Myra K. Feldman

Detection of Urolithiasis: Comparison of 100% Tube Exposure Images Reconstructed with Filtered Back Projection and 50% Tube Exposure Images Reconstructed with Sinogram-affirmed Iterative Reconstruction

PURPOSE To compare images acquired with 50% tube exposure with a dual-source computed tomographic (CT) scanner and reconstructed with sinogram-affirmed iterative reconstruction (SAFIRE) with 100% exposure images reconstructed with filtered back projection (FBP) for reader ability to detect stones, reader confidence, and findings outside the urinary tract. MATERIALS AND METHODS In this HIPAA-compliant, institutional review board-approved study, imaging examinations in 99 patients with urolithiasis were assessed. Data from both tubes were reconstructed with FBP; data from the primary tube only were reconstructed with SAFIRE. Seven readers evaluated randomized studies for calculi in nine regions. Reader confidence was scored by using a five-point scale. Ancillary findings were noted. Nonparametric methods for clustered data were used to estimate the area under the receiver operating characteristic curves with 95% confidence intervals to test for noninferiority of 50% exposure with SAFIRE. RESULTS Calculi were found in 113 locations (pyelocalyceal ureter, 86; proximal ureter, seven; midureter, four; distal ureter, 15; bladder, one) and not found in 752 locations. Mean area under the receiver operating characteristic curve for FBP was 0.879 (range, 0.607-0.967) and for SAFIRE, 0.883 (range, 0.646-0.971; 95% confidence interval: -0.025, 0.031). The SAFIRE images were not significantly inferior to FBP images (P = .001). Reader confidence levels for images with stones were similar with FBP and SAFIRE (P = .963). For the 52 patients who had extraurinary findings, readers reported them correctly in 74.4% (271 of 364) and 72.0% (262 of 364) of cases (P = .215) for FBP and SAFIRE, respectively. For the nine patients with potentially important findings per the reference standard, the detection rates were 44% (28 of 63) and 33% (21 of 63, P = .024), respectively. For the 43 patients with unimportant or likely unimportant findings, the false detection rates were 15% (44 of 301) and 14% (43 of 301, P = .756), respectively. CONCLUSION The 50% tube exposure CT images reconstructed with SAFIRE were not inferior to 100% exposure images reconstructed with FBP for diagnosis of urolithiasis, without decreases in reader confidence.

Diagnostic Accuracy of CT Enterography for Active Inflammatory Terminal Ileal Crohn Disease: Comparison of Full-Dose and Half-Dose Images Reconstructed with FBP and Half-Dose Images with SAFIRE

Purpose To compare the diagnostic accuracy and image quality of computed tomographic (CT) enterographic images obtained at half dose and reconstructed with filtered back projection (FBP) and sinogram-affirmed iterative reconstruction (SAFIRE) with those of full-dose CT enterographic images reconstructed with FBP for active inflammatory terminal or neoterminal ileal Crohn disease. Materials and Methods This retrospective study was compliant with HIPAA and approved by the institutional review board. The requirement to obtain informed consent was waived. Ninety subjects (45 with active terminal ileal Crohn disease and 45 without Crohn disease) underwent CT enterography with a dual-source CT unit. The reference standard for confirmation of active Crohn disease was active terminal ileal Crohn disease based on ileocolonoscopy or established Crohn disease and imaging features of active terminal ileal Crohn disease. Data from both tubes were reconstructed with FBP (100% exposure); data from the primary tube (50% exposure) were reconstructed with FBP and SAFIRE strengths 3 and 4, yielding four datasets per CT enterographic examination. The mean volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) at full dose were 13.1 mGy (median, 7.36 mGy) and 15.9 mGy (median, 13.06 mGy), respectively, and those at half dose were 6.55 mGy (median, 3.68 mGy) and 7.95 mGy (median, 6.5 mGy). Images were subjectively evaluated by eight radiologists for quality and diagnostic confidence for Crohn disease. Areas under the receiver operating characteristic curves (AUCs) were estimated, and the multireader, multicase analysis of variance method was used to compare reconstruction methods on the basis of a noninferiority margin of 0.05. Results The mean AUCs with half-dose scans (FBP, 0.908; SAFIRE 3, 0.935; SAFIRE 4, 0.924) were noninferior to the mean AUC with full-dose FBP scans (0.908; P < .003). The proportion of images with inferior quality was significantly higher with all half-dose reconstructions than with full-dose FBP (mean proportion: 0.117 for half-dose FBP, 0.054 for half-dose SAFIRE 3, 0.054 for half-dose SAFIRE 4, and 0.017 for full-dose FBP; P < .001). Conclusion The diagnostic accuracy of half-dose CT enterography with FBP and SAFIRE is statistically noninferior to that of full-dose CT enterography for active inflammatory terminal ileal Crohn disease, despite an inferior subjective image quality. (©) RSNA, 2016 Online supplemental material is available for this article.

Imaging Evaluation of Pancreatic Cancer

Imaging studies are critical for the detection, characterization, initial staging, management, and monitoring of pancreatic cancer cases. Treatment of pancreatic cancer requires a multidisciplinary approach. Ideally, assessing resectablility with imaging and subsequent treatment decisions should be made at a high-volume center of excellence with a multidisciplinary team. This article reviews the major imaging modalities used to evaluate pancreatic neoplasms, with an emphasis on pancreatic imaging protocols. The imaging appearance of solid pancreatic neoplasms and the imaging criteria used to stage and determine resectability for pancreatic ductal adenocarcinoma are described. An approach to standardized radiologic reporting is also reviewed.

Imaging mimics of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma is the most common primary malignancy of the pancreas. The classic imaging features are a hypovascular mass with proximal ductal dilatation. Different pancreatic pathologies can mimic the imaging appearance of carcinoma including other tumors involving the pancreas (pancreatic neuroendocrine tumors, lymphoma, metastasis, and rare tumors like pancreatic acinar cell carcinoma and solid pseudopapillary tumors), inflammatory processes (chronic pancreatitis and autoimmune pancreatitis), and anatomic variants (annular pancreas). Differentiation between these entities can sometimes be challenging due to overlap of imaging features. The purpose of this article is to describe the common entities that can mimic pancreatic cancer on imaging with illustrative examples and to suggest features that can help in differentiation of these entities.

CT and MRI of the Pelvis for Anorectal Disease

Cross-sectional imaging of the pelvis with CT and MRI plays an important role in the clinical evaluation of patients with anorectal disease. The value of these technologies in the evaluation of and surgical planning for patients with anorectal disease continues to grow as the imaging technologies continue to improve. This paper introduces the techniques and terminology needed to understand these images and the anatomy that can be seen. The MRI evaluation of rectal adenocarcinoma and anal cancer is reviewed including T-staging and assessment of nodal disease. The appearances of less common rectal neoplasms are also briefly reviewed. The imaging of anorectal inflammatory and infectious diseases including abscess and fistulous disease is discussed. Finally, the imaging of postoperative complications including the evaluation of ileal pouches is reviewed.

Noninvasive Imaging of the Biliary Tree for the Interventional Radiologist.

Patients with suspected biliary tract disease often pose a diagnostic challenge to the clinician and radiologist. Although advances across all imaging modalities, including ultrasound, computed tomography, and magnetic resonance, have improved our diagnostic accuracy for biliary disease, many of the imaging findings remain nonspecific. Recognition of key imaging findings combined with knowledge and understanding of the clinical context is essential to piecing together a diagnosis and guiding management for patients with biliary disease. Although there is a wide range of biliary pathology, interventional radiologists most commonly play a role in the management of biliary obstruction and leak.

High Flow Priapism on Color Doppler Ultrasound

A 25-year-old male patient presented with a 3-day history of persistent, painless semirigid erection. He had no history of recent trauma, hematological disease or drug use (recreational, psychotropic or oral supplement). On examination the penile shaft was turgid and nontender. Diffuse ecchymosis was noted along the shaft and scrotum. Arterial blood gas analysis from cavernous aspirate showed pH 7.45, pCO2 36.9, pO2 71.8 and HCO3 24.3. Complete blood count and urinalysis were normal. The clinical findings were consistent with arterial, nonischemic (high flow) priapism. Color Doppler ultrasound (CDU), requested to identify the presence of a potentially treatable arterio-lacunar (AL) fistula, showed asymmetric increased arterial flow in the left cavernosal artery. The right cavernosal artery was patent with a peak systolic velocity of 19 cm per second and the left cavernosal artery had elevated peak systolic velocity greater than 120 cm per second. The left cavernosal arterial spectral Doppler also showed spectral broadening and color Doppler revealed a blush in the left mid shaft consistent with an AL fistula (see figure). There was no flow in the left cavernosal artery immediately beyond this blush but collateral flow was present distally. Priapism is a persistent penile erection lasting more than 4 hours unrelated to a sexual stimulus.