Multiphasic Computed Tomography Research Articles

Clear Cell Renal Cell Carcinoma: Discrimination from Other Renal Cell Carcinoma Subtypes and Oncocytoma at Multiphasic Multidetector CT

To determine whether enhancement at multiphasic multidetector computed tomography (CT) can help differentiate clear cell renal cell carcinoma (RCC) from oncocytoma, papillary RCC, and chromophobe RCC. With institutional review board approval for this HIPAA-compliant retrospective study, the pathology database was queried to derive a cohort of 298 cases of RCC and oncocytoma with preoperative multiphasic multidetector CT with as many as four phases (unenhanced, corticomedullary, nephrographic, and excretory). A total of 170 clear cell RCCs, 57 papillary RCCs, 49 oncocytomas, and 22 chromophobe RCCs were evaluated for multiphasic enhancement and compared by using t tests. Cutoff analysis was performed to determine optimal threshold levels to discriminate among the four groups. Mean enhancement of clear cell RCCs and oncocytomas peaked in the corticomedullary phase; mean enhancement of papillary and chromophobe RCCs peaked in the nephrographic phase. Enhancement of clear cell RCCs was greater than that of oncocytomas in the corticomedullary (125 HU vs 106 HU, P = .045) and excretory (80 HU vs 67 HU, P = .034) phases. Enhancement of clear cell RCCs was greater than that of papillary RCCs in the corticomedullary (125 HU vs 54 HU, P < .001), nephrographic (103 HU vs 64 HU, P < .001), and excretory (80 HU vs 54 HU, P < .001) phases. Enhancement of clear cell RCCs was greater than that of chromophobe RCCs in the corticomedullary (125 HU vs 74 HU, P < .001) and excretory (80 HU vs 60 HU, P = .008) phases. Thresholding of enhancement helped to discriminate clear cell RCC from oncocytoma, papillary RCC, and chromophobe RCC with accuracies of 77% (83 of 108 cases), 85% (101 of 119 cases), and 84% (81 of 97 cases). Enhancement at multiphasic multidetector CT, if prospectively validated, may assist in the discrimination of clear cell RCC from oncocytoma, papillary RCC, and chromophobe RCC.

Multiphasic contrast-enhanced CT and MRI findings of adult mesoblastic nephroma: A report of two cases

Mesoblastic nephroma (MN) presenting in an adult is extremely rare. The computed tomography (CT) and magnetic resonance imaging (MRI) features of this tumor in adulthood have not been widely reported. We present two additional cases of adult MN and describe the multiphasic contrast-enhanced CT and MRI findings.

Irreversible Electroporation in Porcine Liver

The objective of this study was to define acute computed tomography (CT) characteristics of ablation zone created by irreversible electroporation (IRE) in porcine liver, with histopathologic correlation. Twenty-three IRE ablation zones were created in 4 Yorkshire pig livers percutaneously under image guidance. A prototype generator was used (Ethicon Endo-surgery, Cincinnati, Ohio). Variable spacing of paired electrodes between 1 and 2.0 cm was used. Contrast-enhanced multiphasic CT scans were obtained. Pigs were killed after 5 to 6 hours for gross pathology sectioning with routine and vital histological stains. Computed tomography images were analyzed using 3-dimensional software, and ablation zone size measured on CT was correlated with pathologically determined size. Nineteen of 19 ablation zones created with up to 1.5-cm spacing showed fusion between individual ablation zones generated by each electrode. Ablation zones were isodense precontrast and hypodense to liver postcontrast, with best delineation in the portal phase. Nine of these had nondistorted circumferential margins on both CT and gross pathology suitable for correlation, and among these, size measurements on CT were closely correlated with pathologically determined ablation zone size. Most importantly, on the delayed venous phase, there is internal enhancement within the ablation zone itself, except for small perielectrode zones that remained hypodense. On histopathology, IRE ablation zones showed preserved microvasculature with congestion of sinusoids, except for small perielectrode zones where coagulative changes were suggested. Portal phase contrast-enhanced CT scans correlate well with liver IRE ablation size and shape on histopathology.

Effectiveness of a breath-hold monitoring system in improving the reproducibility of different breath-hold positions in multiphasic CT imaging

This study tests whether the utilization of an electronic breath-hold monitoring device improves breath-hold reproducibility during computed tomographic (CT) scanning. Two cohorts of 40 patients underwent dual-phase abdominal CT scans, either with a breath-hold monitoring device or with the standard breath-holding technique. Two blinded readers measured the differences in diaphragmatic position between phases. There was no statistical difference in diaphragmatic position (P=.14) between the monitored (8.5±11.5 mm) and control (5.6±5.2 mm) cohorts. Ten percent of patients from the monitored cohort had greater than 20 mm of deviation, versus 0%–2.5% for the control cohort. Reproduction of breath-holding position remains challenging, even with a monitoring system.

Autoimmune pancreatitis: Assessment of the enhanced duct sign on multiphase contrast-enhanced computed tomography

PurposeTo assess the usefulness of the computed tomography (CT) finding of main pancreatic duct (MPD) wall enhancement, termed the “enhanced duct sign”, for diagnosis of autoimmune pancreatitis (AIP) in comparison with diagnosis of pancreatic carcinoma and chronic pancreatitis. Materials and methodsTwo radiologists independently evaluated the presence or absence of the enhanced duct sign on multiphase contrast-enhanced CT in patients with AIP (n=55), pancreatic carcinoma (n=50), and chronic pancreatitis (n=50). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of AIP were calculated. In patients demonstrating the enhanced duct sign, additional findings were evaluated by consensus. ResultsThe enhanced duct sign was more frequently observed in patients with AIP (37/55, 67%) than in patients with pancreatic carcinoma (5/50, 10%) or chronic pancreatitis (0/50, 0%) (P<0.05). The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the finding were 0.67, 0.95, 0.85, 0.88, and 0.84, respectively. In AIP, the lumen within the enhanced duct was completely or partially invisible in 29 of 37 (78%) patients, and the enhanced duct was observed within the affected pancreatic parenchyma in 35 of 37 (95%) patients. In pancreatic carcinoma, the lumen within the enhanced duct was visible in all patients (5/5, 100%), and the enhanced duct was observed downstream of the tumor (5/5, 100%). ConclusionThe enhanced duct sign is highly specific of AIP.

CT imaging of primary pleuropulmonary synovial sarcoma

To evaluate the computed tomography (CT) imaging findings of primary pleuropulmonary synovial sarcoma. Five cases of synovial sarcoma confirmed by histopathology and cytogenetic study were retrospectively analysed. All patients had undergone chest radiography and unenhanced and contrast-enhanced CT examinations, and three had also undergone multiphase CT enhancement examinations. Image characteristics, including shape, size, margin, and attenuation of each lesion before and after contrast enhancement, were analysed. The chest radiographs of the five patients showed well-defined or partly well-defined masses, which were homogeneous and without associated calcification or lymphadenopathy. Pneumothorax was present in one patient. The unenhanced CT images showed well-defined, heterogeneous masses with patchy low density in all five patients. The contrast-enhanced CT images showed heterogeneous enhancement in all cases, three of which demonstrated cystic and necrotic areas. The tumour showed no prolonged or delayed enhancement in three cases using multiphase CT. There were small pleural effusions in four cases. No calcification was observed in any of the cases. There was no evidence of hilar or mediastinal lymphadenopathy. In these five patients, primary pleuropulmonary synovial sarcoma presented as a well-defined mass with patchy low density and heterogeneous enhancement, with no evidence of regional lymphadenopathy. It should be included in the differential diagnosis of regional tumours.

Imaging of hepatocellular carcinoma: diagnosis, staging and treatment monitoring

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Imaging is important for establishing a diagnosis of HCC. Several imaging modalities including ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET) and angiography are used in evaluating patients with chronic liver disease and suspected HCC. CT, MRI and contrast-enhanced US have replaced biopsy for diagnosis of HCC. Dynamic multiphase contrast-enhanced CT or MRI is the current standard for imaging diagnosis of HCC. Functional imaging techniques such as perfusion CT and diffusion-weighted MRI provide additional information about tumor angiogenesis that may be useful for treatment. Techniques evaluating tissue mechanical properties such as magnetic resonance elastography, and acoustic radiation force impulse imaging are being explored for characterizing liver lesions. The role of PET in the evaluation of HCC is evolving with promise seen especially with the use of a hepatocyte-specific PET tracer. Imaging is also critical for assessment of treatment response and detection of recurrence following locoregional treatment. Knowledge of the post-treatment appearance of HCC is essential for correct interpretation. This review article provides an overview of the role of imaging in the diagnosis, staging and post-treatment follow-up of HCC.

Noninvasive diagnosis of hepatocellular carcinoma

Noninvasive diagnosis of hepatocellular carcinoma

Fatal mediastinal biopsy: How interventional radiology saves the day

This was a case of a 35-year-old man with mediastinal mass requiring computed tomography (CT)-guided biopsy for tissue diagnosis. A posterior approach with an 18-gauge biopsy needle was used to obtain tissue sample. Post biopsy, patient condition deteriorated and multiphase CT study detected active bleeding in arterial phase at the biopsy site with massive hemothorax. Subsequent angiography showed arterial bleeder arising from the apical branch of the right pulmonary artery. Selective endovascular embolization with NBCA (n-Butyl cyanoacrylate) was successful. Patient survived the complication. The case highlighted a rare complication in a common radiology procedure and the value of the interventional radiology unit in avoiding a fatal outcome.

Integration of 64-Detector Lower Extremity CT Angiography into Whole-Body Trauma Imaging: Feasibility and Early Experience

To evaluate the image quality and clinical utility of a polytrauma computed tomographic (CT) protocol that integrates lower extremity CT angiography into multiphasic whole-body trauma CT by utilizing 64-detector CT and a single contrast material bolus. This retrospective study was institutional review board approved and HIPAA compliant. Informed consent was waived. All patients who underwent CT angiography of the lower extremities integrated with multiphasic torso CT for trauma between May 2005 and September 2009 were included. Two hundred eighty-four patients met the inclusion criteria. The mechanism of trauma was blunt injury in 228 (80.3%) of 284 patients and penetrating in 56 (19.7%) of 284 patients. CT angiography encompassed the joints proximal and distal to the injured region, with scan delay fixed at 25 seconds. Two radiologists retrospectively reviewed all the extremity CT angiograms, noting the presence of vascular injury, and measured the attenuation in the lower extremity arteries. Arterial attenuation, in Hounsfield units, was measured at multiple vascular divisions, and CT angiographic results were compared with clinical outcome, and if available, repeat lower extremity CT angiographic, conventional angiographic, or surgical findings. Sensitivity and specificity with 95% confidence intervals were calculated. Sixty-three arterial injuries were identified in 44 (15.5%) of 284 patients as follows: occlusion (n = 37), narrowing (n = 9), active extravasation (n = 14), pseudoaneurysm (n= 2), and arteriovenous fistula (n = 1). Three patients underwent conventional angiography after CT angiography. Seven patients underwent surgical therapy with all CT angiographic findings confirmed. There were no injuries subsequently identified in the subgroup with a negative result at CT angiography. Of the 864 vascular divisions in which attenuation was measured, 69 (8%) of 864 had a mean attenuation less than 150 HU. Integration of lower extremity CT angiography into multiphasic whole-body trauma imaging is feasible, helps detect clinically relevant vascular injuries, and results in diagnostic image quality in the majority of patients.

Contrast-Enhanced Multiphasic Computed Tomography for Identifying Life-Threatening Mesenteric Hemorrhage and Transmural Bowel Injuries

Active mesenteric hemorrhage and bowel perforation after blunt abdominal trauma warrant immediate surgical intervention. We investigate whether findings on multiphasic computed tomography (CT) can identify life-threatening mesenteric hemorrhage and bowel injuries. Within 1-year period, 106 patients underwent multiphasic CT for evaluation of blunt abdominal injuries. Images obtained at arterial phase, portal phase, and equilibrium phase were retrospectively reviewed with special focus on mesentery and bowel injuries. We compared the recorded findings with surgically proven active mesenteric hemorrhage and transmural bowel injuries. The diagnostic values and positive likelihood ratios of individual CT signs were calculated. Mesenteric contrast extravasation had 73.5 positive likelihood ratio and 75% sensitivity for active mesenteric hemorrhage. Hemorrhage first appeared at arterial phase and portal phase was active and life threatening, different from a contained hemorrhage appeared only at equilibrium phase. For transmural bowel injuries, positive likelihood ratio of full-thickness bowel wall abnormality and extraluminal air was large at 32.5 and 26.9, respectively. However, increased mesenteric fat density and peritoneal fluid had high negative predictive value at 98.9 and 97.8. Mean radiodensity of peritoneal fluid in transmural bowel injuries was significantly lower (30 vs. 44 Hounsfield unit, p = 0.008). Multiphasic CT is accurate in identifying life-threatening mesenteric hemorrhage and transmural bowel injuries.

Prospective Blinded Comparison of Wireless Capsule Endoscopy and Multiphase CT Enterography in Obscure Gastrointestinal Bleeding

To compare the performance of multiphase computed tomographic (CT) enterography with that of capsule endoscopy in a group of patients with obscure gastrointestinal bleeding (OGIB). This prospective HIPAA-compliant study was approved by the institutional review board and the institutional conflict of interest committee. All patients provided written informed consent. Two radiologists, blinded to clinical data and results of capsule endoscopy, interpreted images from CT enterography independently, with discordant interpretations resolved by consensus. Results were compared with those from a reference standard (surgery or endoscopy) and clinical follow-up. Sensitivity and 95% confidence intervals were calculated for each modality. Fifty-eight adult patients, referred for the evaluation of OGIB (occult, 25 patients [43%]; overt, 33 patients [57%]), underwent both tests. A small bowel bleeding source was identified in 16 of the 58 patients (28%). The sensitivity of CT enterography was significantly greater than that of capsule endoscopy (88% [14 of 16 patients] vs 38% [six of 16 patients], respectively; P = .008), largely because it depicted more small bowel masses (100% [nine of nine patients] vs 33% [three of nine patients], respectively; P = .03). No additional small bowel tumors were discovered during the follow-up period (range, 5.6-45.9 months; mean, 16.6 months). In this referral population, the sensitivity of CT enterography for detecting small bowel bleeding sources and small bowel masses was significantly greater than that of capsule endoscopy. On the basis of these findings, the addition of multiphase CT enterography to the routine diagnostic work-up of patients with OGIB should be considered, particularly in patients with negative findings at capsule endoscopy.

Multidetector CT Angiography in Acute Gastrointestinal Bleeding: Why, When, and How

Acute gastrointestinal (GI) bleeding remains an important cause of emergency hospital admissions, with substantial related morbidity and mortality. Bleeding may relate to the upper or lower GI tract, with the dividing anatomic landmark between these two regions being the ligament of Treitz. The widespread availability of endoscopic equipment has had an important effect on the rapid identification and treatment of the bleeding source. However, the choice of upper or lower GI endoscopy is largely dictated by the clinical presentation, which in many cases proves misleading. Furthermore, there remains a large group of patients with negative endoscopic results or failed endoscopy, in whom additional techniques are required to identify the source of GI bleeding. Multidetector computed tomography (CT) with its speed, resolution, multiplanar techniques, and angiographic capabilities allows excellent visualization of both the small and large bowel. Multiphasic multidetector CT allows direct demonstration of bleeding into the bowel and is helpful in the acute setting for visualization of the bleeding source and its characterization. Thus, multidetector CT angiography provides a time-efficient method for directing and planning therapy for patients with acute GI bleeding. The additional information provided by multidetector CT angiography before attempts at therapeutic angiographic procedures leads to faster selective catheterization of bleeding vessels, thereby facilitating embolization. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.313105206/-/DC1.

Is hepatotropic contrast enhanced MR a more effective method in differential diagnosis of hemangioma than multi-phase CT and unenhanced MR?

BackgroundCavernous hemangiomas are the most frequent neoplasms of the liver and in routine clinical practice they often need to be differentiated from malignant tumors and other benign focal lesions. The purpose of this study is to evaluate whether diagnostic accuracy of magnetic resonance imaging (MRI) of hepatic hemangiomas, showing atypical pattern on US, improves with the use of Gd-BOPTA in comparison with contrast-enhanced multi-phase computed tomography (CT).Methods178 consecutive patients with ambiguous hepatic masses showing atypical hyperechoic pattern on grey-scale US, underwent unenhanced and contrast-enhanced multi-phase multi-detector CT and MR (1.5T) with the use of liver-specific contrast medium gadobenate dimeglumine (Gd-BOPTA). After intravenous contrast administration arterial (HAP), venous-portal (PVP), equilibrium phases (EP) both in CT and MR and additionally hepatobiliary phase (HBP) in MR were obtained. 398 lesions have been detected including 99 hemangiomas and 299 other lesions.ResultsIn non-enhanced MDCT examination detection of hemangiomas was characterized by sensitivity of 76%, specificity of 90%, PPV of 71%, NPV of 92% and accuracy of 86%.Non-enhanced MR examination showed sensitivity of 98%, specificity of 99%, PPV of 99%, NPV of 99% and accuracy of 99%.After intravenous administration of contrast medium in MR the mentioned above parameters did not increase significantly.ConclusionGd-BOPTA-enhanced MR in comparison with unenhanced MRI does not improve diagnostic accuracy in discriminating hemangiomas that show non-specific appearance in ultrasound examination. Unenhanced MR as a method of choice should directly follow US in course of diagnostic algorithm in differentiation of hemangiomas from other liver tumors.

Intrahepatic Mass-forming Cholangiocarcinomas: Enhancement Patterns at Multiphasic CT, with Special Emphasis on Arterial Enhancement Pattern—Correlation with Clinicopathologic Findings

To evaluate the imaging features of intrahepatic mass-forming cholangiocarcinomas (IMCCs) at computed tomography (CT), with a special emphasis on the degree and pattern of arterial enhancement, and to determine whether the clinicopathologic features of IMCCs with arterial enhancement differ from those of IMCCs with less arterial enhancement. The institutional review board of Seoul National University Hospital approved this retrospective study, and informed patient consent was waived. Sixty-four patients with 70 pathologically confirmed IMCCs after surgical resection underwent multiphasic CT-unenhanced, hepatic arterial phase (HAP), portal venous phase, and/or equilibrium phase imaging. CT images were retrospectively evaluated for tumor morphology and enhancement features. Patients were placed into typical or atypical enhancement groups according to the presence of enhancement in the largest volume (>50%) of the tumors during the HAP. Imaging features of IMCCs were correlated with pathologic features. The typical and atypical enhancement groups were compared with respect to disease-free survival and overall survival. Survival rates were calculated by using the Kaplan-Meier method, and differences in survival were compared by using the log-rank test. A Cox proportional hazards model was used for multivariate survival analysis. Fifty (71%) of 70 IMCCs showed typical arterial enhancement, and 20 (29%) showed atypical enhancement. The mean diameter of atypical IMCCs was significantly smaller than that of typical IMCCs (P = .001). Chronic liver disease was more frequent in the group with atypical lesions (P = .021). During the HAP, the prevalent enhancement pattern in this group was a mixed pattern of peripheral rim and internal heterogeneous enhancement. At pathologic evaluation, atypically enhancing IMCCs showed less central stroma and necrosis and larger cellular areas and more frequently had a cholangiolocellular component than typically enhancing IMCCs. Arterial enhancement of IMCCs was found to be an independent prognostic factor for longer disease-free survival. Arterially enhancing IMCCs were not rare; thus, enhancement pattern analysis of arterially enhancing IMCCs will be helpful in differentiating them from hepatocellular carcinomas. In addition, arterial enhancement of IMCCs appears to correlate with disease-free survival.

Small (≤20 mm) Pancreatic Adenocarcinomas: Analysis of Enhancement Patterns and Secondary Signs with Multiphasic Multidetector CT

To evaluate the enhancement patterns, prevalence of secondary signs, and histopathologic features of 20-mm-diameter or smaller pancreatic cancers seen on multiphasic multidetector computed tomographic (CT) images. This retrospective study was approved by the institutional review board; the requirement for informed consent was waived. From January 2002 through September 2009, the authors reviewed the clinical and imaging data of 130 consecutive patients (76 men, 54 women; mean age, 64.1 years; age range, 28-82 years) who had surgically proven 30-mm-diameter or smaller pancreatic cancers and underwent preoperative multidetector CT and 33 consecutive patients (17 men, 16 women; mean age, 65.1 years; age range, 48-84 years) who had histopathologically proven pancreatic cancer and underwent incidental multidetector CT before the diagnosis was rendered. Only pancreatic phase CT was performed in two patients, and only hepatic venous phase CT was performed in nine patients. Two radiologists in consensus classified the tumor attenuation as hyper-, iso-, or hypoattenuation during the pancreatic and hepatic venous phases. Accompanying secondary signs, temporal changes in tumor attenuation, and histopathologic findings also were analyzed. The Fisher exact test, χ(2) test, generalized estimating equation, and Student t test were used to compare the variables. Seventy tumors were 20 mm or smaller, and 93 were 21-30 mm. Isoattenuating pancreatic cancers were more commonly observed among the 20-mm or smaller tumors (16 of 59, 27%) than among the 21-30-mm tumors (12 of 93, 13%) (P = .033). They were also more common among well-differentiated tumors (seven of 12, 58%) than among moderately differentiated (20 of 124, 16%) and poorly differentiated (one of 10, 10%) tumors (P = .001). The prevalence of secondary signs differed significantly according to tumor size (53 [76%] of 70 ≤20-mm tumors vs 92 [99%] of 93 21-30-mm tumors) (P < .001). The prevalence of secondary signs was high among isoattenuating pancreatic cancers (14 [88%] of 16 ≤20-mm tumors vs all 12 [100%] 21-30-mm tumors). Most of the isoattenuating tumors seen at prediagnostic CT were hypoattenuating after 6 months (100% [four of four] during pancreatic phase, 71% [five of seven] during hepatic venous phase). The prevalence of isoattenuating pancreatic cancers differed significantly according to tumor size and cellular differentiation. Most small isoattenuating pancreatic cancers showed secondary signs. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101133/-/DC1.

Distinguishing benign from malignant parotid gland tumours: low-dose multi-phasic CT protocol with 5-minute delay

ObjectivesTo explore the percentage enhancement wash-out ratio (PEW) and relative PEW (RPEW) of low-dose multi-phasic computed tomography (CT) in distinguishing benign from malignant parotid gland tumours.MethodsThis study was approved by the ethics committee, and informed patient consent was obtained. 51 patients with parotid tumours proven by histopathology received CT, including 18 with pleomorphic adenomas, 14 with Warthin’s tumours and 19 with malignant tumours. Size and attenuation of parotid tumours were measured. Compared with 5-min attenuation, the 30-s and 90-s PEW (PEW30, PEW90) and RPEW (RPEW30, RPEW90) were calculated.ResultsThere was a significant difference in PEW30, RPEW30, PEW90 and RPEW90 in the parotid neoplasms groups (P < 0.01), and statistical significance existed simultaneously in pleomorphic adenomas vs malignant tumours and Warthin’s tumours vs malignant tumours according to SNK-q test. The optimal diagnosis results of malignancy with 100% specificity (32/32) was obtained by using a combination of the following criteria: −70% > PEW30 < 36%, −30% > PEW30 < 19%, PEW90 > 12%, and the sensitivity (74%) for diagnosis of malignancy was yield.ConclusionsWash-out ratio may assist in differentiating the benign from malignant parotid gland tumours. Combining the percentage of enhanced wash-out ratios of CT protocols can yield diagnostic results for malignancy.

Multi-phase post-mortem CT angiography: development of a standardized protocol

The objective of this work was to develop an easily applicable technique and a standardized protocol for high-quality post-mortem angiography. This protocol should (1) increase the radiological interpretation by decreasing artifacts due to the perfusion and by reaching a complete filling of the vascular system and (2) ease and standardize the execution of the examination. To this aim, 45 human corpses were investigated by post-mortem computed tomography (CT) angiography using different perfusion protocols, a modified heart-lung machine and a new contrast agent mixture, specifically developed for post-mortem investigations. The quality of the CT angiographies was evaluated radiologically by observing the filling of the vascular system and assessing the interpretability of the resulting images and by comparing radiological diagnoses to conventional autopsy conclusions. Post-mortem angiography yielded satisfactory results provided that the volumes of the injected contrast agent mixture were high enough to completely fill the vascular system. In order to avoid artifacts due to the post-mortem perfusion, a minimum of three angiographic phases and one native scan had to be performed. These findings were taken into account to develop a protocol for quality post-mortem CT angiography that minimizes the risk of radiological misinterpretation. The proposed protocol is easy applicable in a standardized way and yields high-quality radiologically interpretable visualization of the vascular system in post-mortem investigations.

Intraindividual Comparison of Gadoxetate Disodium–enhanced MR Imaging and 64-Section Multidetector CT in the Detection of Hepatocellular Carcinoma in Patients with Cirrhosis

To prospectively compare gadoxetate disodium-enhanced magnetic resonance (MR) imaging with multiphasic 64-section multidetector computed tomography (CT) in the detection of hepatocellular carcinoma (HCC) in patients with cirrhosis. Institutional review board approval and informed patient consent were obtained for this prospective study. Fifty-eight patients (39 men, 19 women; mean age, 63 years; age range, 35-84 years) underwent gadoxetate disodium-enhanced MR imaging and multiphasic 64-section multidetector CT. The imaging examinations were performed within 30 days of each other. The two sets of images were qualitatively analyzed in random order by three independent readers in a blinded and retrospective fashion. Using strict diagnostic criteria for HCC, readers classified all detected lesions with use of a four-point confidence scale. The reference standard was a combination of pathologic proof, conclusive imaging findings, and substantial tumor growth at follow-up CT or MR imaging (range of follow-up, 90-370 days). The diagnostic accuracy, sensitivity, and positive predictive value were compared between the two image sets. Interreader variability was assessed. The accuracy of each imaging method was determined by using an adjusted modified chi(2) test. Eighty-seven HCCs (mean size +/- standard deviation, 1.8 cm +/- 1.5; range, 0.3-7.0 cm) were confirmed in 42 of the 58 patients. Regardless of lesion size, the average diagnostic accuracy and sensitivity for all readers were significantly greater with gadoxetate disodium-enhanced MR imaging (average diagnostic accuracy: 0.88, 95% confidence interval [CI]: 0.80, 0.97; average sensitivity: 0.85, 95% CI: 0.74, 0.96) than with multidetector CT (average diagnostic accuracy: 0.74, 95% CI: 0.65, 0.82; average sensitivity: 0.69, 95% CI: 0.59, 0.79) (P < .001 for each). No significant difference in positive predictive value was observed between the two image sets for each reader. Interreader agreement was good to excellent. Compared with multiphasic 64-section multidetector CT, gadoxetate disodium-enhanced MR imaging yields significantly higher diagnostic accuracy and sensitivity in the detection of HCC in patients with cirrhosis.

Percutaneous Cryoablation of Renal Tumors: Patient Selection, Technique, and Postprocedural Imaging

Percutaneous cryoablation of renal tumors requires a number of important steps for success and relies heavily on imaging for treatment planning, intraprocedural guidance and monitoring, detection of untreated tumor, and surveillance for disease progression. Imaging-guided percutaneous cryoablation has several advantages over laparoscopic cryoablation. In particular, computed tomography (CT) and magnetic resonance (MR) imaging allow global evaluation of the ablation zone and an accurate depiction of the treatment margin. Ultrasonography allows real-time guidance of probe placement but cannot help depict ice ball formation as accurately as CT or MR imaging. Multiphasic CT or MR imaging should be performed at structured intervals following ablation. Treated tumors are expected to decrease in size over time, and lesion growth and internal or nodular enhancement are suspicious for tumor recurrence or progression. Complications include probe site pain, hematoma, incomplete ablation, and recurrent tumor. Current limitations of percutaneous cryoablation include the inability to control hemorrhage without intraarterial access and a lack of long-term follow-up data. Nevertheless, percutaneous cryoablation is an effective choice for minimally invasive nephron-sparing treatment of renal tumors.