Gender Differences in Aortic Neck Morphology in Patients with Abdominal Aortic Aneurysms Undergoing Elective Endovascular Aneurysm Repair.

BACKGROUND: Previous studies have demonstrated that women tend to have adverse aortic neck morphology leading to exclusion of some women from undergoing endovascular aneurysm repair (EVAR). The objective of this study is to investigate differences in aortic neck morphology in men versus women, changes in the neck morphology and sac behavior after EVAR, and investigate how these features may influence outcomes. METHODS: We conducted a retrospective review of elective EVARs (2004-2013). We excluded patients who underwent elective EVAR with no postoperative imaging available and those patients with fenestrated repairs. Using TeraRecon and volumetric analysis, several features were investigated. These included percent thrombus, shape, length, angulation of the neck, and changes in neck and abdominal aortic aneurysm diameter. RESULTS: A total of 146 patients were found to meet inclusion criteria (115 men and 31 women) with similar baseline characteristics. Neck angulation was greater in women (23.9° vs. 13.5°; P < 0.028). The percent thrombus in women was higher than men (35.4% vs. 31%; P < 0.02). Abdominal aneurysm's were smaller in women at 1 year (4.2 cm vs. 5.1 cm; P < 0.002), and secondary interventions were higher in men (11.3% vs. 0%; P < 0.05). Other features such as neck shape, changes in neck diameter, neck length, and percent oversizing of graft where not statistically different between genders. CONCLUSIONS: Gender differences in neck characteristics and changes in neck morphology do not appear to adversely affect EVAR outcomes. Longer follow-up is necessary to further assess whether these findings are clinically durable.

Acute Appendicitis: Use of Clinical and CT Findings for Modeling Hospital Resource Utilization.

OBJECTIVE: The purpose of this study was to retrospectively investigate associations between baseline CT findings in suspected acute appendicitis and subsequent hospital resource utilization. MATERIALS AND METHODS: One hundred thirty-eight patients (76 male and 62 female patients; mean [± SD] age, 40 ± 21 years) who were admitted for suspected acute appendicitis and underwent baseline CT were included. A single radiologist reviewed CT examinations for appendiceal-related findings. Linear and logistic regressions were performed to identify independent predictors of payer and hospital resource utilization. Combined performance of identified independent factors for predicting outcomes was determined. RESULTS: Greater age, lower Charlson comorbidity index (CCI), lesser appendiceal wall thickness, absence of loculated fluid collection, and absence of periappendiceal fluid were significant independent predictors of inpatient surgery (joint sensitivity, 92.7%; specificity, 65.8%). Smaller appendiceal diameter, absence of periappendiceal fluid, and laparoscopic surgery were significant independent predictors of same-day discharge (joint sensitivity, 79.1%; specificity, 64.2%). Greater CCI, greater wall thickness, and presence of periappendiceal fluid were significant independent predictors of repeat abdominopelvic CT (joint sensitivity, 82.5%; specificity, 68.1%). Presence of an appendicolith was the only significant predictor of repeat emergency department visit within 30 days (sensitivity, 61.2%; specificity, 68.8%) and the only significant predictor of repeat inpatient admission within 30 days (sensitivity, 63.6%; specificity, 68.5%). Greater appendiceal diameter and presence of free air were significant predictors of inpatient costs, and predicted costs were as follows: $8047 + ($745 × appendiceal diameter) if free air was absent; and $-39,261 + ($4426 × appendiceal diameter) if free air was present. However, costs were poorly predicted when greater than $45,000. Sex, WBC count, and payer category were not independent predictors, relative to CT findings, of any outcome. CONCLUSION: Admission CT findings serve as independent predictors of hospital resource utilization in suspected acute appendicitis.

Characterization of adrenal lesions at chemical-shift MRI: a direct intraindividual comparison of in- and opposed-phase imaging at 1.5 T and 3 T.

OBJECTIVE. The purpose of this article is to perform an intraindividual comparison between 1.5 T and 3 T chemical-shift MRI in differentiating adrenal adenomas and nonadenomas, including comparison of quantitative thresholds. MATERIALS AND METHODS. In this retrospective study, 37 adrenal lesions in 36 patients (20 men and 16 women; mean [± SD] age, 66.7 ± 12.9 years; 27 benign adenomas in 27 patients; 10 nonadenomas in nine patients) imaged at 1.5 T and 3 T were identified. Two readers qualitatively assessed intralesional signal loss between in- and opposed-phase images. One reader placed ROIs on adrenal lesions, spleen, liver, and muscle. Quantitative measures of signal loss, such as signal intensity (SI) index, adrenal-to-spleen ratio, adrenal-to-liver ratio, and adrenal-to-muscle ratio, were calculated. Qualitative and quantitative measures between field strengths were assessed with McNemar test and ROC analysis, respectively. RESULTS. Accuracy in qualitative adenoma identification (86.5% [32/37] at 1.5 T and 81.1% [30/37] at 3 T for reader 1; 81.1% [30/37] at 1.5 T and 83.8% [31/37] at 3 T for reader 2; both p ≥ 0.180) was equivalent at both field strengths. AUCs were not statistically significantly different between field strengths for quantitative measures: AUCs at 1.5 T versus 3 T were 0.956 versus 0.915 for SI index, 0.963 versus 0.870 for adrenal-to-spleen ratio, 0.935 versus 0.852 for adrenal-to-liver ratio, and 0.948 versus 0.948 for adrenal-to-muscle ratio (all p > 0.11). The optimal threshold for SI index was lower at 3 T (> 7.4%) than at 1.5 T (> 21.6%) but had similar sensitivity (1.5 T, 92.6% [25/27]; 3 T, 88.9% [24/27]) and specificity (1.5 T, 90.0% [9/10]; 3 T, 90.0% [9/10]). CONCLUSION. Chemical-shift imaging has similar diagnostic efficacy for differentiating adrenal adenomas and nonadenomas at 1.5 T and 3 T. However, quantitative measures have different thresholds for this differentiation at 3 T; in particular, the commonly applied SI index is much lower at 3 T.

Transition zone prostate cancer: revisiting the role of multiparametric MRI at 3 T.

OBJECTIVE. The purpose of this study was to retrospectively evaluate the impact of multiparametric prostate MRI, including diffusion-weighted imaging (DWI) performed using different b values as well as dynamic contrast-enhanced MRI (DCE-MRI) on the accuracy, sensitivity, and specificity for transition zone (TZ) tumor detection and localization. MATERIALS AND METHODS. We included 106 prostate cancer patients (mean age [± SD], 62 ± 7 years) who underwent 3-T MRI with a pelvic phased-array coil before radical prostatectomy. Three radiologists independently reviewed cases to record the likelihood of tumor in each of six TZ regions. Scores were initially assigned using T2-weighted imaging alone, reassigned after integration of DWI at b = 1000 s/mm(2) and corresponding apparent diffusion coefficient (ADC) maps, reassigned again after integration of DWI at b = 2000 s/mm(2), and reassigned a final time after integration of DCE-MRI. Generalized estimating equations based on binary logistic regression were used to compare sessions for TZ tumor detection, using prostatectomy findings as reference standard. RESULTS. Of the TZ sextants, 9.7% (62/636) contained tumor. All readers had higher sensitivity for T2-weighted imaging integrated with DWI at b = 1000 s/mm(2) and ADC compared with T2-weighted imaging alone (reader 1, 54.8% vs 33.9%; reader 2, 53.2% vs 22.6%; and reader 3, 50.0% vs 19.4% [p ≤ 0.002]); two readers had further increased sensitivity also incorporating b = 2000 s/mm(2) (reader 1, 74.2% and reader 2, 62.9%; p ≤ 0.011), and one reader had further increased sensitivity also incorporating both b = 2000 s/mm(2) and DCE-MRI (reader 3, 61.3%, p = 0.013). DCE-MRI otherwise did not improve sensitivity (p ≥ 0.054). Other measures were similar across the four sessions (reader 1, specificity 97.4-98.3% and accuracy 91.2-95.9%; reader 2, specificity 95.8-98.4% and accuracy 91.0-92.6%; reader 3, specificity 90.9-96.7% and accuracy 88.1-89.2%). CONCLUSION. DWI assists TZ tumor detection through higher sensitivity, particularly when using a very high b value; DCE-MRI lacks further additional benefit.

A Multidisciplinary Approach to Improving Appropriate Follow-Up Imaging of Ovarian Cysts: A Quality Improvement Initiative.

PURPOSE: Incidental ovarian cysts are frequently detected on imaging. Despite published follow-up consensus statements, there remains variability in radiologist follow-up recommendations and clinician practice patterns. The aim of this study was to evaluate if collaborative ovarian cyst management recommendations and a radiologist decision support tool can improve adherence to follow-up recommendations. METHODS: Gynecologic oncologists and abdominal radiologists convened to develop collaborative institutional recommendations for the management of incidental, asymptomatic simple ovarian cysts detected on ultrasound, CT, and MRI. The recommendations were developed by modifying the published consensus recommendations developed by the Society of Radiologists in Ultrasound on the basis of local practice patterns and the experience of the group members. A less formal process involved the circulation of the published consensus recommendations, followed by suggestions for revisions and subsequent consensus, in similar fashion to the ACR Incidental Findings Committee II. The recommendations were developed by building on the published work of experienced groups to provide the authors' medical community with a set of recommendations that could be endorsed by both the Department of Gynecology and the Department of Radiology to provide supportive guidance to the clinicians who manage incidental ovarian cysts. The recommendations were integrated into a radiologist decision support tool accessible from the dictation software. Nine months after tool launch, institutional review board approval was obtained, and radiology reports mentioning ovarian cysts in the prior 34 months were retrospectively reviewed. For cysts detected on ultrasound, adherence rates to Society of Radiologists in Ultrasound recommendations were calculated for examinations before tool launch and compared with adherence rates to the collaborative institutional recommendations after tool launch. Additionally, electronic medical records were reviewed to determine the follow-up chosen by the clinician. RESULTS: For cysts detected on ultrasound, radiologist adherence to recommendations improved from 50% (98 of 197) to 80% (111 of 139) (P < .05). Overmanagement decreased from 34% (67 of 197) to 10% (14 of 139) (P < .05). A recommendation was considered "overmanaged" if the radiologist recommended follow-up when it was not indicated or if the recommended follow-up time was at a shorter interval than indicated. Clinician adherence to radiologist recommendations showed statistically nonsignificant improvement from 49% (36 of 73) to 57% (27 of 47) (P = .5034). CONCLUSIONS: Management recommendations developed through collaboration with clinicians may help standardize follow-up of ovarian cysts and reduce overutilization.

Subtype differentiation of renal tumors using voxel-based histogram analysis of intravoxel incoherent motion parameters.

OBJECTIVES: The aim of this study was to determine if voxel-based histogram analysis of intravoxel incoherent motion imaging (IVIM) parameters can differentiate various subtypes of renal tumors, including benign and malignant lesions. SUBJECTS AND METHODS: A total of 44 patients with renal tumors who underwent surgery and had histopathology available were included in this Health Insurance Portability and Accountability Act-compliant, institutional review board-approved, single-institution prospective study. In addition to routine renal magnetic resonance imaging examination performed on a 1.5-T system, all patients were imaged with axial diffusion-weighted imaging using 8 b values (range, 0-800 s/mm). A biexponential model was fitted to the diffusion signal data using a segmented algorithm to extract the IVIM parameters perfusion fraction (fp), tissue diffusivity (Dt), and pseudodiffusivity (Dp) for each voxel. Mean and histogram measures of heterogeneity (standard deviation, skewness, and kurtosis) of IVIM parameters were correlated with pathology results of tumor subtype using unequal variance t tests to compare subtypes in terms of each measure. Correction for multiple comparisons was accomplished using the Tukey honestly significant difference procedure. RESULTS: A total of 44 renal tumors including 23 clear cell (ccRCC), 4 papillary (pRCC), 5 chromophobe, and 5 cystic renal cell carcinomas, as well as benign lesions, 4 oncocytomas (Onc) and 3 angiomyolipomas (AMLs), were included in our analysis. Mean IVIM parameters fp and Dt differentiated 8 of 15 pairs of renal tumors. Histogram analysis of IVIM parameters differentiated 9 of 15 subtype pairs. One subtype pair (ccRCC vs pRCC) was differentiated by mean analysis but not by histogram analysis. However, 2 other subtype pairs (AML vs Onc and ccRCC vs Onc) were differentiated by histogram distribution parameters exclusively. The standard deviation of Dt [σ(Dt)] differentiated ccRCC (0.362 ± 0.136 × 10 mm/s) from AML (0.199 ± 0.043 × 10 mm/s) (P = 0.002). Kurtosis of fp separated Onc (2.767 ± 1.299) from AML (-0.325 ± 0.279; P = 0.001), ccRCC (0.612 ± 1.139; P = 0.042), and pRCC (0.308 ± 0.730; P = 0.025). CONCLUSIONS: Intravoxel incoherent motion imaging parameters with inclusion of histogram measures of heterogeneity can help differentiate malignant from benign lesions as well as various subtypes of renal cancers.