Establishing Normal Values for Shear-Wave Elastography of the Renal Cortex in Healthy Adults.

BACKGROUND: Shear-wave elastography of the kidney has emerged as a potential clinical application of this novel imaging tool. However, normal velocity values for shear-wave elastography involving the cortex of healthy kidneys have not been definitively established, and both inter- and intraobserver reliability has yet to be comprehensively evaluated. METHODS: This prospective study involved ultrasound examination of 11 healthy adults. Shear-wave velocity values were obtained at the renal cortex in the longitudinal and transverse planes by both junior (fellow) and senior (attending) radiologists. RESULTS: The mean shear-wave velocity values ranged between 2.82 and 2.9 m/s, which did not vary significantly between observers (junior vs. senior) or method of measurement (longitudinal vs. transverse planes), P = 0.533. However, there was a wide variation for these measurements (0.51-4.99 m/s). Separate analysis of the measurement depth demonstrated no statistically significant association with the shear-wave velocity values, P = 0.477. CONCLUSION: Our results agree with previous publications and help establish normal shear-wave velocity values and their range for the renal cortex in adults.

CT enterography at 100 kVp with iterative reconstruction compared to 120 kVp filtered back projection: evaluation of image quality and radiation dose in the same patients.

PURPOSE: To perform qualitative and quantitative comparison of images in same patients undergoing CT enterography (CTE) with 100 kVp iterative reconstruction and 120 kVp filtered back projection. METHODS: In this retrospective study, 50 consecutive patients who underwent imaging with 100 kVp and iterative reconstruction (100-IR) and had prior imaging with 120 kVp filtered back projection (120-FBP) were included. Subjective image quality parameters were evaluated by two independent and blinded readers, with higher score implying better image quality. We developed a quantitative measure of image sharpness by measuring edge-width of the psoas-fat interface. Image noise was measured as a standard deviation of attenuation measurement in the homogeneous region of the subcutaneous fat. Image sharpness and noise were measured and compared between 100-IR and 120-FBP acquisitions. RESULTS: There was approximately 33% lower radiation dose as estimated by CTDIvol with 100-IR compared to 120-FBP (9.95 vs. 15.0; p < 0.0001). There were no significant differences in overall image quality, bowel wall sharpness, and subjective assessment of noise and artifact between 100-IR and 120-FBP for both readers. Mesenteric vessel clarity score was significantly higher with 100-IR for 1 reader (4.34 vs. 4.04; p = 0.008), but not for the second reader. There was higher image sharpness (1.62 vs. 1.89; p < 0.0001) and higher image noise (14.4 vs. 13.2; p = 0.020) with 100-IR compared to 120-FBP acquisition. CONCLUSIONS: CTE performed at 100 kVp with iterative reconstruction demonstrates dose reduction without significant impact on various measures of image quality when compared to conventional 120 kVp FBP.

Utility of MRI features in differentiation of central renal cell carcinoma and renal pelvic urothelial carcinoma.

OBJECTIVE: The purpose of this article is to evaluate the utility of various morphologic and quantitative MRI features in differentiating central renal cell carcinoma (RCC) from renal pelvic urothelial carcinoma. MATERIALS AND METHODS: Sixty patients (39 men and 21 women; mean [± SD] age, 65 ± 14 years; 48 with central RCC and 12 with renal pelvic urothelial carcinoma) who underwent MRI, including diffusion-weighted imaging (b values, 0, 400, and 800 s/mm(2)) and dynamic contrast-enhanced imaging, before histopathologic confirmation were included. Tumor T2 signal intensity and apparent diffusion coefficients (ADCs) were measured and normalized to muscle and CSF (hereafter referred to as normalized T2 signal and normalized ADC, respectively) and then were compared using receiver operating characteristic analysis. Also, two blinded radiologists independently assessed all tumors for various qualitative features, which were compared with the Fisher exact test and unpaired Student t test. RESULTS: Urothelial carcinoma exhibited significantly lower normalized ADC than did RCC (p = 0.008), but no significant difference was seen in ADC or normalized T2 signal intensity (p = 0.247-0.773). Normalized ADC had the highest area under the curve (0.757); normalized ADC below an optimal threshold of 0.451 was associated with sensitivity of 83% and specificity of 71% for diagnosing urothelial carcinoma. Features that were significantly more prevalent in urothelial carcinoma included global impression of urothelial carcinoma, location centered within the collecting system, collecting system defect, extension to the ureteropelvic junction, preserved renal shape, absence of cystic or necrotic areas, absence of hemorrhage, homogeneous enhancement, and hypovascularity (all p < 0.033). Increased T1 signal intensity suggestive of hemorrhage was significantly more prevalent in RCC (p = 0.02). Interreader agreement for the subjective features ranged from 61.7% to 98.3%. CONCLUSION: In addition to various qualitative MRI parameters, normalized ADC has utility in differentiating central RCC from renal pelvic urothelial carcinoma. Such differentiation may assist decisions regarding possible biopsy and treatment planning.

Prevalence, characteristics, and fate of intrahepatic nontumorous arterioportal shunts on MRI in patients with hepatic steatosis.

OBJECTIVE: To assess the frequency, characteristics, and fate of arterioportal shunts in patients with hepatic steatosis and to compare this to the frequency in patients without liver disease. METHODS: Eighty-four patients with hepatic steatosis but no other known liver disease and who underwent 2 abdominal magnetic resonance imaging (MRI) examinations at least 1 year apart formed one study cohort. Eighty-four subjects without steatosis or other known liver disease and who also underwent 2 MRI examinations at least 1 year apart formed a control group. Two radiologists evaluated the initial study for the presence and characteristics of arterial enhancing foci not visible on other sequences and assessed the fate of these foci on the follow-up study. RESULTS: Of the patients with steatosis, 36.9% (95% confidence interval [CI], 26.6%-48.1%) demonstrated a total of 108 arterial enhancing foci, compared with 20 arterial enhancing foci in 13.1% of controls (95% CI, 6.7%-22.2%). Both the number of subjects with at least one arterial enhancing focus and the mean number per subject were significantly greater in the steatosis cohort (P < 0.001). The arterial enhancing foci were generally small and peripheral in location in both cohorts. On follow-up examination, all lesions disappeared, decreased in size, were stable, or increased slightly in size while remaining inconspicuous on other sequences. CONCLUSION: Findings consistent with arterioportal shunts were observed at an unexpectedly high frequency in the control group but at a significantly greater frequency in the steatosis group. All foci exhibited benign behavior on long-term follow-up. Future studies may assess for clinical implications of this finding in patients with hepatic steatosis.

Determination of age-related changes in structure and function of skin, adipose tissue, and skeletal muscle with computed tomography, magnetic resonance imaging, and positron emission tomography.

In this article, we report quantitative preliminary data obtained from retrospective analysis of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) and combined PET-computed tomography (PET/CT) examinations in subjects ages 3 to 84 years pertaining to changes in the metabolism of skin, subcutaneous adipose tissue, visceral adipose tissue, and skeletal muscle with age, as well as age-related changes in skeletal muscle attenuation. We also propose a new method for identifying hypermetabolic brown fat on FDG-PET. Finally, we present a review of the literature regarding reported age-related structural and functional changes that occur in skin, fat, and skeletal muscle. Using FDG-PET, We evaluated 213 subjects for changes in the metabolism of skin, adipose tissue, and skeletal muscle with aging. Thirty-two separate subjects were chosen to measure maximum standardized uptake value (SUV) of hypermetabolic brown fat on dual-time point PET imaging. Finally, 15 subjects evaluated by PET/CT were selected to measure changes in metabolism and attenuation of skeletal muscle, and changes in metabolism of adipose tissue with aging. We found that skin, fat, and skeletal muscle all demonstrate significant (P < 0.05) increases in SUV with increasing age on PET imaging. Dual-time point PET imaging demonstrates increasing FDG uptake of hypermetabolic brown fat in various regions studied. Finally, our PET/CT studies revealed statistically insignificant (P > 0.05) decreases in SUV of adipose tissue with aging and the opposite trend in skeletal muscles (P > 0.05). Skeletal muscle attenuation in the various regions studied was found to significantly decrease with age (P < 0.05). Our study shows notable trends in metabolism and attenuation of skeletal muscle and metabolism of skin and adipose tissue that occur with normal aging. We hope that the methodologies and data we present here will serve as a useful starting point for those interested in conducting future prospective research on age-related changes in these structures.

Age-related structural and functional changes in the breast: multimodality correlation with digital mammography, computed tomography, magnetic resonance imaging, and positron emission tomography.

Preliminary results generated from digital mammography, computed tomography, magnetic resonance imaging, and (18)F-fluorodeoxyglucose positron emission tomography demonstrate concordant findings of decreasing glandular tissue and decreasing metabolic activity with increasing age. These results are presented in the context of a detailed literature review summarizing age-related changes in the breast, both from the histologic/physiologic and the imaging perspectives. We also discuss potential applications of this approach and emphasize the importance of new advanced imaging technologies to offer high levels of quantitative precision for tissue characterization for research and clinical purposes.

Secondary achalasia and other esophageal motility disorders after laparoscopic Nissen fundoplication for gastroesophageal reflux disease.

OBJECTIVE: The purpose of our investigation was to determine the frequency of secondary achalasia and other esophageal motility disorders revealed on barium studies after laparoscopic Nissen fundoplication and to present the clinical and radiographic findings in these patients. CONCLUSION: Esophageal dysmotility was found in nine (7%) of 138 patients after laparoscopic Nissen fundoplication, including secondary achalasia in three (33%), diffuse esophageal spasm (DES) in two (22%), and a nonspecific esophageal motility disorder in four (44%). Our findings suggest that patients who undergo laparoscopic Nissen fundoplication for gastroesophageal reflux disease are at risk for the development of esophageal motility disorders, including secondary achalasia and DES. Careful evaluation of esophageal motility on postoperative barium studies may help to identify esophageal dysmotility and to differentiate this finding from structural complications of the wrap as a cause of refractory symptoms in these patients.

Unusual migration of fractured ERCP guidewire: A case report.

Endoscopic retrograde cholangiopancreatography (ERCP) routinely uses hydrophilic guidewires to cannulate ducts and traverse stenoses. Fracture of these guidewires have been reported, however, migration of these fractured fragments is an extremely rare occurrence that has yet to be reported in the literature. We present a case of a fractured ERCP guidewire with extensive migration in the retroperitoneal and lower extremity soft tissues and vasculature with radiologic correlation across multiple modalities-MRI, CT, and radiographs-as well as pathologic correlation. This case illustrates a rare but serious complication of ERCP and demonstrates the imaging findings associated with it.

Association between changes in suspicious prostate lesions on serial MRI examinations and follow-up biopsy results.

We assessed changes in prostate lesions on serial magnetic resonance imaging (MRI) examinations in predicting biopsy results. Fifty-five men undergoing two prostate MRI examinations ≥6 months apart, followed by targeted biopsy, were included. Two radiologists assessed dominant lesions for an increase in size or suspicion score. Progression on MRI had lower sensitivity (23.5%-35.3%) and higher specificity (76.2%-90.5%) than prostate-specific antigen (PSA) velocity (sensitivity 70.6%, specificity 52.4%) for predicting positive biopsy. Highest accuracy was achieved by PSA velocity (63.6%) for positive biopsy, and by MRI (65.5%-72.7%) for Gleason >6 tumor. Findings support lesion progression on MRI serving as a basis for performing subsequent targeted biopsy.

Impact of size of region-of-interest on differentiation of renal cell carcinoma and renal cysts on multi-phase CT: preliminary findings.

INTRODUCTION: To assess impact of size of regions-of-interest (ROI) on differentiation of RCC and renal cysts using multi-phase CT, with focus on differentiating papillary RCC (pRCC) and cysts given known hypovascularity of pRCC. METHODS: 99 renal lesions (23 pRCC, 47 clear-cell RCC, 7 chromophobe RCC, 22 cysts) underwent multi-phase CT. Subjective presence of visual enhancement was recorded for each lesion. Whole-lesion (WL) ROIs, and small (≤ 5 mm(2)), medium (average size of small and large ROIs), and large (half of lesion diameter) peripherally located partial-lesion (PL) ROIs, were placed on non-contrast and nephrographic phases. Impact of ROI size in separating cysts from all RCC and from pRCC based on increased attenuation between phases was assessed using ROC analysis. RESULTS: Visual enhancement was perceived in 96% of ccRCC, 61% of pRCC, and 9% of cysts. AUCs for separating all RCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 91%, 96%, 91% and 93%, and among lesions without visible enhancement were 60%, 79%, 67% and 67%. AUCs for separating pRCC and cysts for WL-ROI and small, medium, and large PL-ROIs were 78%, 92%, 82% and 84%, and among lesions without visible enhancement were 64%, 88%, 69% and 69%. CONCLUSION: Small PL-ROIs had higher accuracy than WL-ROI or other PL-ROIs in separating RCC from cysts, with greater impact in differentiating pRCC from cysts and differentiating lesions without visible enhancement. Thus, when evaluating renal lesions using multi-phase CT, we suggest placing small peripheral ROIs for highest accuracy in distinguishing renal malignancy and benign cysts.

Renal masses measuring under 2 cm: pathologic outcomes and associations with MRI features.

PURPOSE: To evaluate pathologic outcomes and associations with MRI features in small renal masses measuring up to 20mm METHODS: 86 patients (61 ± 13 years; 45 M/41F) with 92 renal masses measuring up to 20mm that underwent MRI prior to tissue diagnosis were included. Two radiologists independently evaluated all masses for microscopic lipid, hemorrhage, T2-hyperintensity, T2-homogeneity, cystic/necrotic areas, hypervascularity, enhancement homogeneity, circumscribed margins, and predominantly exophytic location. These MRI features, as well as patient age, gender, and history of RCC, were compared with pathologic findings using Fisher's exact test, unpaired t-test, and multivariate logistic regression. RESULTS: 26.1% (24/92) of masses under 2 cm were benign, only 32.6% (30/92) were clear-cell RCC, and only 7.6% (7/92) were high-grade. Among 16 masses measuring up to 1cm, only 12.5% (2/16) were clear-cell RCC, and none was high-grade. Within the entire cohort, no MRI or clinical feature showed a significant difference between benign and malignant lesions (p ≥ 0.053). However, for both readers, clear-cell RCC exhibited a significantly higher frequency of T2-hyperintensity, cystic/necrotic areas, and hypervascularity, and a significantly lower frequency of hemorrhage, T2-homogeneity, and enhancement homogeneity (p<0.001-0.036). Hypervascularity was a significant independent predictor of clear-cell RCC for both readers (p=0.002-0.007), as was T2-hyperintensity for reader 2 (p=0.007). CONCLUSION: A substantial fraction of small renal masses were benign, and when malignant, largely exhibited indolent pathologic characteristics, particularly when measuring under 1cm Although small benign and malignant masses could not be differentiated on MRI, hypervascularity showed a significant independent association with clear-cell RCC in comparison with other lesions.

Complex cystic renal masses: comparison of cyst complexity and Bosniak classification between 1.5 T and 3 T MRI.

PURPOSE: To retrospectively compare perceived complexity and Bosniak cyst classification of cystic renal lesions between 1.5 T and 3 T MRI. METHODS: 33 cystic renal lesions in 26 patients that underwent contrast-enhanced MRI at both 1.5 T and 3 T within a 12 month span were included. Two radiologists (R1, R2) independently assessed lesions, unaware of field strength, in terms of number of septations, septal thickening, mural thickening, presence of mural nodule, and Bosniak cyst category. Scores were compared between field strengths for each lesion. RESULTS: R1 observed increases in septal number, septal thickening, mural thickening, and presence of mural nodule at 3T in 8, 7, 4, and 2 lesions, and at 1.5 T in 3, 3, 2, and 0 lesions, respectively; R2 observed increases in septal number, septal thickening, mural thickening, and presence of mural nodule at 3T in 3, 4, 3, and 0 lesions, and at 1.5 T in 2, 0, 0, and 0 lesions, respectively. R1 provided higher Bosniak category at 3T in 9 cases and at 1.5 T in 4 cases; R2 provided higher Bosniak category at 3T in 4 cases and at 1.5 T in 0 cases. Higher scores at 3T than 1.5 T were associated with differences in advised clinical management in 7/9 cases for R1 and 4/4 cases for R2. CONCLUSION: There was an overall tendency for both readers to upgrade cyst complexity and Bosniak cyst category at 3T than 1.5 T, which impacted advised management. Thus, we suggest that serial MRI evaluation of cystic renal lesions be performed at constant field strength.