity at FDG PET and may be useful as an early surrogate marker for assessing treatment response., (RSNA, 2010)

Context: Response Evaluation Criteria in Solid Tumors (RECIST) (unidimensional), World Health Organization (WHO) (bidimensional), and European Association for Study of the Liver (EASL) (necrosis) guidelines are commonly used to assess response following therapy for hepatocellular carcinoma (HCC). No universally accepted standard exists., Objectives: To evaluate intermethod agreement between these 3 imaging guidelines and to introduce the concept of the "primary index lesion" as a biomarker for response., Design, Setting, and Participants: Single-center comprehensive imaging analysis including 245 consecutive patients with HCC who were treated with chemoembolization or radioembolization between January 2000 and December 2008. Computed tomography and magnetic resonance imaging scans (N = 1065) were reviewed to assess response in the "primary index lesion," defined as the largest tumor targeted during first treatment., Main Outcome Measures: Intermethod agreement (kappa statistics) between RECIST, WHO, and EASL guidelines response; correlation of WHO and EASL response in the primary index lesion with time to progression and survival., Results: Kappa coefficients were 0.86 (95% confidence interval [CI], 0.80-0.92) between the WHO and RECIST guidelines, 0.24 (95% CI, 0.16-0.33) between RECIST and EASL, and 0.28 (95% CI, 0.19-0.36) between WHO and EASL. Disease progressed in 96 patients; 113 died. The hazard ratio for time to progression in responders compared with nonresponders was 0.36 (95% CI, 0.23-0.57) for WHO, 0.38 (95% CI, 0.24-0.58) for RECIST, and 0.38 (95% CI, 0.22-0.64) for EASL. Hazard ratios for survival in responders compared with nonresponders in univariate and multivariate analyses were 0.46 (95% CI, 0.32-0.67) and 0.55 (95% CI, 0.35-0.84) for WHO and 0.36 (95% CI, 0.22-0.57) and 0.54 (95% CI, 0.34-0.85) for EASL. Hazard ratios for survival in responders vs nonresponders in patients with solitary and multifocal HCC were 0.39 (95% CI, 0.19-0.77) and 0.51 (95% CI, 0.32-0.82) for WHO and 0.26 (95% CI, 0.10-0.67) and 0.47 (95% CI, 0.28-0.79) for EASL., Conclusions: Among a group of patients with HCC, agreement for classification of therapeutic response was high between the RECIST and WHO guidelines but low between each of these and EASL. Application of these methods to measure response in a primary index lesion resulted in statistically significant correlations with disease progression and survival.

Rationale and Objectives: The aim of this study was to analyze the morphology of pancreatic cystic masses detected on multi-detector row computed tomography (MDCT) to determine whether single-dimension measurements of these masses are accurate reflections of their volumes., Materials and Methods: Twenty-five pancreatic cystic masses detected on MDCT in 25 patients were evaluated. Pancreatic cysts were segmented on MDCT using commercially available software. All measurements were obtained twice by two independent investigators, and the means of values for segmented cyst volume (Vs) (milliliters), maximum transaxial diameter (millimeters), and elongation value (defined as 1 - [width/length], where 1 = ellipsoid and 0 = spherical) were reported for each cystic lesion. The volume of each cyst was also calculated (Vc) using the maximum transaxial diameter, with the hypothesis that the cyst was spherical. Student's t test was used to analyze the differences between values of Vs and Vc. Bland-Altman plots and Lin's concordance correlation were used to assess agreement between different measurement techniques. A P value < .05 denoted statistical significance. Interobserver variability was also determined using the Bland-Altman method., Results: There was a significant difference between Vs and Vc (P < .0001). The elongation values ranged from 0.28 to 0.83 (mean, 0.57 +/- 0.12; median, 0.56). Mean interobserver variability was 1.7% (95% confidence interval, -4.89% to 8.30%)., Conclusions: The results suggest that pancreatic cystic masses are not spherical. Therefore, a cyst's single largest transaxial dimension is not an accurate surrogate of its actual volume.

Objective: The purpose of our study was to evaluate the utility of apparent diffusion coefficient (ADC) values for characterizing adrenal lesions and determine if diffusion-weighted imaging (DWI) can distinguish lipid-rich from lipid-poor adenomas., Materials and Methods: We retrospectively evaluated 160 adrenal lesions in 156 patients (96 women and 60 men; mean age, 63 years). ADCs and signal intensity (SI) decrease on chemical shift imaging were measured in adrenal lesions with a wide variety of pathologies. Lipid-rich and lipid-poor adenomas were identified by unenhanced CT. The overall predictive power of ADC, SI decrease, and lesion size were determined by receiver operating characteristic (ROC) analysis. Areas under the ROC curve (AUC) were compared for equivalence using nonparametric methods. Sensitivity, specificity, and positive and negative predictive values were calculated. Correlation coefficients were used to assess ADCs versus percentage SI decrease and ADCs versus CT attenuation., Results: ADCs of adrenal malignancies (median, 1.67 x 10(-3) mm(2)/s; interquartile range, 1.41-1.84 x 10(-3) mm(2)/s) were not different compared with those of benign lesions (1.61 x 10(-3) mm(2)/s; 1.27-1.96 x 10(-3) mm(2)/s; p > 0.05). Cysts (2.93 x 10(-3) mm(2)/s; 2.70-3.09 x 10(-3) mm(2)/s) showed higher ADCs than the remaining adrenal lesions (p < 0.05). The median ADCs of lipid-rich adenomas did not differ from those of lipid-poor ones (p > 0.05). The CT attenuation had no negative or positive correlation with the ADCs of adrenal adenomas (r = -0.05, p = 0.97)., Conclusion: Unlike lesion size and percentage decrease in SI, the ADCs were not useful in distinguishing benign from malignant adrenal lesions. Lipid-poor adenomas could not be distinguished from lipid-rich adenomas and all other nonfatty lesions of the adrenal gland with DWI.

Objectives: Response Evaluation Criteria in Solid Tumors (RECIST) guidelines assume spherical shape of tumors. Morphology of pancreatic adenocarcinoma (PAC) on multidetector row computed tomography was investigated to evaluate the applicability of RECIST guidelines., Methods: Study population comprised 16 patients with histologically confirmed localized PAC enrolled in a phase II clinical trial of chemoradiation. Pancreatic adenocarcinomas were segmented on baseline and follow-up multidetector row computed tomography with commercially available software. Tumor volumes (mL), RECIST diameter (mm), volume equivalent sphere diameter (VESD, mm), maximum 3-dimensional diameter (M3DD, mm), and elongation value were obtained. RECIST diameter, VESD and M3DD of the tumors at baseline and follow-up were compared to determine differences. Elongation values were analyzed. The significance level was set at P less than 0.05., Results: Mean volume, RECIST diameter, VESD, M3DD, and elongation for baseline versus follow-up studies were 23.12 mL versus 19.43 mL (P > 0.05), 41.86 mm versus 39.35 mm (P > 0.05), 33.14 mm versus 32.1 mm (P > 0.05), 51.76 mm versus 51.73 mm (P > 0.05), and 0.67 versus 0.76 (P > 0.05), respectively. There was a significant difference at baseline and follow-up between RECIST diameter, VESD, and M3DD (P < 0.05, in all instances)., Conclusions: Our results suggest that PACs are not spherical in shape. Evaluation of PAC treatment response based on RECIST guidelines may not be accurate.

Enteric duplication cysts are rare congenital anomalies that may occur anywhere along the gastrointestinal tract, most commonly involving the small bowel. The distal ileum, jejunum, and duodenum are affected in descending order of frequency. We describe a case of biliary dilatation and duodenal intussusception caused by an enteric duplication cyst in an adult patient. To our knowledge, there are no other reported cases of this entity in an adult in the English literature. Multidetector computed tomography (MDCT) findings are emphasized, and the value of multiplanar reformation (MPR) in forming a correct preoperative differential diagnosis is discussed.

Rational and Objectives: We evaluated the ability of 64-slice computed tomography (CT), conventional cine-angiography, and intravascular ultrasound (IVUS) to detect stent fractures under ideal conditions. Coronary stent fracture has been implicated as one of the mechanisms of stent thrombosis and, perhaps, in-stent restenosis. However, the preferred imaging modality in detecting fractures in coronary stents has not been well established., Materials and Methods: Four different types of commonly used coronary stents (Cypher, Taxus, Vision, Hepacoat) each with three strut fractures (Cypher, 5; Taxus, 5; Vision, 4; Hepacoat, 5) were nominally deployed in polyurethane tubes and imaged with 64-slice CT, conventional cine-angiography, and IVUS. For each stent type, an unfractured control stent was also imaged., Results: Overall accuracy (84.1% vs. 73.9%), sensitivity (80.7 vs. 77.2%), and specificity (100% vs. 58.3%) for stent fracture detection was higher with 64 multislice CT compared to conventional cine-angiography. Stent fractures were not accurately detected by IVUS. Fracture detection by multislice CT was best when the stents were imaged at 45 degrees to the z-axis., Conclusions: Under ideal in vitro conditions, CT has a high accuracy when used to evaluate coronary stent fractures. The overall accuracy, sensitivity, and specificity of detecting stent fractures are lower by conventional cine-angiography. Stent fractures were not detected using IVUS.

The terms wandering liver, hepatic torsion, and hepatic vagrancy have been applied to cases in which hepatic hypermobility results in displacement of the liver from its normal position within the right upper quadrant of the abdomen. This is thought to result from multiple factors, including the lack of normal hepatic suspensory ligaments, persistence of the ventral mesentery, and lack of inferior vena cava tethering Siddins and Cade (Aust N Z J Surg 60:400-403, 1990). A wandering liver has been described in both adults Siddins and Cade (Aust N Z J Surg 60:400-403, 1990), Tate (Am Surg 59:455-458, 1993), Chiavarini and Chang (Radiology 115:47-48, 1974), Cope and Levy (South Afr Med J 40:366-369, 1966), Sharov (Vestn Roentgenol Radiol 35:63-64, 1960), Puthenpurayil et al. (AJR 177:1113-1115, 2001), Fuentes et al. (AJR 188:331-333, 2007) and children Feins and Borger (AJR 188:331-333, 2007), Al-Ali et al. (Pediatr Radiol 27:287, 1997), and it is usually associated with bowel obstruction Siddins and Cade (Aust N Z J Surg 60:400-403, 1990), Tate (Am Surg 59:455-458, 1993), Chiavarini and Chang (Radiology 115:47-48, 1974), Cope and Levy (South Afr Med J 40:366-369, 1966), Sharov (Vestn Roentgenol Radiol 35:63-64, 1960), Fuentes et al. (AJR 188:331-333, 2007), Feins and Borger (AJR 188:331-333, 2007). We report a case of an incidental wandering liver in an adult without associated obstruction, diagnosed by multidetector computed tomography with multiplanar reformations.

CT enterography is a new imaging modality that has distinct advantages over conventional CT, wireless capsule endoscopy, and barium examination. CT enterography is noninvasive and allows rapid mapping of disease activity before endoscopy and in cases where the endoscope cannot reach the diseased segment. CT enterography is readily available, is operator independent, and allows evaluation of extraenteric complications of small bowel disease. This article describes the latest techniques and applications of CT enterography.

Intestinal ischemia and infarction are a heterogeneous group of diseases that have as their unifying theme hypoxia of the small bowel or colon. The incidence of bowel ischemia and infarction is on the rise for several reasons: the aging of the population, the ability of intensive care units to salvage critically ill patients, and heightened clinical awareness of these disorders. Improvements in diagnostic imaging techniques have greatly contributed to the earlier diagnosis of intestinal ischemia, which can have a positive influence on patient outcomes. In this article, role of radiology in the detection, differential diagnosis, and management of patients who have intestinal ischemia and infarction is discussed.

Intestinal ischemia and infarction are a heterogeneous group of diseases that have as their unifying theme hypoxia of the small bowel and/or colon. The incidence of bowel ischemia is increasing for a number of reasons: the aging of the population, the ability of intensive care units to salvage critically ill patients, and heightened clinical awareness of these disorders. Improvements in diagnostic imaging techniques have contributed greatly to the earlier diagnosis of intestinal ischemia, which can have a positive influence on patient outcomes. In this review, advances in multidetector computerized tomography, magnetic resonance, and ultrasound in the detection of intestinal ischemia are highlighted and placed in the context of expeditious patient management.

The purpose of this pictorial essay is to describe magnetic resonance (MR) imaging features of acute processes involving the bowel. While computed tomography (CT) is likely to remain the modality of choice in this setting, the advantages of MR include high soft tissue contrast, lack of ionizing radiation, and the ability to administer gadolinium in patients with a history of allergic reaction to iodinated contrast material. With the increasing utilization of abdominal/pelvic MR, radiologists must recognize the MR features of acute bowel pathology. Key MR findings of a variety of causes of acute abdominal pain are illustrated.

Radioembolization with yttrium 90 (90Y) microspheres represents an emerging transarterial therapy for the treatment of liver malignancies that continues to generate interest in the medical community. The classic indication of treatment response is a reduction in tumor size; however, parenchymal changes (eg, necrosis, lack of enhancement, specific findings at positron emission tomography and functional magnetic resonance imaging) and other benign findings (pleural effusions, perivascular edema, contralateral hypertrophy, ring enhancement, perihepatic fluid, fibrosis) may occur following treatment, requiring proper image interpretation. With classic imaging findings and surrogates (time to progression, duration of response, disease-free interval), response rates range from 20% to 80% in patients treated for hepatocellular carcinoma or metastatic disease to the liver. Complications of 90Y radioembolization include cholecystitis, abscess, and bilomas and should be recognized early in the imaging follow-up of these patients. Radiologists who are involved in the posttreatment assessment of patients undergoing 90Y radioembolization should be familiar with the imaging findings and potential imaging pitfalls associated with this therapy.

Fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) scanning is useful in evaluating suspicious lesions of the lung. Our patient was a 65-year-old woman with a 45-pack-year smoking history who was referred for further evaluation because of a 3 cm x 3 cm solid lung nodule on computed tomography scan of the chest. FDG-PET scan revealed a standard uptake value of 3.2 suggestive of malignancy. The histology of the lung nodule was consistent with lipoid pneumonia, a benign condition frequently associated with inadvertent aspiration or inhalation of oily substances.

The purpose of this study was to assess the feasibility of diagnosing appendicitis based on coronal reformations without the aid of transverse images. Abdominal and pelvic computed tomography (CT) scans of 53 patients (27 with appendicitis and 26 without appendicitis) were reviewed. All scans were obtained using a four-slice multi-detector row CT. The radiologists were not aware of the final diagnosis. Cases were reviewed for the visualization of the appendix and presence of appendicitis. All images were reviewed on picture archiving and communication systems. There were no false positives for diagnosing appendicitis when using either the transverse or coronal reformations. Appendicitis was not seen on the coronal images in one case, and there were no false negatives when transverse reformations alone were used. This difference was not statistically significant (p < 0.0001 for both modes of display). The sensitivity for diagnosing appendicitis based on the coronal images alone was 96%, the specificity was 100%, and the accuracy was 98%. Coronal reformations decreased the number of images reviewed by 19%. CT diagnosis of appendicitis based on the coronal images is accurate.

The feasibility of imaging pulsatility in an aneurysm model with the high-resolution dynamic multiscan technique of 64-slice computed tomography (CT) was studied. A pulsatile aneurysm phantom was constructed and imaged with dynamic multiscan technique. The aneurysm model was filled with iodinated contrast material (250 Hounsfield Units) and was scanned with use of a gantry rotation time of 0.33 seconds, slice thickness of 1.2 mm, effective coverage of 24 mm, and total imaging time of 4 seconds. Images were reconstructed at 50-msec intervals. The visualization of wall motion was qualitatively evaluated by direct comparison of four-dimensional images versus phantom motion. Pulsatility imaging without perceptible artifact or need for cardiac gating was achieved with the use of this technique.

Rationale and Objective: We sought to develop a Bayesian-filter that could distinguish positive radiology computed tomography (CT) reports of appendicitis from negative reports with no appendicitis., Materials and Methods: Standard unstructured electronic text radiology reports containing the key word appendicitis were obtained using a Java-based text search engine from a hospital General Electric PACS system. A total of 500 randomly selected reports from multiple radiologists were then manually categorized and merged into two separate text files: 250 positive reports and 250 negative findings of appendicitis. The two text files were then processed by the freely available UNIX-based software dbacl 1.9, a digramic Bayesian classifier for text recognition, on a Linux based Pentium 4 system. The software was then trained on the two separate merged text files categories of positive and negative appendicitis. The ability of the Bayesian filter to discriminate between reports of negative and positive appendicitis images was then tested on 100 randomly selected reports of appendicitis: 50 positive cases and 50 negative cases., Results: The training time for the Bayesian filter was approximately 2 seconds. The Bayesian filter subsequently was able to categorize 50 of 50 positive reports of appendicitis and 50 of 50 reports of negative appendicitis, in less than 10 seconds., Conclusion: A Bayesian-filter system can be used to quickly categorize radiology report findings and automatically determine after training, with a high degree of accuracy, whether the reports have text findings of a specific diagnosis. The Bayesian filter can potentially be applied to any type of radiologic report finding and any relevant category.

We describe an extremely rare case of an ileocolic intussusception with an appendiceal mucocele as the lead-point and cause of acute right lower quadrant pain in an adult patient. There are only few reported cases of this entity in the radiologic literature. We describe the multislice (computed tomography) CT features and emphasize the value of multiplanar reformations. We also discuss how specific findings on CT should allow for a correct preoperative diagnosis.

Objective: The purpose of this study was to describe the CT diagnosis of chyluria after partial nephrectomy., Conclusion: Fat in the bladder can be identified on CT after partial nephrectomy. This finding is caused by chyluria secondary to lymphatic injury and should not be mistaken for other abnormalities. Our study population did not need treatment of chyluria.

Feasibility of diagnosing small bowel obstruction on multidetector-row computed tomography (MDCT) using coronal reformations alone is evaluated. Three radiologists with subspecialty training in abdominal imaging reviewed abdominopelvic CT of 67 patients in consensus. Thirty-four patients had surgically proven small bowel obstruction. The remaining 33 patients had CT for other reasons and had no intestinal obstruction. The images were displayed in either axial or coronal planes and were reviewed on separate days . Each CT was evaluated for the presence of small bowel obstruction and its etiology when applicable. Thirty-three (100%) of 33 patients were correctly diagnosed not to have intestinal obstruction on coronal images. Thirty-four (100%) of 34 patients were correctly diagnosed to have small bowel obstruction on both forms of image display. There were five patients where the final surgical diagnosis for the etiology of small bowel obstruction did not agree with the interpretation of either the coronal or axial images; however, in all five patients, the interpretations of axial and coronal images were similar. In only one patient, the etiology of small bowel obstruction based on the coronal images did not agree with that of axial images and the surgical result; however, the site of small bowel obstruction was correctly diagnosed. There were approximately 20% fewer images in the coronal reformation data set, and the radiologists found review of these images to be easier for localizing the zone of transition in small bowel obstruction. Very high diagnostic accuracy can be achieved based on coronal reformations alone, and this form of image display may potentially be substituted for the conventional axial images. Since there are fewer images to review when the studies are displayed in coronal plane, this may positively impact radiologist workflow.

The purpose of this paper is to assess the incidence of visualization of the normal appendix on magnetic resonance imaging (MRI) examinations of the pelvis in a large adult population and to compare the yield of commonly used sequences. Pelvic MRI scans of 111 randomly selected patients were retrospectively reviewed by two fellowship-trained body imagers. Thirty-six cases, where the entire cecum and terminal ileum were not included in the field of view, were excluded. A normal appendix was definitively visualized in 55 of 71 patients on T1 spin echo (SE) sequences (78%). The appendix was seen on 25 of 42 (60%) half-Fourier single-shot turbo spin echo T2. Visualization rates were 42% on pre-gadolinium T1 FS GRE, 54% on post-gadolinium T1 fat-suppressed gradient echo, and 17% of short tau inversion recovery sequences. MRI is an effective modality for visualization of the normal appendix. This may have important implications in patients with abdominal or pelvic pain, as visualization of a normal appendix should exclude the possibility of acute appendicitis from the differential diagnosis.

Objectives: To determine the utility of multislice computed tomography (MSCT) technology to evaluate coronary stent luminal diameter., Background: Stent metal induced "blooming" artifact makes quantitative coronary angiography by MSCT difficult. There is a paucity of data on the efficacy of using 64 and 16 detector MSCT in evaluating coronary stents., Methods: We evaluated four commercially available bare metal and polymer coated drug eluting stents using 64 and 16 detector MSCT for the following: (1) Strut density in Hounsfield's Units (Hu) using a 2 mm MIP; (2) In-stent luminal diameter (ISLD) measured by MSCT compared to intravascular ultrasound (IVUS)., Results: Increased strut thickness did not correlate with greater strut density as measured in Hu (R(2) = 0.05, P = 0.29). The ISLD by 16 MSCT vs. IVUS is: Vision 1.63 +/- 0.58 mm vs. 2.8 +/- 0.0; Cypher 1.80 +/- 0.00 vs. 2.9 +/- 0.0; Taxus 1.87 +/- 0.58 vs. 2.9 +/- 0.0; Liberté 1.80 +/- 0.10 vs. 3.0 +/- 0.1 (P < 0.01). ISLD determined by 64 MSCT vs. IVUS is: Vision 1.73 +/- 0.06 mm vs. 2.8 +/- 0.0; Cypher 1.87 +/- 0.12 vs. 2.9 +/- 0.0; Taxus 1.77 +/- 0.06 vs. 2.9 +/- 0.0; Liberté 1.80 +/- 0.10 vs. 3.0 +/- 0.1 (P < 0.01)., Conclusions: When compared to IVUS measurements, MSCT results in a significant, underestimation of ISLD. This consistent underestimation (even with 64 MSCT) limits the applicability of CT angiography to quantify in-stent restenosis., (Copyright 2006 Wiley-Liss, Inc.)

Gastrointestinal carcinoid tumours are notoriously difficult to diagnose in the absence of the carcinoid syndrome. The clinical presentation is typically non-specific, and patients often go undiagnosed for years. Recent advances in computed tomography (CT), magnetic resonance (MR), endoscopic ultrasound, and nuclear scintigraphy have combined to improve the diagnosis and staging of this fascinating tumour. In this chapter the applications of cross-sectional imaging in patients with gastrointestinal carcinoid tumours is presented.

Rationale and Objectives: We describe a simple technique for transmission of a complete set of cranial computed tomography (CT) images to a commercially available wireless personal digital assistant (PDA) for remote teleradiology consultation., Materials and Methods: A complete set of images from the head CT of a trauma patient with subdural hematoma (19 images) was captured from a picture archiving and communication system and transmitted wirelessly as an e-mail attachment after being compressed. The images were retrieved, decompressed, and reviewed using commercially available software and a PDA with cellular phone capability., Results: A complete head CT was transmitted to a remote radiologist's wireless PDA for consultation. The entire procedure (including image capture, transmission, and review) took approximately 11.5 minutes., Conclusion: Using the technique described in this article the wireless PDA may function as a robust medium for facilitating care of brain trauma patients by allowing rapid access to trauma radiologists or neurosurgeons.

The objective of the study was to assess the feasibility of using a personal digital assistant (PDA) as a medium for the interpretation of cranial CT scans of trauma patients. Twenty-one noncontrast cranial CT scans were transferred in their entirety to a PDA from the picture archiving and communications system (PACS) utilizing General Electric (GE) PathSpeed PACS Web Server interface and synchronization. All CT scans had been interpreted by board-certified radiologists prior to the study. Seven of the scans demonstrated subarachnoid hemorrhage, seven demonstrated subdural hematomas, and the remaining scans were normal. After transfer to the PDA, all images were separately reviewed in a blinded manner by a radiologist and a neurosurgeon. Images were graded for their quality and diagnostic utility in the evaluation of intracranial hemorrhage. Image quality was categorized as excellent, very good, acceptable for diagnosis, or not acceptable for diagnosis. Based on the radiologic diagnosis, recommendation for surgical management was made by the reviewing neurosurgeon. The accuracy rate for both the radiologist and the neurosurgeon in the detection of intracranial hemorrhage was 95%. There was one false negative which was attributed to error in judgment rather than poor image quality. This diagnostic error did not affect patient management. The sensitivity and specificity for detection of intracranial hemorrhage were 93% and 100%, respectively. Image quality was judged to be excellent in 90% of the cases and very good in the remaining 10%. Our results suggest that the PDA is a robust medium for interpretation of CT scans in patients with suspected hemorrhage following intracranial injury. In this setting, the PDA should be considered for teleradiology purposes.

This article reviews the imaging of various benign and malignant diseases of the gallbladder. Clinical findings and imaging features using ultrasound, CT, and MR for the detection and evaluation of gallstones, acute cholecystitis, xanthogranulomatous cholecystitis, adenomyomatosis, and carcinoma of the gallbladder among other disorders are discussed.