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OBJECTIVE. Previous advances over filtered back projection (FBP) have incorporated model-based iterative reconstruction. The purpose of this study was to characterize the latest advance in image reconstruction, that is, deep learning. The focus was on applying characterization results of a deep learning approach to decisions about clinical CT protocols. MATERIALS AND METHODS. A proprietary deep learning image reconstruction (DLIR) method was characterized against an existing advanced adaptive statistical iterative reconstruction method (ASIR-V) and FBP from the same vendor. The metrics used were contrast-to-noise ratio, spatial resolution as a function of contrast level, noise texture (i.e., noise power spectra [NPS]), noise scaling as a function of slice thickness, and CT number consistency. The American College of Radiology accreditation phantom and a uniform water phantom were used at a range of doses and slice thicknesses for both axial and helical acquisition modes. RESULTS. ASIR-V and DLIR were associated with improved contrast-to-noise ratio over FBP for all doses and slice thicknesses. No dose or contrast dependencies of spatial resolution were observed for ASIR-V or DLIR. NPS results showed DLIR maintained an FBP-like noise texture whereas ASIR-V shifted the NPS to lower frequencies. Noise changed with dose and slice thickness in the same manner for ASIR-V and FBP. DLIR slice thickness noise scaling differed from FBP, exhibiting less noise penalty with decreasing slice thickness. No clinically significant changes were observed in CT numbers for any measurement condition. CONCLUSION. In a phantom model, DLIR does not suffer from the concerns over reduction in spatial resolution and introduction of poor noise texture associated with previous methods.

Background: Complement activation in kidney transplantation is implicated in the pathogenesis of delayed graft function (DGF). This study evaluated the therapeutic efficacy of high-dose recombinant human C1 esterase inhibitor (rhC1INH) to prevent DGF in a nonhuman primate model of kidney transplantation after brain death and prolonged cold ischemia. Methods: Brain death donors underwent 20 h of conventional management. Procured kidneys were stored on ice for 44-48 h, then transplanted into ABO-compatible major histocompatibility complex-mismatched recipients. Recipients were treated with vehicle (n = 5) or rhC1INH 500 U/kg plus heparin 40 U/kg (n = 8) before reperfusion, 12 h, and 24 h posttransplant. Recipients were followed up for 120 d. Results: Of vehicle-treated recipients, 80% (4 of 5) developed DGF versus 12.5% (1 of 8) rhC1INH-treated recipients (P = 0.015). rhC1INH-treated recipients had faster creatinine recovery, superior urinary output, and reduced urinary neutrophil gelatinase-associated lipocalin and tissue inhibitor of metalloproteinases 2-insulin-like growth factor-binding protein 7 throughout the first week, indicating reduced allograft injury. Treated recipients presented lower postreperfusion plasma interleukin (IL)-6, IL-8, tumor necrosis factor-alpha, and IL-18, lower day 4 monocyte chemoattractant protein 1, and trended toward lower C5. Treated recipients exhibited less C3b/C5b-9 deposition on day 7 biopsies. rhC1INH-treated animals also trended toward prolonged mediated rejection-free survival. Conclusions: Our results recommend high-dose C1INH complement blockade in transplant recipients as an effective strategy to reduce kidney injury and inflammation, prevent DGF, delay antibody-mediated rejection development, and improve transplant outcomes.

Delayed graft function (DGF) in renal transplant is associated with reduced graft survival and increased immunogenicity. The complement-driven inflammatory response after brain death (BD) and posttransplant reperfusion injury play significant roles in the pathogenesis of DGF. In a nonhuman primate model, we tested complement-blockade in BD donors to prevent DGF and improve graft survival. BD donors were maintained for 20 hours; kidneys were procured and stored at 4 degrees C for 43-48 hours prior to implantation into ABO-compatible, nonsensitized, MHC-mismatched recipients. Animals were divided into 3 donor-treatment groups: G1 - vehicle, G2 - rhC1INH+heparin, and G3 - heparin. G2 donors showed significant reduction in classical complement pathway activation and decreased levels of tumor necrosis factor alpha and monocyte chemoattractant protein 1. DGF was diagnosed in 4/6 (67%) G1 recipients, 3/3 (100%) G3 recipients, and 0/6 (0%) G2 recipients (P = .008). In addition, G2 recipients showed superior renal function, reduced sC5b-9, and reduced urinary neutrophil gelatinase-associated lipocalin in the first week posttransplant. We observed no differences in incidence or severity of graft rejection between groups. Collectively, the data indicate that donor-management targeting complement activation prevents the development of DGF. Our results suggest a pivotal role for complement activation in BD-induced renal injury and postulate complement blockade as a promising strategy for the prevention of DGF after transplantation.

The purpose of this paper is to describe our experience with the AAPM Medical Physics Practice Guideline 1.a: “CT Protocol Management and Review Practice Guideline”. Specifically, we will share how our institution's quality management system addresses the suggestions within the AAPM practice report. We feel this paper is needed as it was beyond the scope of the AAPM practice guideline to provide specific details on fulfilling individual guidelines. Our hope is that other institutions will be able to emulate some of our practices and that this article would encourage other types of centers (e.g., community hospitals) to share their methodology for approaching CT protocol optimization and quality control. Our institution had a functioning CT protocol optimization process, albeit informal, since we began using CT. Recently, we made our protocol development and validation process compliant with a number of the ISO 9001:2008 clauses and this required us to formalize the roles of the members of our CT protocol optimization team. We rely heavily on PACS‐based IT solutions for acquiring radiologist feedback on the performance of our CT protocols and the performance of our CT scanners in terms of dose (scanner output) and the function of the automatic tube current modulation. Specific details on our quality management system covering both quality control and ongoing optimization have been provided. The roles of each CT protocol team member have been defined, and the critical role that IT solutions provides for the management of files and the monitoring of CT protocols has been reviewed. In addition, the invaluable role management provides by being a champion for the project has been explained; lack of a project champion will mitigate the efforts of a CT protocol optimization team. Meeting the guidelines set forth in the AAPM practice guideline was not inherently difficult, but did, in our case, require the cooperation of radiologists, technologists, physicists, IT, administrative staff, and hospital management. Some of the IT solutions presented in this paper are novel and currently unique to our institution. PACS number: 87.57.Q

Purpose Quantification of the frequency, understanding the motivation, and documentation of the changes made by CT technologists at scan time are important components of monitoring a quality CT workflow. Methods CT scan acquisition data were collected from one CT scanner for a period of 1 year. The data included all relevant acquisition parameters needed to define the technical side of a CT protocol. An algorithm was created to sort these data in groups of irradiation events with the same combinations of scan acquisition parameters. For scans modified at scan time, it was hypothesized that these examinations would show up only once in the organized data. A classification scheme was developed to place each "one-off" examination into a category related to what motivated the scan-time change. Results A total of 132,707 irradiation events were organized into 434 groups of unique scan acquisition parameters. One hundred forty-four irradiation events had acquisition parameters that showed up only once in the data. These "one-offs" were classified as follows: 25% represented rarely used protocols, 17% were due to service scans, 16% were changed for unknown and therefore undesired reasons, 15% were changed by technologists trying to adapt protocol to patient size, 12% were allowable scan-time changes, 8% of scans had tube current maxed out, and 6% of scans were changed to a higher dose mode as requested by radiologists. Conclusions The outcome of this study suggests many areas of needed technologist training and chances for optimizing this institution's CT protocols.

We compared the reproducibility of automated volume and manual linear measurements using same study supine and prone, low dose, noncontrast computerized tomography series.The patient cohort comprised 50 consecutive adults with a mean age of 56.4 years in whom renal calculi were identified during computerized tomography colonography screening. The largest stone per patient was assessed with the supine and prone computerized tomography series serving as mutual controls. Automated stone volume was derived using a commercially available coronary artery calcium scoring tool. Supine-prone reproducibility for automated volume was compared with intra-observer supine-prone manual linear measurement. Interobserver variability was also assessed for manual linear measurements of the same supine or prone series.Mean ± SD linear size and volume of the 50 index calculi was 4.5 ± 2.7 mm (range 1.8 to 16) and 141.7 ± 456.1 mm(3), respectively. The mean supine-prone error for automated stone volume was 16.3% compared with an average 11.7% 1-dimensional intra-observer error for manual axial measurement. Only 2 of 15 cases with a volume error of greater than 20% were 5 mm or greater in linear size. The average interobserver linear error for the same computerized tomography series was 26.3% but automated volume measurement of the same series did not vary.Automated noncontrast computerized tomography renal stone volume is more reproducible than manual linear size measurement and it avoids the often large interobserver variability seen with manual assessment. Since small linear differences correspond to much larger volume changes, greater absolute volume errors are acceptable. Automated volume measurement may be an improved clinical parameter to use for following the renal stone burden.

A pseudoaneurysm is an infrequent complication of arterial intervention. It is most frequently seen in the groin after coronary catheterization but can be seen in any vessel as a sequela of trauma. Pseudoaneurysms can also occur peripherally as the sequela of arteriovenous shunting for dialysis or placement of indwelling catheters or after traumatic drawing of arterial blood gas. Treatment of pseudoaneurysms has evolved through the years. Initially it was the domain of surgical intervention. Subsequently, most cases have been treated with ultrasound-guided compression. Recently thrombin (Jones Pharmacy Inc, St Louis, MO) injection has become the preferred treatment method. However, direct injection of thrombin into a pseudoaneurysm is not without risk. If thrombin should escape the pseudoaneurysm, a clot can propagate into the affected artery and result in embolization or thrombosis of peripheral branch vessels. The severity of the iatrogenic insult is amplified when the blood supply is to more critical areas, such as the head or hand. In this report, a new technique to help minimize the chance of unwanted propagation of the thrombus into the peripheral vasculature during thrombin treatment of a radial artery pseudoaneurysm is described.

Objective. We have advanced the application of intraoperative neurosonography by combining gray scale sonographic imaging with pulsed wave Doppler and color flow Doppler imaging to guide and confirm resection of arteriovenous malformations of the brain. We want to share our technique with the imaging community. Methods. We present a review of our scan technique as it has evolved over the 3 years during which we have been assisting our neurosurgical team. Results and Conclusions. Our experience has indicated that a combination of sonographic imaging and color and spectral Doppler imaging improves surgical resection of such lesions.

The purpose of this study was to compare hepatic tumor conspicuity on CT after injection of either 150 mL of contrast material or 100 mL of contrast material plus a 50-mL saline chaser.We evaluated 86 hypoattenuating liver metastases in 26 patients. Patients underwent CT in two sessions separated by a mean of 85 days: one time with 150 mL of contrast material and the other time with 100 mL of contrast material followed by a 50-mL saline chaser. The order of the sessions was randomized. Contrast material was administered via power injector and matched for injection rate and delay time. Attenuation values were obtained from normal liver tissue and metastases and from the spleen, kidney, aorta, and inferior vena cava.The 150 mL dose of contrast material caused slightly greater liver and tumor attenuation than 100 mL of contrast material with a chaser (mean hepatic attenuation, 95.6 vs 89.8 H, respectively; p0.03, paired t test; mean tumor attenuation, 53.2 vs 49.1 H, respectively; r = 0.71, p = 0.09). The difference in conspicuity of liver lesions was slightly greater with 150 mL than with 100 mL with a chaser (46.8 H vs 44.2 H; r = 0.46, p = 0.08, paired t test), but was of doubtful clinical significance (2.6 H). Kidney, spleen, and vascular structures enhanced more with 150 mL than with 100 mL and a chaser.Using 100 mL of contrast material and a saline chaser did not result in a meaningful difference in liver parenchyma attenuation or lesion conspicuity compared with using 150 mL of contrast medium alone. Routine use of a chaser for abdominal CT may yield cost savings and a decreased risk of contrast nephropathy.

Objectives. Several investigators have evaluated noncontrast computed tomography (NCCT) in predicting stone composition in vitro. We assessed NCCT in predicting stone composition in patients presenting to our emergency room with flank pain and stone disease. Methods. One hundred twenty-nine patients presenting to our university hospital with flank pain underwent renal colic protocol NCCT scans at the request of the emergency room physicians. A General Electric, high-speed advantage CT scanner was used at 120 kV, 200 mA, and 1.4:1 pitch, with collimation varying between 3 and 5 mm. Ninety-nine patients with predominantly (greater than 50%) calcium oxalate or uric acid composition after either stone passage or stone removal were identified. Each scan was analyzed by one of two radiologists, who determined the predominant attenuation for each stone. Stones once passed or retrieved were analyzed by Urocor Laboratories. The attenuation and attenuation/size ratio (peak attenuation/size in millimeters) were compared with the results of the stone analysis. Results. Eighty-two calculi predominantly composed of calcium oxalate and 17 calculi predominantly composed of uric acid were identified in 99 patients. The calculi ranged in size from 1 to 28 mm. A significant difference (P = 0.017, unpaired t test) was found between the Hounsfield measurement of uric acid calculi (mean 344 ± 152 HU) and the Hounsfield measurement of calcium oxalate calculi (mean 652 ± 490 HU). If only the Hounsfield units from stones 4 mm or larger were compared, the data were even more compelling (P = 0.002). However, using an attenuation/size ratio cutoff of greater than 80, the negative predictive value was 99% that a stone would be predominantly calcium oxalate. Conclusions. Using peak attenuation measurements and the attenuation/size ratio of urinary calculi from NCCT, we were able to differentiate between uric acid and calcium oxalate stones.

Renal transplantation has grown rapidly over the past 30 years, resulting in an inadequate supply of organs to meet the ever-increasing demand. This has led to an increase in the number of living-related donors. Advances in imaging technology now allow safe, rapid, and relatively noninvasive evaluation of potential donors. Helical computed tomographic (CT) angiography is a fast, minimally invasive procedure that is quickly becoming the imaging modality of choice for preoperative evaluation of potential renal transplant donors. Helical CT, combined with low-osmolar intravenous contrast materials, has enabled CT angiography to depict arterial and venous anatomy accurately. Between July 1995 and March 1997, CT angiography was performed in 205 potential renal donors. Correlation with surgical findings in 136 donor nephrectomies helped confirm a high level of accuracy for CT angiography in the assessment of the renal vasculature: Sensitivity and specificity for identifying specific vessels was 99.6% and 99.6% for main renal arteries, 76.9% and 89.9% for polar arteries, and 98.7% and 95.5% for main renal veins, respectively. CT angiography allows the radiologist to provide the transplant surgeon with precise preoperative anatomy of the renal vasculature, thus reducing the risks and complications associated with the harvesting procedure and improving the chances for a successful outcome. However, accurate radiologic interpretation depends on the radiologist's experience level, attention to detail, and commitment to careful image evaluation.

We report a case of a patient with portal hypertension secondary to alcoholic cirrhosis (Child's Class C) who initially presented with a colovaginal fistula secondary to acute sigmoid diverticulitis. The patient had a prior history of hepatic cirrhosis with ascites, coagulopathy, and portal hypertension. Computed tomography of the abdomen and pelvis demonstrated a large diverticular phlegmon and ascites. Computed tomographic angiography demonstrated a large left anterior abdominal wall varix in the region of the anticipated sigmoid resection. Three-dimensional reconstruction of the computed tomographic angiography further delineated the path of this large varix, confirming the increased risk from surgical intervention. Following initial conservative treatment with intravenous antibiotics, parenteral nutrition, and percutaneous abscess drainage, a transjugular intrahepatic portosystemic shunt procedure was performed to decompress the portal system varices. A repeat computed tomographic scan with three-dimensional reconstruction confirmed decompression of the varix. A successful sigmoid resection was subsequently performed. Preoperative computed tomographic angiography with three-dimensional reconstruction is a useful adjunct in planning the operative strategy in patients with complex intraabdominal pathology and collateral portovenous flow secondary to portal hypertension.

Malignant testicular tumors are an important clinical problem, and ultrasound is the most frequently ordered imaging modality once a palpable scrotal mass is discovered. Numerous articles discussing the role of ultrasound in the evaluation of testicular pathology have confirmed the value of preoperative imaging. This article presents a review of imaging literature regarding testicular neoplasms, with an emphasis on correlation of gross and microscopic tumor pathology and imaging findings. Also included are sections on anatomy, epidemiology, histogenesis, and tumor markers.

We compared color Doppler velocity sonography and color Doppler energy sonography for the diagnosis of spermatic cord torsion in a canine model and determined the degree of torsion necessary to acutely halt testicular blood flow.Spermatic cord torsion was created in five dogs by exposing and rotating the ipsilateral testis 0 degree, 180 degrees, 270 degrees, 360 degrees, 450 degrees, and 540 degrees. Detorsion followed. The testicles were scanned at each torsion stop using both color Doppler velocity sonography and color Doppler energy sonography. Doppler parameters were optimized (by phantom and test scans) and maintained at a tolerable noise level throughout the experiment. Readers who were unaware of the degree of torsion compared flow in the rotated and contralateral control testes.Flow became undetectable by color Doppler velocity sonography and color Doppler energy sonography at 450 degrees in four of five cases and at 540 degrees in one of five cases. We found no significant difference between the velocity and the energy techniques for detecting this absence of flow (p.05, Wilcoxon test). We found a significant difference in degree of flow for both techniques when comparing controls and all degrees of torsion combined (p.006, Mann-Whitney test), but significance was achieved at lesser degrees of torsion with the velocity technique than with the energy technique (180 degrees and 360 degrees, respectively, Wilcoxon test).Color Doppler energy sonography was not significantly more sensitive than color Doppler velocity sonography for the diagnosis of spermatic cord torsion in this model. Complete occlusion of arterial inflow occurred at 450-540 degrees of torsion.

Background. Splenomegaly in patients with cancer raises the suspicion of tumor involvement. Splenic enlargement in the absence of splenic metastases, however, has been reported in patients treated with interleukin-2 (IL-2) immunotherapy. This study characterizes the change in spleen size that occurred in 42 patients treated with IL-2 between 1989 and 1993 for nonhematologic malignancies. Methods. Computed tomography (CT) scans before and during immunotherapy were available for review on all 42 patients and after immunotherapy on 16 of these patients. The splenic index was measured for each CT by a single reader blinded to the time course of IL-2 therapy. Results. Mean splenic index increased 64.1% from 646 cm 3 (standard deviation [SD], 387) pre-IL-2 to 1059 cm 3 (SD, 534) during therapy with IL-2 (P < 0.0001). The splenic index remained elevated at 1112 cm 3 (SD, 633) after completion of IL-2 therapy. Conclusions. Splenomegaly, temporally associated with IL-2 therapy for nonhematologic malignancies, is likely to represent a sequela of therapy and not tumor progression

There is growing concern over the long-term radiation exposure from serial computed tomographic (CT) scan follow-up after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs). Screening for endoleaks with non-contrast-enhanced volumetric CT has been shown to significantly reduce radiation doses. We evaluated the use of NCT as the primary method of follow-up after EVAR of AAAs.Our institutional post-EVAR CT protocol consisted of contrast-enhanced CT angiography (CTA) 1 month after repair, followed by NCT at 3 or 6 and 12 months, and annually thereafter. At each follow-up scan, immediate 3-dimensional volume analysis was performed. If the volume change was2%, NCT follow-up was continued. If the volume increased by ≥2% on nonenhanced images, contrast-enhanced CT was performed immediately to identify potential endoleaks. All images were reviewed by an experienced cardiovascular radiologist. End points included identification of endoleak, reintervention, and rupture.Over a 7-year period, 126 patients were followed. Serial CTA was performed in 59 patients, while 67 patients were followed with the NCT protocol. The mean follow-up was 2.07 years. There were no differences in age, sex, or initial aneurysm volume or size. There were 35 total endoleaks identified. Twenty of these were early endoleaks (30 days post-EVAR). The remaining 15 leaks were late in nature (10 in the contrast group and 5 in the noncontrast group; P=0.17). NCT aneurysm sac volume changes prompted contrasted studies in all 5 late leaks. The mean volume change was 11.2 cm3, an average change of 5.88%. These findings were not significantly different than the late leaks found by routine contrast studies (8.9 cm3; 4.98% [P=0.58]). There were no delayed ruptures or emergent reinterventions in the NCT group.Serial NCT appears to be safe and effective as the sole means of follow-up after EVAR for AAAs. AAA volume increases of ≥2% should prompt further contrast-enhanced CT imaging. Changes of2% can be safely followed with serial NCT. This protocol requires dedicated cardiovascular radiologist involvement, and patients should be retained in the radiology suite until real-time image evaluation can be completed.

Results of studies on the accuracy of the resistive index as a predictor of acute renal transplant rejection have varied widely. Clinical evaluations are limited by the inability to control the numerous coincidental factors that affect vascular resistance. We performed a controlled study in dogs to isolate the effects of acute tubular necrosis, cyclosporine toxicity, and acute rejection on the resistive index, and to compare them with a population of normal control subjects. By doing so, we hoped to identify the patterns of change in the resistive index over time and possibly explain the wide spectrum of resistive index data reported in the literature. Resistive index, a parameter calculated from relative systolic and diastolic velocity, indicates parenchymal resistance to perfusion. Since an increase in renal length also has been reported useful in predicting rejection, we studied changes in length in each of the isolated conditions. The normal control group (four dogs) had heterotopic autotransplantation with minimal cold ischemic time. The acute tubular necrosis group (six dogs) had heterotopic autotransplantation with 1 hr of warm ischemic time. The cyclosporine toxicity group (four dogs) was allowed approximately 3 months to heal from heterotopic autotransplantation. Very high (toxic) doses of cyclosporine were then administered. The acute rejection group (five dogs) had heterotopic allografting with minimal cold ischemic time. No medications were administered. In all groups, the abnormalities induced were confirmed by biopsy. Creatinine levels were also used to monitor cyclosporine toxicity. In the normal control and acute tubular necrosis groups, resistive index increased immediately after surgery, returning to baseline within 10 days. Renal length increased slightly in both groups, but the duration of increase was longer in the acute tubular necrosis group. No significant change in resistive index or renal length was seen in the cyclosporine toxicity group. In the acute rejection group, an initial decrease in resistive index during the mild to moderate phase was followed by a rapidly progressive increase with worsening rejection. Renal length increased progressively beginning immediately after surgery. Our study determined the patterns of change in resistance and renal length over time as caused by the isolated pathologic states. Our finding that vascular resistance decreased in mild to moderate acute rejection was unexpected, since almost all the literature reports resistive index elevation. This may explain some of the conflicting results obtained in Doppler investigations of rejection. Our results on renal length reinforce the positive clinical reports of its predictive value in rejection.

Intermittent claudication may occur in well-conditioned athletes because of an unusual form of popliteal artery entrapment that results from overtraining. These patients complain of calf muscle cramping, rapid limb fatigue, and occasional paresthesias on the plantar surface of the foot when running on inclines or when repetitive jumping is performed. Results of plethysmographic screening tests for popliteal entrapment are positive in these patients. Magnetic resonance angiography and intravenous digital subtraction angiography studies, however, do not demonstrate findings typical of anatomic popliteal entrapment. No evidence exists of aberrant positioning of the popliteal artery in foot neutral positioning, but with forced plantar flexion, the neurovascular bundle is deviated and compressed laterally. Surgical exploration of the popliteal fossa demonstrates no obvious musculotendinous abnormality. Symptoms of claudication and arterial compression are relieved by surgical release of the soleus muscle from its tibial attachments, resection of its fascial band, and resection of the plantaris muscle.

Artifacts in spectral and color Doppler imaging can be confusing and lead to misinterpretation of flow information. The authors review these artifacts by considering three main causes: inappropriate equipment settings, anatomic factors, and physical and technical limitations of the modality. Incorrect gain, wall-filter, or velocity scale settings can cause loss of clinically important information or distortion of the tracing. Reflection of the Doppler signal from highly reflective surfaces can create a color Doppler mirror image. Vascular motion can introduce artifactual variation in velocity as the sample volume passes through different velocities in a laminar flow state. Unintentional motion can cause a generalized Doppler shift. Increasing the angle of Doppler interrogation degrades the quality of the tracing and gives the impression of spectral broadening. As angulation approaches 90 degrees, directional ambiguity can occur, suggesting bidirectional flow. Grating and side lobes can interrogate areas unrelated to the sample volume and introduce extraneous Doppler information to the apparent area of interrogation. Recognition of these artifacts is essential to proper interpretation of Doppler information and rendering a correct diagnosis.

To evaluate the clinical usefulness of volumetric analysis at nonenhanced computed tomography (CT) as the sole method with which to follow up endovascular abdominal aortic aneurysm repair (EVAR) and to identify endoleaks causing more than 2% volumetric increase from the previous volume determination.The study had institutional review board approval. Images were reviewed retrospectively in a HIPAA-compliant manner for 230 CT studies in 70 patients (11 women, 59 men; mean age, 74 years) who underwent EVAR. The scannning protocol consisted of three steps: (a) contrast material-enhanced CT angiography before endovascular stent placement, (b) contrast-enhanced CT angiography 0-3 months after repair to depict immediate complications, and (c) nonenhanced CT at 3, 6, and 12 months after repair. At each follow-up visit, immediate aortic volume analysis was performed. If the interval volumetric change was 2% or less, no further imaging was performed. If the volume increased by more than 2% on the nonenhanced CT image, contrast-enhanced CT angiography was performed immediately to identify the suspected endoleak. Confidence intervals (CIs) were obtained by using bootstrapping to account for repeated measurements in the same patients.Mean volume decrease was -3.2% (95% CI: -4.7%, -1.9%) in intervals without occurrence of a clinically relevant endoleak (n = 183). Types I and III high-pressure endoleaks (n = 10) showed a 10.0% (95% CI: 5.0%, 18.2%) interval volumetric increase. Type II low-pressure endoleaks (n = 37) showed a 5.4% (95% CI: 4.6%, 6.2%) interval volumetric increase. Endoleaks associated with minimal aortic volume increase of less than 2% did not require any intervention. This protocol reduced radiation exposure by approximately 57%-82% in an average-sized patient.Serial volumetric analysis of aortic aneurysm with nonenhanced CT serves as an adequate screening test for endoleak, causing volumetric increase of more than 2% from the volume seen at the previous examination.

The reported incidence of contrast-induced acute kidney injury varies widely. Almost no studies have been conducted to quantify the background fluctuation of kidney function of patients receiving iodinated contrast medium. The purpose of this study was a retrospective comparison of the incidence of acute kidney injury among patients undergoing CT with low-osmolar (iohexol) or isoosmolar (iodixanol) contrast medium with the incidence among patients undergoing CT without contrast administration.Creatinine concentration and estimated glomerular filtration rate were evaluated for 11,588 patients. Rates of acute kidney injury (defined as a 0.5 mg/dL increase in serum creatinine concentration or a 25% or greater decrease in estimated glomerular filtration rate within 3 days after CT) were compared among groups and stratified according to creatinine concentration and estimated glomerular filtration rate before the imaging examination.In all groups, the incidence of acute kidney injury increased with increasing baseline creatinine concentration. No significant difference in incidence of presumed contrast-induced kidney injury was identified between the isoosmolar contrast medium and the control groups. The incidence of acute kidney injury in the low-osmolar contrast medium cohort paralleled that of the control cohort up to a creatinine level of 1.8 mg/dL, but increases above this level were associated with a higher incidence of acute kidney injury.We identified a high incidence of acute kidney injury among control subjects undergoing unenhanced CT. The incidence of creatinine elevation in this group was statistically similar to that in the isoosmolar contrast medium group for all baseline creatinine values and all stages of chronic kidney disease. These findings suggest that the additional risk of acute kidney injury accompanying administration of contrast medium (contrast-induced nephrotoxicity) may be overstated and that much of the creatinine elevation in these patients is attributable to background fluctuation, underlying disease, or treatment.

Five patients with thrombosis of the main portal vein underwent Doppler ultrasound (US). Three of these patients had confirmed hepatocellular carcinoma. Doppler US allowed differentiation between bland thrombus and tumor thrombus in two of the three patients. Tumor thrombus of the main portal vein was characterized at US by an intraportal arterial waveform in a hepatofugal direction.

Chemotherapy by direct hepatic arterial infusion (HAI) results in reduction in tumor mass in a large percentage of patients. The authors reviewed records for 45 patients with metastatic cancer of the gastrointestinal tract who underwent HAI chemotherapy with floxuridine, administrated via an implanted pump. Twenty-seven of the 45 patients suffered complications, including gastrointestinal ulceration (18%), hepatitis (24%), sclerosing cholangitis (7%), and abscess (2%). The complication rates in this series were similar to those previously reported. The toxicity of HAI chemotherapy continues to limit its efficacy.

Renal transplantation patients undergoing biopsy were examined with duplex Doppler sonography to establish the sensitivity and specificity of this technique in the detection of rejection. The study population consisted of 89 consecutive patients, who received renal transplants 1 week to 17 years before our examination and underwent 96 core needle biopsies within 24 hr of sonography. The resistive index (RI), defined as the difference between the peak systolic and end diastolic flow velocities divided by the peak systolic velocity (expressed as a percentage), was measured in the main, segmental, interlobar, and arcuate renal arteries. Furthermore, the prominence of the renal pyramids, as determined by their size and echogenicity, was prospectively evaluated. Biopsy was used to establish diagnosis, but in cases of equivocal results, hospital course was the final arbiter. The most frequent diagnoses in the patients were acute rejection (41 patients) and chronic rejection (19 patients). Receiver-operating-cha...

We studied the value of transperineal sonography in the preoperative assessment of seven patients with clinically suspected vaginal atresia. Although transabdominal scanning is useful to determine if hydrocolpos or hydrometrocolpos is present, this method does not allow measurement of the thickness of a caudally placed obstructive septum. This information is useful in planning reconstructive surgery. All seven patients had transabdominal sonography, with five showing a low-lying obstruction. In those five patients, the distance between the perineal surface and the caudal aspect of the distended vagina, measured with electronic calipers on the transperineal sonograms, ranged from 1.0 to 4.0 cm. We conclude that when vaginal atresia is clinically suspected, transabdominal sonography should be performed to confirm the diagnosis. When a low-lying obstruction is identified, transperineal sonography should be performed to determine the length of the obstructive segment.

We have successfully applied sequential volumetric analysis of abdominal aortic aneurysms to exclude endoleak in patients who have an aortic endostent. This study compared the effect of variable operator experience on volumetric calculation accuracy.Four operators with different experience levels calculated abdominal aneurysm volumes in 10 patients at two different times (/= 1 week apart). The four reviewers were ranked as having a high level of experience (one full-time laboratory worker specializing in three dimensions with 3 years of experience), a moderate level of experience (one part-time laboratory worker specializing in three dimensions/computed tomographic technician with 1 year of part-time experience), and a low level of experience (two individuals taught volumetric measurements for the purposes of this study: a fellow in abdominal imaging and a computed tomographic technician). All volumes were calculated with a GE Advantage 4.0 workstation (General Electric, Waukesha, WI, USA).Mean aneurysm volume and volume difference between two measurements were calculated for four operators. The average (standard deviation) percent volume differences were 1.2% (0.2%) for the experienced reader, 3.2% (0.3%) for the moderately experienced reader, and 6.0% (1.0%) and 5.8% (1.1%) for the two readers with light experience. Differences between averages were statistically significant (p0.005).We have defined a percent margin of error for aortic aneurysm volume measurement and have shown a direct correlate to level of experience. Diagnosis of endoleak based on aneurysm volume enlargement on serial scans needs to account for the level of operator experience.

Atwinkling artifact manifests when crystalline material or rough surfaces are interrogated with Color Doppler sonography. 1,2 It has primarily been described as occurring with urinary tract calculi but can also be seen with biliary calculi and any material with an irregularly reflective, granular surface, such as iron filings, emery paper, ground chalk, and recently encrusted stents. 3 Twinkling has been studied to determine whether its presence can predict the chances of successful urinary tract stone fragmentation with lithotripsy. 1 We report a patient with a twinkling artifact emanating from an erroneously placed intravesicular Proline suture after bladder neck suspension surgery.

The purpose of this study was to examine muscle morphological and neural activation adaptations resulting from the interaction between concurrent strength and endurance training.Thirty sedentary healthy male subjects were randomly assigned to one of three training groups that performed 10 wk of 3-d x wk(-1) high-intensity strength training (S), cycle endurance training (E), or concurrent strength and endurance training (CC). Strength, quadriceps-muscle biopsies, computed tomography scans at mid-thigh, and surface electromyogram (EMG) assessments were made before and after training.S and CC groups demonstrated similar increases (P0.0001) in both thigh extensor (12 and 14%) and flexor/adductor (7 and 6%) muscle areas. Type II myofiber areas similarly increased (P0.002) in both S (24%) and CC (28%) groups, whereas the increase (P0.004) in Type I area with S training (19%) was also similar to the nonsignificant (P = 0.041) increase with CC training (13%). Significant increases (P0.005) in maximal isometric knee-extension torque were accompanied by nonsignificant (Por= 0.07) increases in root mean squared EMG amplitude of the quadriceps musculature for both S and C groups. No changes (P0.38) in the EMG/torque relation across 20 to 100% maximal voluntary contractions occurred in any group. A small 3% increase (P0.01) in thigh extensor area was the only change in any of the above variables with E training.Findings indicate 3-d x wk(-1) concurrent performance of both strength and endurance training does not impair adaptations in strength, muscle hypertrophy, and neural activation induced by strength training alone. Results provide a physiological basis to support several performance studies that consistently indicate 3-d x wk(-1) concurrent training does not impair strength development over the short term.

Spontaneous portosystemic shunts (varices) are a well-known complication of severe liver disease and portal hypertension. Computed tomographic (CT) angiography was used to image the hepatic vasculature of 198 patients with end-stage liver disease in anticipation of liver transplantation. Performance of a delayed acquisition during the portal phase of enhancement enables evaluation of portal and variceal anatomy without the need for an additional injection of contrast material. Three-dimensional (3D) reconstruction of portal-phase CT angiograms enhances the perception of the courses and anatomic relationships of varices. This information is valuable for surgical planning. Common varices include the left gastric vein, short gastric veins, paraumbilical veins, and splenic vein; in cases of more unusual, complex shunts, 3D rendering is indispensable. By precisely demonstrating the courses of varices, CT angiography allows the surgeon to plan the operative approach and determine the need for surgical varix ligation or preoperative interventional embolization.

Donor-derived malignancy (the inadvertent transmission of a tumor from the donor to the transplant recipient) is a rare phenomenon. We present an imaging report showing transmission of small-cell lung cancer from the donor to the recipient via a transplanted kidney.

Objective: Central venous catheterization is commonly performed in the critically ill. The femoral vein is widely accepted as an insertion site with complications thought to be comparable to other central access sites. We used serial ultrasound examinations with Doppler to examine the evolution of a heretofore undescribed complication of femoral vein catheterization, phlegmasia cerulea dolens with compartment syndrome. Design: Serial ultrasounds were performed in patients before the insertion of femoral venous catheters and sequentially every 48 hrs while the catheters were in place. The noncatheterized leg served as a control. Setting: A trauma and life support center of a tertiary multidisciplinary critical care unit. Patient: A 32-yr-old man with respiratory failure as a consequence of a severe community-acquired pneumonia that required central venous access for antibiotics because no peripheral sites could be obtained. Interventions: None. Measurements and Main Results: The initial ultrasound examination of both legs before femoral catheter insertion revealed no sign of venous thrombosis. Ultrasound of the catheterized leg at 48 hrs revealed a small nonocclusive thrombosis, whereas the opposite leg remained normal. At 72 hrs, the catheterized leg had clinical and ultrasonographic evidence of a massive thrombosis. A compartment syndrome defined by pressure measurements soon ensued and required emergent surgical release. Conclusions: This case report and a review of the available literature suggest that thrombosis associated with femoral vein catheterization should be considered when clinicians decide where to obtain central venous access when multiple sites are available. This report also suggests the utility of serial ultrasound examinations to define clinically nonapparent thrombosis as an early indicator of a potentially catastrophic complication.

The preoperative screening of potential renal transplant donors has undergone a major evolution with the introduction of computed tomographic angiography. With computed tomographic angiography, the radiologist is able to provide the surgeon with precise and valuable preoperative details of renal arterial and venous anatomy. In addition, computed tomographic angiography provides valuable information regarding the renal parenchyma and adjacent organs. This helps reduce the risks and complications associated with transplant surgery and improves the chances of a successful outcome. Helical computed tomographic angiography is rapidly replacing intravenous urography and conventional angiography as the imaging modality of choice for evaluating renal donors.

Increasingly, helical CT is being used to screen trauma patients for aortic injury. Most aortic injuries visible at CT occur at or near the level of the ligamentum arteriosus; these injuries manifest as mediastinal hematoma, aortic contour deformity, intimal flaps, intraluminal debris, pseudoaneurysm, and pseudocoarctation. In the process of searching for aortic injury, however, the radiologist should not overlook other serious and more common thoracic injuries. Tracheobronchial tears appear at CT and radiography with persistent pneumothorax, subcutaneous emphysema, "fallen lung" sign, and malposition of endotracheal tube. The ruptured diaphragm, which tears more often on the left, appears asymmetric, irregular, or discontinuous, with herniation of bowel or viscera into the chest. In esophageal rupture, CT and radiography demonstrate left pneumothorax, pneumomediastinum, subcutaneous emphysema, and pleural effusion and atelectasis on the left. CT is better than trauma radiography for depicting fractures of the thoracic vertebral bodies and ribs, as well as for revealing pulmonary contusions and lacerations. CT is also useful for demonstrating unsuspected injuries caused by seat belts. Observation of these injuries should prompt a search for other serious internal organ injuries.