Early dark cortical band sign on CT for differentiating clear cell renal cell carcinoma from fat poor angiomyolipoma and detecting peritumoral pseudocapsule.

OBJECTIVES: To retrospectively evaluate whether the early dark cortical band (EDCB) on CT can be a predictor to differentiate clear cell renal cell carcinoma (ccRCC) from fat poor angiomyolipoma (Fp-AML) and to detect peritumoral pseudocapsules in ccRCC. METHODS: The EDCBs, which are comprised of unenhanced thin lines at the tumor-renal cortex border in the corticomedullary phase, on the CT images of 342 patients who underwent partial nephrectomy were evaluated. Independent predictors among the clinical and CT findings for differentiating ccRCC from Fp-AML were identified using multivariate analyses. The diagnostic performance of the EDCB for diagnosing peritumoral pseudocapsule in ccRCC and differentiating ccRCC from Fp-AML was calculated. RESULTS: The EDCB was observed in 157 of 254 (61.8%) ccRCCs, 4 of 31 (12.9%) chromophobe RCCs, 1 of 21 (4.8%) papillary RCCs, 3 of 11 (27.3%) clear cell papillary RCCs, 3 of 8 (37.5%) oncocytomas, and 0 of 17 (0%) Fp-AMLs. There was substantial interobserver agreement for the EDCB (k = 0.719). The EDCB was a significant predictor for differentiating ccRCC from Fp-AML (p < 0.001). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value of the EDCB for differentiating ccRCC from Fp-AML were 61.8%, 100%, 100%, and 14.9%, respectively, and those for detecting pseudocapsule in 236 ccRCCs were 62.3%, 68.8%, 96.5%, and 11.7%, respectively. CONCLUSION: Although diagnostic accuracy of the EDCB for detecting peritumoral pseudocapsule in RCC is inadequate, it can be a predictor for differentiating ccRCC from Fp-AML with high specificity and PPV. KEY POINTS: • The early dark cortical band (EDCB) sign is observed in nearly two-thirds of clear cell renal cell carcinoma (ccRCC) that are treated by partial nephrectomy and have substantial interobserver agreement. • The EDCB is a significant predictor for differentiating ccRCCs from fat poor angiomyolipomas, with a high specificity and positive predictive value. • Diagnostic accuracy of the EDCB for detecting peritumoral pseudocapsule in ccRCC is inadequate, though better than those in the nephrographic and excretory-phase images.

Artifact-robust diffusion-weighted whole-body imaging with background suppression at 3 T using improved turbo spin-echo diffusion-weighted imaging.

OBJECTIVE:: To compare single-shot turbo spin-echo (TSE) diffusion-weighted whole-body imaging with background suppression (DWIBS) and echo-planar imaging (EPI) DWIBS to determine the feasibility of direct-coronal TSE-DWIBS. METHODS:: All measurements were performed using a 3.0 T MRI scanner. In the phantom study, we compared the contrast ratios (CRs) of tumor-mimicking phantom (tumor) to muscle-mimicking phantom (muscle) and water to muscle and the signal-to-noise ratio (SNR) between TSE-DWIBS and EPI-DWIBS. In the volunteer study, 10 healthy volunteers were whole-body scanned with direct-coronal TSE-DWIBS, direct-coronal EPI-DWIBS (corEPI-DWIBS), and transverse EPI-DWIBS (traEPI-DWIBS). Two radiologists assessed the image distortion, uniformity of fat suppression, overall artifacts, and overall image quality in maximum intensity projection (MIP) images from each DWIBS image using a 5-point scale. RESULTS:: In the phantom study, the CR of tumor to muscle was found to be lower for TSE-DWIBS (10.57 ± 0.45) than for EPI-DWIBS (15.38 ± 0.27), and the CR of water to muscle was higher for TSE-DWIBS (9.61 ± 0.66) than for EPI-DWIBS (2.52 ± 0.60). The volunteer study revealed good inter observer agreement between TSE-DWIBS and EPI-DWIBS with respect to image distortion, uniformity of fat suppression, overall artifacts, and overall image quality, with weighted Cohen's κ coefficients of 0.91, 0.74, 0.87, and 0.72, respectively. Qualitative analysis scores for image distortion, uniformity of fat suppression, overall artifacts, and overall image quality were significantly higher for TSE-DWIBS than for corEPI-DWIBS or traEPI-DWIBS (p < 0.05). CONCLUSION:: Direct-coronal TSE-DWIBS is robust against magnetic field inhomogeneity. High-quality images without distortion or fat suppression inhomogeneity were obtained. ADVANCES IN KNOWLEDGE:: Many studies on DWIBS have been previously reported; however, these studies used EPI read-out. To the best of our knowledge, no studies using TSE read-out have been reported. In this study, we examined the feasibility of TSE-DWIBS with lesser artifacts than EPI-DWIBS.

Techniques of adrenal venous sampling in patients with inferior vena cava or renal vein anomalies.

PURPOSE: To review the techniques and technical success rate of adrenal venous sampling (AVS) in patients with inferior vena cava (IVC) or renal vein anomalies. MATERIALS AND METHODS: The techniques and success rate of AVS in 15 patients with anomalies [8 with double IVC (dIVC), 3 with left IVC (ltIVC), 2 with retroaortic left renal vein (LRV), and 2 with circumaortic LRV] underwent AVS was retrospectively reviewed. RESULTS: Among 11 patients with IVC anomalies, the success rates for sampling the right and left adrenal veins (RAV and LAV) were 81.8 and 90.9%, respectively. In dIVC, the LAV was selected using the following four methods: approaching through the right IVC from the right femoral vein, flipping the LAV catheter tip in the LRV (n = 4) or the interiliac-communicating vein (n = 1), or through the ltIVC from the right (n = 1) or left (n = 2) femoral vein. Among the four patients with LRV anomalies, the success rate was 100% for each adrenal vein. CONCLUSION: AVS can be successfully performed in patients with anomalies. The key to technical success is understanding the venous anatomy based on pre-procedural CT images and choosing appropriate methods.

Reduction of Radiation Exposure Using Dynamic Trace Digital Angiography and Spot Fluoroscopy During Adrenal Venous Sampling.

PURPOSE: To compare radiation exposure of adrenal venous sampling (AVS) using dynamic trace digital angiography (DTDA) and spot fluoroscopy with that using conventional methods. MATERIALS AND METHODS: AVS was performed in 11 patients using DTDA and spot fluoroscopy (Group A) and 11 patients using conventional digital subtraction angiography (DSA) with collimation (Group B). Radiation exposure and image quality of adrenal venography using a five-point scale were compared between the groups. RESULTS: The acquisition dose-area product (DAP) using DTDA and fluoro-DAP using spot fluoroscopy in Group A were lower than those using conventional DSA (5.3 ± 3.7 vs. 29.1 ± 20.1 Gy cm2, p < 0.001) and collimation (33.3 ± 22.9 vs. 59.1 ± 35.7 Gy cm2, p = 0.088) in Group B. The total DAP in Group A was significantly lower than that in Group B (38.6 ± 25.9 vs. 88.2 ± 53.6 Gy cm2, p = 0.006). The peak skin dose for patients and operator radiation exposure in Group A were significantly lower than those in Group B (403 ± 340 vs. 771 ± 416 mGy, p = 0.030, and 17.1 ± 14.8 vs. 36.6 ± 21.7 µSv, p = 0.013). The image quality of DTDA (4.4 ± 0.6) was significantly higher than that of digital angiography (3.8 ± 0.9, p = 0.011) and equivalent to that of DSA (4.3 ± 0.8, p = 0.651). CONCLUSIONS: Radiation exposure during AVS can be reduced by approximately half for both patients and operators by using DTDA and spot fluoroscopy without sacrificing image quality.

Successful Adrenal Venous Sampling by Non-experts with Reference to CT Images.

PURPOSE: To establish technical success rates and safety of adrenal venous sampling (AVS) performed by non-experts with reference to CT images. MATERIALS AND METHODS: 104 AVS procedures with adrenocorticotropic hormone stimulation were performed for patients with suspected primary aldosteronism. One of three radiology residents with 2nd, 5th, and 5th grade experience undertook the procedure under the guidance of an experienced, board-certified interventional radiologist with reference to contrast-enhanced CT images obtained in 102 cases. Successful catheterization of the adrenal veins was assessed using three criteria: an adrenal venous cortisol concentration of more than 200 µg/dL (criterion A); an adrenal vein/inferior vena cava cortisol ratio of more than 5:1 (criterion B); and an adrenal vein/inferior vena cava cortisol ratio of more than 10:1 (criterion C). RESULTS: The operators were aware of the anatomy of the left adrenal veins in 102 cases (98 %) and of the right adrenal veins in 99 cases (95 %) prior to the procedure. CT identified the correct position of the right adrenal vein orifice in 82 of 99 cases (83 %). The overall technical success rates for AVS from the right adrenal vein according to criteria A, B, and C, were 96, 96, and 94 %, respectively. Those for the left adrenal vein were 97, 98, and 94 %, respectively. No significant differences in success rates were observed between the operators (p = 0.922-0.984). No major complications, including adrenal vein rupture, were observed. CONCLUSIONS: When CT images are used to guide AVS, the procedure can be performed successfully and safely even by non-experts.

Dual adrenal venous phase contrast-enhanced MDCT for visualization of right adrenal veins in patients with primary aldosteronism.

PURPOSE: To evaluate the frequency of visualization of the right adrenal vein (RAV) on dual adrenal venous phase multi-detector computed tomography (MDCT) in patients with primary aldosteronism. MATERIALS AND METHODS: Images of contrast-enhanced dual adrenal venous phase MDCT (45- and 55-second delays) in 90 patients with primary aldosteronism who underwent adrenal venous sampling were retrospectively evaluated. The degree of RAV visualization on each phase image was evaluated by two radiologists using a five-point scale and RAV visualization rates were estimated. RESULTS: The RAV visualization rates on the first- and second-phase images were 89 % and 91 % by radiologist A, and 93 % and 90 % by radiologist B, respectively. No significant differences in the score of RAV visualization were observed between the first- and second-phase images by the two readers (P = 0.164 and P = 0.06). The kappa values for inter-observer agreement of RAV visualization on the first- and second-phase images were 0.57 and 0.46, respectively. The consensual RAV visualization rates on the first- and second-phase images were 91 % and 92 %, respectively. The overall RAV visualization rate by using both phase images was 98 %. CONCLUSION: Dual adrenal venous phase MDCT can visualize the RAV in almost all patients with primary aldosteronism. KEY POINTS: • Dual adrenal venous phase MDCT images can visualize the right adrenal veins. • The adrenal venous phase lies between the arterial and portal phases. • Anatomical information will contribute to the technical success of adrenal venous sampling.

Fat-poor angiomyolipoma with cyst-like changes mimicking a cystic renal cell carcinoma: a case report.

Angiomyolipoma is a common benign renal tumor. It is typically composed of adipose tissue and hence is easily diagnosed by using imaging methods such as ultrasonography, computed tomography, and magnetic resonance imaging. However, it is difficult to differentiate an atypical angiomyolipoma such as a fat-poor angiomyolipoma from a malignant tumor by using these imaging methods. We report a case of a fat-poor angiomyolipoma with cyst-like changes in a 35-year-old man. The angiomyolipoma was initially suspected to be a cystic renal cell carcinoma according to preoperative imaging studies. A 5-cm cystic tumor with an enhanced septal wall and exophytic formation was present in the middle section of the left kidney. The patient underwent partial nephrectomy. Pathological findings showed necrosis and hematoma in almost the entire lesion, with a small amount of adipose and muscle tissue. Finally, a fat-poor angiomyolipoma was diagnosed.

Early postoperative screening by contrast-enhanced CT and prophylactic embolization of detected pseudoaneurysms prevents delayed hemorrhage after partial nephrectomy.

PURPOSE: To evaluate retrospectively whether prophylactic embolization of pseudoaneurysms detected on early postoperative screening with computed tomography (CT) after partial nephrectomy can prevent delayed hemorrhage. MATERIALS AND METHODS: Between January 2012 and May 2014, early postoperative contrast-enhanced CT was performed 3-5 days after partial nephrectomy in 312 patients (group A); CT was not performed in 65 patients (group B) because of renal insufficiency or contrast medium allergy. If pseudoaneurysms were detected on CT in group A, prophylactic embolization was performed. The frequency of delayed hemorrhage occurring more than 3 days after surgery in group A was compared with group B and with 212 patients (group C) who underwent partial nephrectomy between January 2010 and December 2011 without early postoperative CT. Changes in estimated glomerular filtration rate at discharge were compared among the groups. RESULTS: Prophylactic embolization of pseudoaneurysms was performed in 26 patients (8%) in group A. Frequency of delayed hemorrhage in group A (0.6%) was significantly lower than in groups B (4.6%; P = .038) and C (4.7%; P = .005). No major complications attributable to prophylactic embolization were observed. The decrease in estimated glomerular filtration rate in group A (-2% ± 13%) was smaller than that in group B (-8% ± 13%; P < .001) and not worse than that in group C (-4% ± 14%; P = .108). CONCLUSIONS: Prophylactic embolization of pseudoaneurysms detected on early postoperative CT can prevent delayed hemorrhage after partial nephrectomy, without major complications.

Assessment of cerebrospinal fluid flow patterns using the time-spatial labeling inversion pulse technique with 3T MRI: early clinical experiences.

CSF imaging using the time-spatial labeling inversion pulse (time-SLIP) technique at 3T magnetic resonance imaging (MRI) was performed to assess cerebrospinal fluid (CSF) dynamics. The study population comprised 15 healthy volunteers and five patients with MR findings showing expansive dilation of the third and lateral ventricles suggesting aqueductal stenosis (AS). Signal intensity changes were evaluated in the tag-labeled CSF, untagged brain parenchyma, and untagged CSF of healthy volunteers by changing of black-blood time-inversion pulse (BBTI). CSF flow from the aqueduct to the third ventricle, the aqueduct to the fourth ventricle, and the foramen of Monro to the lateral ventricle was clearly rendered in all healthy volunteers with suitable BBTI. The travel distance of CSF flow as demonstrated by the time-SLIP technique was compared with the distance between the aqueduct and the fourth ventricle. The distance between the foramen of Monro and the lateral ventricle was used to calculate the CSF flow/distance ratio (CD ratio). The CD ratio at each level was significantly reduced in patients suspected to have AS compared to healthy volunteers. CSF flow was not identified at the aqueductal level in most of the patients. Two patients underwent time-SLIP assessments before and after endoscopic third ventriculostomies (ETVs). CSF flow at the ETV site was confirmed in each patient. With the time-SLIP technique, CSF imaging is sensitive enough to detect kinetic changes in CSF flow due to AS and ETV.