Delayed imaging in routine CT examinations of the abdomen and pelvis: is it worth the additional cost of radiation and time?

OBJECTIVE: The purpose of this study was to retrospectively assess the potential benefits of delayed phase imaging series in routine CT scans of the abdomen and pelvis. MATERIALS AND METHODS: Routine contrast-enhanced abdominopelvic CT scans of 1000 consecutively examined patients (912 men, 88 women; average age, 60 years; range, 22-94 years) were retrospectively evaluated, and the added benefits of the delayed phase series through the abdomen were recorded for each examination. Examinations performed for indications requiring multiphasic imaging were excluded. Images were reviewed by two fellowship-trained abdominal radiologists, who were blinded to official CT reports. All examinations were performed between July 2008 and February 2010 at a single institution. Radiation doses for both the portal venous and delayed phases, when available, were analyzed to assess the effect of the delayed phase on overall radiation exposure. RESULTS: Forty-two patients (4.2%) had findings that were further characterized or were observed only in the delayed phase. Most were incidental findings that could have been confirmed at noninvasive follow-up imaging, such as sonography or unenhanced CT or MRI. The most common findings were liver hemangioma (n = 12), adrenal adenoma (n = 12), and parapelvic renal cysts (n = 6). The most important finding was detection of a renal mass in one patient (0.1%). The mass was seen only on the delayed phase images but was difficult to appreciate in the portal venous phase. In the other 958 patients (95.8%), delayed imaging was of no benefit. In addition, use of the delayed phase resulted in a mean 59.5% increase in effective radiation dose. CONCLUSION: An additional delayed phase through the abdomen in routine contrast-enhanced CT examinations of the abdomen and pelvis is of low yield, particularly if reliable follow-up imaging to further elucidate uncertain findings is available.

MRI of the epididymis: can the outcome of vasectomy reversal be predicted preoperatively?

OBJECTIVE: The purpose of this study is to describe the MRI findings seen with tubular ectasia of the epididymis and investigate whether MRI may predict vasal/epididymal tubular occlusion before vasectomy reversal. MATERIALS AND METHODS: First, we compared epididymal T1 signal intensity (measured as percentage change relative to ipsilateral testis) in 24 patients with sonographically established tubular ectasia compared with 22 control patients (sonographically normal epididymides). Second, in a subset of patients with tubular ectasia who subsequently underwent surgery to restore fertility (n = 10), we examined the relationship between epididymal T1 signal intensity and surgical outcome. Vasovasostomy (simple vas deferens reanastomosis with high success rate) was possible when viable sperm were detected in the vas deferens intraoperatively. When no sperm were detected, vasal/epididymal tubular occlusion was inferred and vasoepididymostomy (vas deferens to epididymal head anastomosis, a technically challenging procedure with poorer outcome) was performed. RESULTS: In tubular ectasia, we found increased epididymal T1 signal intensity (0-77%) compared with normal epididymides (-27 to 20%) (p < 0.0001). In patients with tubular ectasia who underwent surgery (n = 10), we found higher T1 epididymal signal intensity in cases of vasal/epididymal occlusion (0-70%) relative to cases in which vasal/epididymal patency was maintained (0-10%) (p = 0.01). By logistic regression, relative epididymal T1 signal intensity increase above 19.4% corresponded to greater than 90% probability of requiring vasoepididymostomy. CONCLUSION: Increased epididymal T1 signal intensity (likely due to proteinaceous material lodged within the epididymal tubules) at preoperative MRI in patients undergoing vasectomy reversal suggests vasal/epididymal tubular occlusion and requirement for vasoepididymostomy rather than vasovasostomy.

Differentiation of clear from non-clear cell renal cell carcinoma using CT washout formula.

INTRODUCTION: To further elucidate potential patterns of contrast enhancement for renal neoplasm subtypes, we investigated utility of contrast washout formula to differentiate renal tumor histology after multiphase computerized tomography (CT). MATERIALS AND METHODS: Single center retrospective cohort study of 163 patients with multiphase CT for renal masses obtained October 2007 to July 2012. Pathology confirmed clear cell (CC-RCC; n = 92), papillary (Pa-RCC; n = 43), chromophobe (Ch-RCC; n = 6), oncocytoma (OC; n = 11), or angiomyolipoma (AML; n = 11) histology. Two radiologists in consensus and blinded to histology recorded tumor size, morphology, and attenuation measurements in Hounsfield Units (HU). Data were analyzed between subgroups based on histology. Enhancement washout of the tumor was calculated by the formula (Mass nephrographic HU-Mass delayed HU)/(Mass nephrographic HU-Mass non-contrast HU) and used to calculate sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). RESULTS: Tumor size was largest among CC-RCC (p < 0.001). Homogeneous composition was more common among Pa-RCC and Ch-RCC (p < 0.001). Median washout for Ch-RCC (0.27) was significantly different from that of OC (0.54, p = 0.05). Overall 25 (15.3%) of tumors had washout < 0. Tumors with washout value < 0 were Pa-RCC 24/43 (56%), and Ch-RCC 1/6 (14%). Washout value < 0 had a specificity of 99.2% for Pa-RCC and 100% for non-CC-RCC. Washout value ≥ 0 had a sensitivity and NPV of 100% for CC-RCC, OC, and AML. Washout value ≥ 0 had a specificity of 35.2% and a PPV of 66.7% for CC-RCC. CONCLUSIONS: Enhancement washout value < 0 is highly specific for Pa-RCC and non-CC-RCC. Washout value ≥ 0 is highly sensitive for CC-RCC, OC, and AML while there was a significant difference in median washout between OC and Ch-RCC. Further prospective investigation is requisite to confirm these findings.

Magnetic resonance imaging for intratesticular and extratesticular scrotal lesions.

INTRODUCTION: To evaluate magnetic resonance imaging (MRI) utility in intratesticular and extratesticular scrotal diseases. MATERIALS AND METHODS: Two radiologists retrospectively reviewed images of patients who underwent ultrasound followed by MRI, categorizing them as intratesticular or extratesticular and malignant, benign, indeterminate, or inadequate study. For patients who underwent surgical excision, pathologic results were also correlated to the presurgical ultrasound and MRI diagnoses. RESULTS: Of 69 cases, 38 were intratesticular lesions and 31 were extratesticular lesions. MRI and ultrasound diagnoses were discordant in 21 (55.32%) intratesticular and 19 (61.3%) extratesticular lesions. MRI diagnosis was malignant after an indeterminate ultrasound in 0 and 4 (12.9%) intratesticular and extratesticular lesions, respectively. MRI diagnosis was benign after an indeterminate ultrasound in 18 (47.43%) and 14 (45.2%) intratesticular and extratesticular lesions, respectively. A malignant ultrasound diagnosis was reversed to benign MRI diagnosis in one (2.6%) intratesticular and one (3.2%) extratesticular lesion. In no case was a benign lesion on ultrasound read as malignant on MRI in either group. The cohort of patients with intratesticular lesions received a mean clinical and radiographic follow up of 2.49 ± 1.97 and 1.85 ± 1.46 years, respectively. The patients with extratesticular lesions received a mean clinical and radiographic follow up of 1.30 ± 1.08 and 2.00 ± 1.28 years, respectively. In no case did repeat imaging change the diagnosis after initial MRI and ultrasound evaluation. CONCLUSIONS: MRI was effective at characterizing both intratesticular and extratesticular lesions in the majority of cases.

Ureteral intussusception: a case report and literature review.

We present the case of a 64-year-old man with intussusception of the right ureter as a complication of an underlying transitional cell carcinoma. To our knowledge, this is the first case report that illustrates ureteral intussusception by both multidetector computerized tomography and magnetic resonance imaging. Although ureteral intussusceptions are thought to be associated with benign masses, our comprehensive review of the literature demonstrates that almost half of the cases are associated with underlying malignancy.

Recurrent non-surgical pneumoperitoneum due to jejunal diverticulosis.

BACKGROUND: The presence of free intraperitoneal gas usually warrants emergent surgery. In rare instances, however, non-surgical conditions such as jejunal diverticulosis can cause pneumoperitoneum and do not require intervention. OBJECTIVES: The objective of this article is to provide the computed tomography (CT) scan findings of jejunal diverticulosis causing pneumoperitoneum. The article will also discuss other non-surgical causes of spontaneous pneumoperitoneum to increase awareness and avoid unnecessary surgery. CASE REPORT: We describe a case of recurrent pneumoperitoneum due to jejunal diverticulosis in which the patient remained asymptomatic and free of complications with repeated evaluations in the emergency department over the course of 18 months. CONCLUSION: Although spontaneous pneumoperitoneum due to jejunal diverticulosis is a rare finding, when it does occur, this condition must be distinguished from other forms of pneumoperitoneum to avoid unnecessary surgery. CT scan findings of multiple rounded, variably sized jejunal outpouchings filled with oral contrast are helpful in diagnosing jejunal diverticulosis and confirming the decision for conservative management of the patient.

Renovascular involvement of systemic vascular disease: a pictorial review.

Like many solid organs, the kidneys are susceptible to a wide variety of systemic vascular diseases. Comprising a significant subset of these diseases are the vasculitides, broadly encompassing numerous inflammatory conditions of the blood vessels. However, many of these conditions are non-vasculitic and non-inflammatory, and differentiation of these entities is crucial to guide the initiation of proper therapy. These non-vasculitic diseases include coagulopathic conditions leading to vascular complications, hemolysis, and hematogenous processes that can affect multiple organ systems. These systemic diseases can result in both macrovascular and microvascular pathology, involving the arteries, veins, and smaller vessels, and management of these conditions can differ significantly depending upon the underlying pathophysiology. Because the clinical manifestations of these disease processes can be heterogeneous, ranging from renal dysfunction to life-threatening hemorrhage, proper recognition of these entities is essential to help guide clinicians to the correct diagnosis and prevent potentially disastrous complications. Many of these systemic vascular processes can be detected by non-invasive imaging, including computed tomography (CT) and magnetic resonance imaging (MRI), and identification of their characteristic renal manifestations by radiologists is a critical component of patient care. This review covers a variety of these diseases and their imaging manifestations, to aid in their recognition and better equip radiologists to provide vital diagnostic information that can optimize patient care.

Dots, lines, contours, and ends: An image-based review of esophageal pathology.

Esophageal pathologies encountered on fluoroscopic examination may pose a diagnostic challenge to the interpreting Radiologist. Understanding the varied imaging appearances of esophageal pathology requires a thorough understanding of barium esophagography. This article reviews the various fluoroscopic imaging findings of different esophageal pathologies by describing an approach to image interpretation centered on dots, lines, contours, and ends. By utilizing this approach, the Radiologist will be better positioned to reconcile seemingly disparate pathologies into a cogent and succinct differential diagnosis.

MR imaging of scrotal tumors and pseudotumors.

Magnetic resonance (MR) imaging is an important imaging technique in the evaluation of scrotal masses, providing a useful adjunct to ultrasonography (US). Although US is the modality of choice for initial evaluation of scrotal pathologic conditions because of its wide availability, low cost, and high sensitivity for detection of testicular and paratesticular disease processes, US findings may occasionally be inconclusive. MR imaging may provide additional information in these cases, often affecting patient management. This article reviews and illustrates the MR imaging features of solid extratesticular and intratesticular benign and malignant scrotal tumors, as well as nonneoplastic lesions that can mimic neoplasia. Normal scrotal MR anatomic features and optimal MR imaging technique are also presented.

Follicular pancreatitis: A rare pancreatic inflammatory pseudotumor.

Inflammatory pseudotumors imitate neoplasms on imaging but actually represent focal inflammation. We report a case of follicular pancreatitis, which is a recently recognized distinct form of mass-forming focal chronic pancreatitis pathologically characterized by lymphoid infiltration with abundant reactive germinal centers. In our patient, follicular pancreatitis manifested as a pancreatic tail mass that was resected due to imaging findings, which were suggestive of pancreatic malignancy. We performed a literature review of this rare condition and present a summary of reported imaging findings. The most distinguishing feature from pancreatic adenocarcinoma is the enhancement pattern, as follicular pancreatitis enhances more than the surrounding pancreatic parenchyma on delayed post-contrast images which is unusual for pancreatic adenocarcinoma. If this benign diagnosis is suggested on imaging, unnecessary surgery and its potential complications may be avoided.

Fatty liver disease: MR imaging techniques for the detection and quantification of liver steatosis.

Fatty liver disease is the most common cause of chronic liver disease in the United States. Noninvasive detection and quantification of fat is becoming more and more important clinically, due in large part to the growing prevalence of nonalcoholic fatty liver disease. Steatosis, the accumulation of fat-containing vacuoles within hepatocytes, is a key histologic feature of fatty liver disease. Liver biopsy, the current standard of reference for the assessment of steatosis, is invasive, has sampling errors, and is not appropriate in some settings. Several magnetic resonance (MR) imaging-based techniques--including chemical shift imaging, frequency-selective imaging, and MR spectroscopy--are currently in clinical use for the detection and quantification of fat-water admixtures, with each technique having important advantages, disadvantages, and limitations. These techniques permit the breakdown of the net MR signal into fat and water signal components, allowing the quantification of fat in liver tissue, and are increasingly being used in the diagnosis, treatment, and follow-up of fatty liver disease.

CT urography: how to optimize the technique.

PURPOSE: Computed tomography urography (CTU) has emerged as the modality of choice for imaging the urinary tract within the past few decades. It is a powerful tool that enables detailed anatomic evaluation of the urinary tract in order to identify primary urothelial malignancies, benign urinary tract conditions, and associated abdominopelvic pathologies. As such, there have been extensive efforts to optimize CTU protocol. METHODS: This article reviews the published literature on CTU protocol optimization, including contrast bolus timing, dose reduction, reconstruction algorithms, and ancillary practices. CONCLUSION: There have been many advances in CTU techniques, which allow for imaging diagnosis of a wide spectrum of diseases while minimizing radiation dose and maximizing urinary tract distension and opacification.

Renal tumor structured reporting including nephrometry score and beyond: what the urologist and interventional radiologist need to know.

The purpose of this paper is to describe cross-sectional imaging anatomic and morphologic parameters of solid renal tumors that urologists and interventional radiologists need for precise management, review the commonly used terms and descriptors of those parameters, and suggest a comprehensive reporting system for detected masses.

What a difference a delay makes! CT urogram: a pictorial essay.

PURPOSE: The aim of this pictorial essay is to demonstrate several cases where the diagnosis would have been difficult or impossible without the excretory phase image of CT urography. METHODS: A brief discussion of CT urography technique and dose reduction is followed by several cases illustrating the utility of CT urography. RESULTS: CT urography has become the primary imaging modality for evaluation of hematuria, as well as in the staging and surveillance of urinary tract malignancies. CT urography includes a non-contrast phase and contrast-enhanced nephrographic and excretory (delayed) phases. While the three phases add to the diagnostic ability of CT urography, it also adds potential patient radiation dose. Several techniques including automatic exposure control, iterative reconstruction algorithms, higher noise tolerance, and split-bolus have been successfully used to mitigate dose. The excretory phase is timed such that the excreted contrast opacifies the urinary collecting system and allows for greater detection of filling defects or other abnormalities. Sixteen cases illustrating the utility of excretory phase imaging are reviewed. CONCLUSIONS: Excretory phase imaging of CT urography can be an essential tool for detecting and appropriately characterizing urinary tract malignancies, renal papillary and medullary abnormalities, CT radiolucent stones, congenital abnormalities, certain chronic inflammatory conditions, and perinephric collections.

Transient homogeneously enhancing hepatic masses: can size predict benignity?

OBJECTIVE: The purpose of our study was to test the hypothesis that, in noncirrhotic livers, large size predicts benignity of masses that homogeneously hyperenhance on arterial phase CT and then fade to isoattenuation. MATERIALS AND METHODS: All multiphasic CT scans obtained at a cancer center over a 2-year period were reviewed. In consensus, three authors retrospectively identified 227 hepatic masses (> or = 5 mm) in 55 noncirrhotic patients that homogeneously hyperenhanced on arterial phase and then faded to isoattenuation: 107 masses were malignant and 120 were benign; 37 patients had benign and 18 patients had malignant masses. Two analytic approaches were pursued: per lesion and per patient. For the per-lesion analysis, the mean cross-sectional diameter of each mass was calculated and receiver operator characteristics (ROC) were assessed. For the per-patient analysis, the maximum lesion diameter was determined for each subject and logistic regression models were used to predict lesion classification (benign vs malignant) based on per-patient maximum lesion size and additional information. RESULTS: Masses ranged from 5 to 84.5 mm. All 29 masses > or = 22 mm were benign. Size was a statistically significant classifier of benign versus malignant lesions in the per-lesion analysis (p = 0.024, ROC area under the curve) and a significant or trend-level predictor of tumor type in the per-patient analysis (logistic regression p values of the diameter coefficients: 0.01-0.07). CONCLUSION: In noncirrhotic livers, relatively large size is a significant or trend-level predictor for benign tumors. Homogeneously hyperenhancing masses > or = 22 mm that fade to isoattenuation are benign; smaller masses may be malignant.

Imaging of the scrotum.

Ultrasonography is currently the imaging modality of choice when assessing scrotal lesions. Ultrasound findings are sometimes inconclusive, in which case magnetic resonance (MR) imaging might yield additional important information. This article reviews ultrasound and MR imaging features of various intratesticular and extratesticular lesions including acute and nonacute conditions of the scrotum. Nonneoplastic lesions that can mimic scrotal malignancy are discussed. Normal anatomy and imaging techniques are also presented.

Plugoma: CT findings after prosthetic plug inguinal hernia repairs.

BACKGROUND: Unrecognized CT findings of a prosthetic plug used in inguinal hernia repair can lead to incorrect diagnosis or unnecessary workup of a patient. The objective of this study is to review the expected CT findings present in patients with a history of plug repair. STUDY DESIGN: Retrospective cohort study retrieving clinical and image data from a single-institution database. Patients who underwent prosthetic plug hernia repair during a 5-year period at our institution had their records queried for subsequent abdominal CT scans. These CT scans were reviewed by 2 radiologists for findings referable to the hernia repair. RESULTS: Five-hundred and sixty-four consecutive patients underwent prosthetic plug hernia repair during a 5-year period. Fifty-one patients who had had 55 surgical procedures had subsequent CT scans, none in the early postoperative period. Readers identified 100% of the plugs, 68% of which were described as round or oval in shape. All the plugs were in close proximity to the inferior epigastric artery and were of low density on CT images. Surgical scar was identifiable in 87% of patients. Thirty-two patients (63%) had a second CT scan, demonstrating no change in size and location of the plugoma. CONCLUSIONS: A prosthetic mesh plug is easily seen on CT images, typically appearing as a smooth round or oval hypodense mass close to the inferior epigastric artery, deep to a surgical scar, and stable over time. It can usually be distinguished from pathologic findings. It is important that the radiologist be familiar with the patient's surgical history when interpreting these images.

Superparamagnetic iron oxides and low molecular weight gadolinium chelates are synergistic for direct visualization of advanced liver fibrosis.

PURPOSE: To compare the contrast-to-noise ratio (CNR) of advanced liver fibrosis on nonenhanced (NE), gadolinium enhanced (Gd), superparamagnetic iron oxides enhanced (SPIO), and combined contrast-enhanced (CCE) spoiled gradient echoes (SGEs). MATERIALS AND METHODS: This retrospective study assessed 83 consecutive patients with cirrhosis and 10 consecutive patients without fibrosis. All patients had NE, Gd, SPIO, and CCE images at 1.5 T. A total of six breathhold SGE sequences with varying imaging parameters were assessed. MR images were evaluated qualitatively and, in 15 cirrhotics who underwent liver transplantation, compared to gross pathology. CNR of fibrosis to background liver was compared across sequences and contrast enhancement types. RESULTS: In cirrhotic patients, CCE images on all sequences showed fibrosis as a meshwork of high-signal 1-mm to 3-mm thick reticulations surrounding 2-mm to 5-mm low-signal regenerative nodules. Fibrosis was less visible on Gd and SPIO images and was barely visible on NE images. CNR was significantly higher for CCE than for NE, Gd, or SPIO images in eight of nine comparisons (P < 0.0001-0.05). The liver had a homogeneous appearance in subjects without fibrosis. CONCLUSION: CCE imaging depicts advanced liver fibrosis with higher CNR than NE, Gd, or SPIO SGEs.