The feasibility of dedicated breast PET for the assessment of residual tumor after neoadjuvant chemotherapy.

PURPOSE: To evaluate the utility of ring-type dedicated breast positron emission tomography (dbPET) for the detection of the residual tumor after neoadjuvant chemotherapy (NAC). MATERIALS AND METHODS: This prospective study included 27 women with histologically proven breast cancer over a 37-month period. All patients underwent ring-type dbPET followed by whole-body PET-CT (WBPET) for preoperative tumor evaluation and re-staging after NAC. The maximum standardized uptake value (SUVmax) of the tumor lesion and the degree of confidence for the presence of the residual tumor were compared between pathological complete response (pCR) and non-pCR tumors. The sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) for the detection of a non-pCR tumor were compared between dbPET and WBPET. RESULTS: On dbPET, SUVmax was significantly higher in non-pCR than in pCR tumors (P = 0.030). The sensitivity for the detection of a non-pCR tumor was significantly higher with dbPET than with WBPET (84.2% vs 26.3%, P = 0.001). In the qualitative analysis, the sensitivity for the detection of a non-pCR tumor was also significantly higher with dbPET than with WBPET (57.9% vs 21.1%, P = 0.016). CONCLUSION: The dbPET can provide more sensitive detection of residual tumor after NAC than can WBPET.

Visualization of right adrenal vein: Comparison with three phase dynamic contrast-enhanced CT.

PURPOSE: To evaluate the visualization of the right adrenal vein (RAV) on dynamic contrast-enhanced computed tomography (CT) images in patients with primary aldosteronism. MATERIALS AND METHODS: We evaluated 27 consecutive patients with primary aldosteronism who underwent contrast-enhanced dynamic CT and subsequent adrenal venous sampling. Scan delays were 10-, 20- and 60-s after a bolus-tracking program detected that the threshold of a 100 Hounsfield units (HU) increase in the abdominal aorta had been achieved. RAV visualization for each phase was evaluated by two readers using a four-point scale. The Friedman and McNemar tests were employed to compare the confidence ratings and the RAV visualization rates between the three phase images. RESULTS: The RAV visualization rates were 20.4%, 83.3%, and 63.0%, for the first, second, and third phase, respectively. The RAV visualization rates were 92.6%, 83.3%, 63.0%, and 92.6% for all three phases combined, the first and second phase image combined, the first and third phase image combined, and second and third phase image combined. The combined second and third phase images had the highest RAV visualization rates compared with all other image combinations (P<0.0001). CONCLUSION: RAV visualization was significantly improved by combining the second and third phase images.

Gadoxetic acid-enhanced high temporal-resolution hepatic arterial-phase imaging with view-sharing technique: Impact on the LI-RADS category.

PURPOSE: To evaluate the value of view-sharing multi-hepatic arterial-phase (mHAP) imaging for diagnosis of hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Forty-seven consecutive patients with HCC underwent gadoxetic acid-enhanced magnetic resonance (MR) imaging before angiographic and lipiodol CT. Hepatic arterial-phase images were obtained at 5 consecutive phases with shared central k-space of 25%, followed by portal venous, late (2 and 3min), and hepatobiliary phase imaging. One-hundred-eight HCC nodules (size: 5-88mm, mean size: 18.2mm) confirmed on angiographic CT and lipiodol CT were evaluated for LI-RADS category and compared with single arterial-phase and mHAP findings regarding wash out, capsule, corona enhancement, and image quality. RESULTS: Twenty-four HCCs (22.2%) (size: 6-19mm, mean size: 12.3mm) were categorized as LR-3 based on the single arterial-phase. Capsule appearance (25.9%) and washout (57.4%) were most frequently observed in late phase (2min). Corona enhancement was observed in 73.1% of all HCCs on mHAP. For the 24 HCCs of LR-3, corona enhancement was observed in 75% on mHAP and contributed to upgrade category. No significant difference was found in the frequency of corona enhancement between mHAP and angiographic CT (P=0.11). Image quality was valued as good or excellent in all cases. CONCLUSION: View-sharing mHAP was feasible without compromising image quality and contributed to the improvement in diagnostic confidence for hypervascular HCC in gadoxetic acid-enhance MR imaging.

Improved diagnosis of common bile duct stone with single-shot balanced turbo field-echo sequence in MRCP.

PURPOSE: To evaluate the value of adding single-shot balanced turbo field-echo (b-TFE) sequence to conventional magnetic resonance cholangiopancreatography (MRCP) for the detection of common bile duct (CBD) stone. METHODS: One hundred thirty-seven consecutive patients with suspected CBD stone underwent MRCP including single-shot b-TFE sequence. Twenty-five patients were confirmed with CBD stone by endoscopic retrograde cholangiopancreatography or ultrasonography. Two radiologists reviewed two image protocols: protocol A (conventional MRCP protocol: unenhanced T1-, T2-, and respiratory-triggered three-dimensional fat-suppressed single-shot turbo spin-echo MRCP sequence) and protocol B (protocol A plus single-shot b-TFE sequence). The sensitivity, specificity, positive (PPV) and negative predictive value (NPV), and area under the receiver-operating-characteristic (ROC) curve (AUC) for the detection of CBD stone were compared. RESULTS: The sensitivity (72%) and NPV (94%) were the same between the two protocols. However, protocol B was greater in the specificity (99%) and PPV (94%) than protocol A (92% and 67%, respectively) (P = 0.0078 and 0.031, respectively). The AUC was significantly greater for protocol B (0.93) than for protocol A (0.86) (P = 0.026). CONCLUSIONS: Inclusion of single-shot b-TFE sequence to conventional MRCP significantly improved the specificity and PPV for the detection of CBD stone.

Biliary tract enhancement in gadoxetic acid-enhanced MRI correlates with liver function biomarkers.

PURPOSE: To evaluate the association between gadoxetic-acid-enhanced magnetic resonance (MR) imaging measurements and laboratory and clinical biomarkers of liver function and fibrosis. MATERIALS AND METHODS: One hundred thirty nine consecutive patients with suspected liver disease or liver tumor underwent gadoxetic-acid-enhanced MR imaging. MR imaging measurements during the hepatobiliary phase included biliary tract structure-to-muscle signal intensity ratio (SIR). These measurements were compared with Child-Pugh classification, end-stage liver disease (MELD) score, and aspartate aminotransferase-to-platelet ratio index (APRI). RESULTS: The SIRs of cystic duct and common bile duct were significantly correlated with Child-Pugh classification (P=0.012 for cystic duct and P<0.0001 for common bile duct), MELD score (P=0.0016 and P=0.0033), and APRI (P=0.0022 and P=0.0015). The sensitivity, specificity, and area under the receiver-operating-characteristic curve were: (74%, 88%, 0.86) with the SIR of common bile duct for the detection of patients with Child-Pugh class B or C; (100%, 87%, 0.94) with the SIR of cystic duct for MELD score (>10); (65%, 76%, 0.70) with the SIR of common bile duct for APRI (>1.5). CONCLUSION: Gadoxetic-acid contrast enhancement of cystic duct and common bile duct could be used as biomarkers to assess liver function.

Determination of the least amount of iodine load required for the detection of pancreatic adenocarcinoma at 80-kVp CT.

PURPOSE: To determine the iodine load per body weight (ILPBW) that is minimally required for the detection of pancreatic adenocarcinoma for 80kVp CT imaging. MATERIAL AND METHODS: Institutional review board approval and written informed consent were obtained. Fifty-seven consecutive patients with histopathologically-proven pancreatic adenocarcinoma were assigned to three groups at random according to iodine load (0.5, 0.4, and 0.3gI/kg) and underwent CT at 80kVp. Enhancement of the pancreas and visualization of the tumor were assessed during the pancreatic parenchymal-phase and compared among the three groups. The relationship between the iodine load and tumor conspicuity was also analyzed. RESULTS: The mean CT number of the pancreas (HUpancreas) was higher in the 0.5gI/kg group (158.8HU) than in the 0.4 (121.7HU) and 0.3 (106.6HU) gI/kg groups (P<0.05). Tumor-to-pancreas contrast (HUtumor-to-pancreas) was also higher in 0.5gI/kg group (88.9HU) than in 0.4 (62.2HU) and 0.3 (54.5HU) gI/kg groups (P<0.05). Linear regression between HUpancreas or HUtumor-to-pancreas and ILPBW were expressed as HUpancreas=23.3+263.9×ILPBW (r=0.74, P<0.0001) and HUtumor-to-pancreas=-1.24+174.3×ILPBW (r=0.56, P<0.0001), respectively. The iodine load estimated to achieve an acceptable HUpancreas (>100HU) and HUtumor-to-pancreas (>50HU) were 0.29 and 0.30gI/kg, respectively. CONCLUSION: An iodine load of 0.3gI/kg was the least amount required for the detection of pancreatic adenocarcinoma at 80kVp CT.