Efficacy of Computed Tomography-Based Evaluation of Myocardial Extracellular Volume Combined With Red Flags for Early Screening of Concealed Cardiac Amyloidosis in Patients With Atrial Fibrillation.

BACKGROUND: The prevalence of transthyretin amyloid cardiomyopathy (ATTR-CM) in atrial fibrillation (AF) patients remains unclear. We explored the efficacy of computed tomography-based myocardial extracellular volume (CT-ECV) combined with red flags for the early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.Methods and Results: Patients referred for AF ablation at Oita University Hospital were prescreened using the red-flag signs defined by echocardiographic or electrocardiographic findings, medical history, symptoms, and blood biochemical findings. Myocardial CT-ECV was quantified in red flag-positive patients using routine pre-AF ablation planning cardiac CT with the addition of delayed-phase cardiac CT scans. Patients with high (>35%) ECV were evaluated using technetium pyrophosphate (99 mTc-PYP) scintigraphy. A cardiac biopsy was performed during the planned AF ablation procedure if 99 mTc-PYP scintigraphy was positive. Between June 2022 and June 2023, 342 patients were referred for AF ablation. Sixty-seven (19.6%) patients had at least one of the red-flag signs. Myocardial CT-ECV was evaluated in 57 patients because of contraindications to contrast media, revealing that 16 patients had high CT-ECV. Of these, 6 patients showed a positive 99 mTc-PYP study, and 6 patients were subsequently diagnosed with wild-type ATTR-CM via cardiac biopsy and genetic testing. CONCLUSIONS: CT-ECV combined with red flags could contribute to the systematic early screening of concealed ATTR-CM in AF patients undergoing catheter ablation.

Pitfalls in the diagnosis and treatment of a hypertensive patient with unilateral primary aldosteronism and contralateral pheochromocytoma: a case report.

BACKGROUND: Primary aldosteronism (PA) is a common cause of secondary hypertension, whereas pheochromocytoma is a rare cause of it. Thus, concomitant PA and pheochromocytoma is a very rare condition. CASE PRESENTATION: A 52-year-old woman was admitted to our hospital with suspected PA based on the presence of hypertension, spontaneous hypokalemia, and a high aldosterone-to-renin ratio. She had no catecholamine excess symptoms other than hypertension. Abdominal computed tomography (CT) showed a right lipid-rich adrenal mass and a left lipid-poor adrenal mass. PA was diagnosed by the captopril challenge test. The 24-h urinary fractionated metanephrines were slightly elevated. Adrenal vein sampling (AVS) confirmed that the right adrenal gland was responsible for aldosterone hypersecretion. Medical therapy with eplerenone was started because the patient refused surgery. Five years later, she requested surgery for PA. The second AVS confirmed right unilateral hyperaldosteronism, as expected. Repeated abdominal CT showed the enlargement of the left adrenal mass. The 24-h urinary fractionated metanephrines had risen to the diagnostic level. 123I- metaiodobenzylguanidine (MIBG) scintigraphy showed a marked tracer uptake in the left adrenal mass with no metastatic lesion. After preoperative management with α-blockade, laparoscopic left partial adrenalectomy was performed. Immunohistochemical examination of the tumor showed chromogranin A positivity leading to the diagnosis of left pheochromocytoma. CONCLUSIONS: We report an extremely rare case of concomitant unilateral PA and contralateral pheochromocytoma. When diagnosing unilateral PA by AVS, especially in cases with a lipid-poor adrenal mass, clinicians should rule out the possibility of the presence of pheochromocytoma before proceeding to undergo unilateral adrenalectomy. Although there is no standard treatment for this rare condition, it is essential to select personalized treatment from the perspective of conserving the adrenal gland.

Risk factors for rectal bleeding after volumetric-modulated arc radiotherapy of prostate cancer.

Background: It is crucially important to understand the risk factors for rectal bleeding after volumetric-modulated arc radiotherapy (VMAT) for prostate cancer to prevent subsequent rectal bleeding. We assayed clinical and dosimetric data to investigate the risk factors for rectal bleeding after VMAT of prostate cancer. Materials and methods: This study included 149 patients with prostate cancer who received VMAT from February, 2012 to June, 2020. Irradiated total doses were 78 Gy/39 fractions in 33 patients (22.1%), 76 Gy/38 fractions in 89 (59.7%), 74 Gy/37 fractions in 4 (2.7%), and 72 Gy/36 fractions in 23 (15.4%). We investigated multiple clinical and dosimetric factors with reference to rectal bleeding. Results: The median observation period was 38 months. Fourteen patients (9.4%) experienced rectal bleeding: five (3.4%) were classified as Grade 2, and nine (6.0%) as Grade 1. There were significant differences between Grade ≥ 1 and Grade 0 patients in the overlap region of the planning target volume (PTV) and the rectum, the rectal V30-75, and the mean rectal dose (p < 0.05). There were significant differences between Grade 2 and Grade 0-1 patients in rectal V30-65 and mean rectal dose (p < 0.05). Conclusions: Rectal bleeding occurred, but its grades and rate of occurrence were permissible. Higher rectal doses were shown to be related to rectal bleeding, and reduction of low/intermediate and mean rectal doses will be important for preventing rectal bleeding.

Vessel Occlusion using Hydrogel-Coated versus Nonhydrogel Embolization Coils in Peripheral Arterial Applications: A Prospective, Multicenter, Randomized Trial.

PURPOSE: To evaluate the safety and effectiveness of hydrogel-coated coils for vessel occlusion in the body trunk. MATERIALS AND METHODS: A total of 77 patients with various peripheral vascular lesions, treatable by embolization with coils, were randomized (hydrogel group, n = 38; nonhydrogel group, n = 39). In the hydrogel group, embolization of the target vessel was conducted using 0.018-inch hydrogel-coated coils (AZUR 18; Terumo Medical Corporation, Tokyo, Japan) with or without bare platinum coils. The nonhydrogel group received both bare platinum coils and fibered coils without the use of hydrogel-coated coils. RESULTS: Complete target vessel occlusion was accomplished in 36 patients in the hydrogel group and 37 patients in the nonhydrogel group. No major adverse events were observed in either group. The median number of coils/vessel diameter and the median total coil length/vessel diameter were significantly larger in the nonhydrogel group than in the hydrogel group (P = .005 and P = .004, respectively). The median embolization length was significantly longer in the nonhydrogel group (31.95 mm) than in the hydrogel group (23.43 mm) (P = .002). If no expansion was assumed, the median packing density in the hydrogel group was 44.9%, which was similar to that in the nonhydrogel group (46.5%) (P = .79). With full expansion assumed, the median packing density in the hydrogel group was 125.7%. CONCLUSIONS: Hydrogel-coated coils can be safely used for peripheral vascular coil embolization, and hydrogel-coated and conventional coils in combination allow for a shorter embolization segment and shorter coil length.

Image quality improvement with deep learning-based reconstruction on abdominal ultrahigh-resolution CT: A phantom study.

PURPOSE: In an ultrahigh-resolution CT (U-HRCT), deep learning-based reconstruction (DLR) is expected to drastically reduce image noise without degrading spatial resolution. We assessed a new algorithm's effect on image quality at different radiation doses assuming an abdominal CT protocol. METHODS: For the normal-sized abdominal models, a Catphan 600 was scanned by U-HRCT with 100%, 50%, and 25% radiation doses. In all acquisitions, DLR was compared to model-based iterative reconstruction (MBIR), filtered back projection (FBP), and hybrid iterative reconstruction (HIR). For the quantitative assessment, we compared image noise, which was defined as the standard deviation of the CT number, and spatial resolution among all reconstruction algorithms. RESULTS: Deep learning-based reconstruction yielded lower image noise than FBP and HIR at each radiation dose. DLR yielded higher image noise than MBIR at the 100% and 50% radiation doses (100%, 50%, DLR: 15.4, 16.9 vs MBIR: 10.2, 15.6 Hounsfield units: HU). However, at the 25% radiation dose, the image noise in DLR was lower than that in MBIR (16.7 vs. 26.6 HU). The spatial frequency at 10% of the modulation transfer function (MTF) in DLR was 1.0 cycles/mm, slightly lower than that in MBIR (1.05 cycles/mm) at the 100% radiation dose. Even when the radiation dose decreased, the spatial frequency at 10% of the MTF of DLR did not change significantly (50% and 25% doses, 0.98 and 0.99 cycles/mm, respectively). CONCLUSION: Deep learning-based reconstruction performs more consistently at decreasing dose in abdominal ultrahigh-resolution CT compared to all other commercially available reconstruction algorithms evaluated.

Hyperintense Liver Masses at Hepatobiliary Phase Gadoxetic Acid-enhanced MRI: Imaging Appearances and Clinical Importance.

Gadoxetic acid, a hepatobiliary-specific contrast medium used for MRI, is becoming increasingly important in the detection and characterization of hepatic mass lesions. This medium is taken up by functioning hepatocytes, and the liver parenchyma is strongly enhanced in the hepatobiliary phase (HBP), during which hepatic mass lesions without functioning hepatocytes commonly show hypointensity. However, some hepatic mass lesions show hyperintensity in the HBP. Focal nodular hyperplasia (FNH) and FNH-like lesions show hyperintensity in the HBP owing to the uptake of gadoxetic acid by hyperplastic normal hepatocytes. The tumor cells of some types of hepatocellular adenoma (eg, ß-catenin-activated type, inflammatory type) and hepatocellular carcinoma (eg, green hepatoma) can show uptake of gadoxetic acid. Retention of gadoxetic acid in the extracellular space can cause hyperintensity of fibrotic tumors or hemangiomas during the HBP owing to the extracellular contrast agent characteristics of gadoxetic acid. During the HBP, peritumoral retention is observed in some tumors, such as hepatocellular carcinomas, gastrointestinal stromal tumors, and neuroendocrine tumors. Gadoxetic acid is excreted into the bile; therefore, biliary tract enhancement can be observed in the cystic components of intraductal papillary neoplasms of the bile duct. Intratumoral bile ducts can be observed in malignant lymphomas. Knowledge of these specific mechanisms, which can cause hyperintensity during the HBP depending on the pathologic or molecular background, is important not only for precise imaging-based diagnoses but also for understanding the pathogenesis of hepatic mass lesions. ©RSNA, 2019 See discussion on this article by Lalwani.

Improved visualization of a fine intrahepatic biliary duct on drip infusion cholangiography-computed tomography: Impact of knowledge-based iterative model reconstruction.

AIM: The purpose of this study was to investigate the visualization of fine biliary ducts with knowledge-based iterative model reconstruction (IMR) in low-dose drip infusion computed tomography (CT) cholangiography (DIC-CT) as compared with filtered back projection (FBP) and hybrid iterative reconstruction (iDose4 ). METHODS: A total of 38 patients underwent DIC-CT for living donor liver transplantation. CT was performed approximately 20 min after the end of the infusion of meglumine iotroxate (100 mL). Images were reconstructed using FBP, iDose4 , and IMR, and 1-mm slice images at fixed window level and width were prepared for assessment. Two reviewers independently evaluated the quality of visualization of the fine biliary ducts of the caudate lobe (B1) using a 5-point scale. The visualization scores of three reconstructed images were compared using the Kruskal-Wallis test and Mann-Whitney U-test. RESULTS: For reviewer 1, the visualization score of IMR was significantly higher than that of FBP (P = 0.012), and tended to be higher than that of iDose4 (P = 0.078). For reviewer 2, the visualization score of IMR was significantly higher than those of both FBP and iDose4 (P < 0.01). CONCLUSIONS: IMR showed better visualization of B1 on DIC-CT than FBP or iDose4 . DIC-CT reconstructed with IMR may be useful to the anatomical grasp of biliary tracts in cases of hepatectomy.

Low Radiation Dose and High Image Quality of 320-Row Coronary Computed Tomography Angiography Using a Small Dose of Contrast Medium and Refined Scan Timing Prediction.

OBJECTIVE: The aim of the study was to investigate the feasibility of coronary computed tomography (CT) angiography with a low kilovoltage peak scan and a refined scan timing prediction using a small contrast medium (CM) dose. METHODS: In protocol A, 120-kVp scanning and a standard CM dose were used. The scan timing was fixed. In protocol B, 80 kVp and a 60% CM dose were used. The scan timing was determined according to the interval from the CM arrival to the peak time in the ascending aorta. We measured the CT number and recorded the radiation dose. RESULTS: Higher CT numbers were observed in the left circumflex (proximal, P = 0.0235; middle, P = 0.0007; distal, P < 0.0001) in protocol B compared with protocol A. The radiation dose in protocol B was significantly lower than in protocol A (2.2 ± 0.9 vs 4.3 ± 1.7 mSv). CONCLUSIONS: Low-contrast, low-radiation dose, high-image quality coronary CT angiography can be performed with low kilovoltage peak scanning and a refined scan timing prediction.

Amide proton transfer imaging to predict tumor response to neoadjuvant chemotherapy in locally advanced rectal cancer.

BACKGROUND AND AIM: The amount of proteins and peptides can be estimated with amide proton transfer (APT) imaging. Previous studies demonstrated the usefulness of APT imaging to predict tumor malignancy. We determined whether APT imaging can predict the tumor response to neoadjuvant chemotherapy (NAC) in patients with locally advanced rectal cancer (LARC). METHODS: Seventeen patients with LARC who underwent a pretherapeutic magnetic resonance examination including APT imaging and NAC (at least two courses) were enrolled. The APT-weighted imaging (WI) signal intensity (SI) (%) was defined as magnetization transfer ratio asymmetry (MTRasym ) at the offset of 3.5 ppm. Each tumor was histologically evaluated for the degree of degeneration and necrosis and then classified as one of five histological Grades (0, none; 1a, less than 1/3; 1b, 1/3 to 2/3; 2, more than 2/3; 3, all). We compared the mean APTWI SIs of the tumors between the Grade 0/1a/1b (low-response group) and Grade 2/3 (high-response group) by Student's t-test. We used receiver operating characteristics curves to determine the diagnostic performance of the APTWI SI for predicting the tumor response. RESULTS: The mean APTWI SI of the low-response group (n = 12; 3.05 ± 1.61%) was significantly higher than that of the high-response group (n = 5; 1.14 ± 1.13%) (P = 0.029). The area under the curve for predicting the tumor response using the APTWI SI was 0.87. When ≥2.75% was used as an indicator of low-response status, 75% sensitivity and 100% specificity of the APTWI SI were obtained. CONCLUSION: Pretherapeutic APT imaging can predict the tumor response to NAC in patients with LARC.

Amide Proton Transfer MR Imaging of Endometrioid Endometrial Adenocarcinoma: Association with Histologic Grade.

Purpose To evaluate the utility of amide proton transfer (APT) imaging in estimating histologic grades of endometrioid endometrial adenocarcinoma (EEA). Materials and Methods The institutional review board approved this prospective study. Between June 2012 and March 2016, 32 patients with EEA underwent magnetic resonance (MR) imaging. After their surgical procedures, their EEAs were confirmed pathologically and classified into histologic grades: grade 1 (n = 11), grade 2 (n = 11), and grade 3 (n = 10). The APT signal intensities (SIs) and the mean and minimum apparent diffusion coefficients (ADCs) of the three grades were calculated and compared. Spearman rank correlation coefficient was also calculated between the APT SIs and histologic grades, and between the ADCs and histologic grades. Results The Spearman correlation coefficient with histologic grade of the APT SIs, the mean ADC, and the minimum ADC were 0.55 (P = .001), 0.03 (P = .84), and -0.30 (P = .09), respectively. The average APT SIs and the mean and minimum ADCs were 2.2% ± 0.2 (standard deviation), 0.9 × 10-3 mm2/sec ± 0.2, and 0.6 × 10-3 mm2/sec ± 0.1 for grade 1; 3.2% ± 0.3, 0.8 × 10-3 mm2/sec ± 0.1, and 0.5 × 10-3 mm2/sec ± 0.1 for grade 2; and 3.7% ± 0.3, 0.9 × 10-3 mm2/sec ± 0.1, and 0.5 × 10-3 mm2/sec ± 0.1 for grade 3, respectively. The APT SIs of grade 3 EEA were significantly higher than those of grade 1 EEA (P = .01), but other pairwise comparisons did not reveal any significant differences (P = .06-.51). The mean and minimum ADCs showed no significant differences among the three histologic grades (P =.13-.51). Conclusion The APT SI was positively correlated with the histologic grades of EEA. © RSNA, 2017 Online supplemental material is available for this article.

The prevalence of transpancreatic common hepatic artery and coexisting variant anatomy.

We studied the prevalence of the transpancreatic common hepatic artery (tp-CHA) and coexisting variant anatomy. The study group comprised 788 consecutive liver transplant donor candidates who had undergone thin-section multidetector-row computed tomography (MDCT) studies to investigate vascular anatomy. Multiplanar reformatted (MPR) images obtained from the arterial phase were retrospectively reviewed to assess the presence/absence of the tp-CHA. Five cases of tp-CHA with pancreaticobiliary tumors were also included in an investigation of the presence/absence of variant hepatic arteries, celiac stenosis, and circumportal pancreas. Three of the 788 (0.38%) donor candidates had a tp-CHA. Overall, eight tp-CHA cases were assessed for coexisting variant anatomy. Seven of these eight cases had a hepatomesenteric trunk, six had celiac stenosis, and two had a circumportal pancreas. The prevalence of the tp-CHA was 0.38% (approx. one in 260 in normal populations). A tp-CHA can commonly be associated with a hepatomesenteric trunk and celiac stenosis. A circumportal pancreas can also coexist with a tp-CHA. Clin. Anat. 31:598-604, 2018. © 2017 Wiley Periodicals, Inc.

Mass-forming intrahepatic cholangiocarcinoma: Enhancement patterns in the arterial phase of dynamic hepatic CT - Correlation with clinicopathological findings.

OBJECTIVES: To evaluate the relationship between the enhancement pattern of intrahepatic cholangiocarcinomas (ICCs) in the hepatic arterial phase (HAP) of dynamic hepatic CT and the clinicopathological findings with special reference to the perihilar type and the peripheral type. METHODS: Forty-seven patients with pathologically proven ICCs were enrolled. Based on the enhancement pattern in the HAP, the lesions were classified into three groups: a hypovascular group (n=13), rim-enhancement group (n=18), and hypervascular group (n=16). The clinicopathological findings were compared among the three groups. RESULTS: Perihilar-type ICCs were significantly more frequently observed in the hypovascular group than in the rim-enhancement and hypervascular groups (p=0.006 and p <0.001, respectively). Lymphatic invasion, perineural invasion, and biliary invasion were significantly more frequent in the hypovascular group than the rim- enhancement group (p=0.001, p=0.025 and p=0.029, respectively) or hypervascular group (p <0.001, p <0.001 and p=0.025, respectively). Patients with hypovascular lesions showed significantly poorer disease-free survival than patients with rim-enhancing or hypervascular lesions (p=0.001 and p=0.001, respectively). Hypovascularity was an independent preoperative prognostic factor for disease-free survival (p<0.001). CONCLUSIONS: Hypovascular ICCs in the HAP tend to be of perihilar type and to have more malignant potential than other ICCs. KEY POINTS: • Hypovascular ICCs have greater malignant potential than rim-enhancing and hypervascular ICCs. • Hypovascular ICCs show a higher frequency of perihilar-type ICCs. • Perihilar-type ICCs do not always display distal ductal wall thickening.

Prognostic significance of contrast-enhanced CT attenuation value in extrahepatic cholangiocarcinoma.

OBJECTIVES: To determine whether washout characteristics of dynamic contrast-enhanced computed tomography (CT) could predict survival in patients with extrahepatic cholangiocarcinoma (EHC). METHODS: This study collected 46 resected cases. All cases were examined by dynamic contrast study on multidetector-row CT. Region-of-interest measurements were obtained at the non-enhanced, portal venous phase and delayed phase in the tumour and were used to calculate the washout ratio as follows: [(attenuation value at portal venous phase CT - attenuation value at delayed enhanced CT)/(attenuation value at portal venous phase CT - attenuation value at unenhanced CT)] × 100. On the basis of the median washout ratio, we classified the cases into two groups, a high-washout group and low-washout group. Associations between overall survival and various factors including washout rates were analysed. RESULTS: The median washout ratio was 29.4 %. Univariate analysis revealed that a lower washout ratio, venous invasion, lymphatic permeation and lymph node metastasis were associated with shorter survival. Multivariate analysis identified the lower washout ratio as an independent prognostic factor (hazard ratio, 3.768; p value, 0.027). CONCLUSIONS: The washout ratio obtained from the contrast-enhanced CT may be a useful imaging biomarker for the prediction of survival of patients with EHC. KEY POINTS: • Dynamic contrast study can evaluate the aggressiveness of extrahepatic cholangiocarcinoma. • A lower washout ratio was an independent prognostic factor for overall survival. • CT can predict survival and inform decisions on surgical options or chemotherapy.

Apparent diffusion coefficient: An associative factor for recurrence after nephrectomy in localized renal cell carcinoma.

PURPOSE: To investigate whether the apparent diffusion coefficient (ADC) of a tumor is associated with recurrence after nephrectomy in renal cell carcinoma (RCC) MATERIALS AND METHODS: We retrospectively studied 49 patients with localized RCC who underwent 1.5T magnetic resonance imaging (MRI) including diffusion-weighted imaging preoperatively. Fifteen patients had recurrent disease after surgery. The ADC was measured by placing a region-of-interest in a solid region of each tumor on the ADC map. We named the average value of the three ADC values the "average ADC" and the lowest ADC value among the three as the "minimum ADC." The correlations between clinicopathological factors including patient age and gender, tumor side, tumor size, growth/invasion pattern, Fuhrman grade, histological subtype, venous invasion, average and minimum ADCs, and disease-free survival were analyzed by Cox proportional hazards model. RESULTS: In univariate analysis, tumor size, venous invasion, mean ADC, and minimum ADC showed significant correlations with disease-free survival (P < 0.05). In multivariate analysis, only venous invasion and minimum ADC were significant (P < 0.05). The 5-year disease-free survival rate of the low minimum ADC group was 51.6%, while that of the high minimum ADC group was 85.1%. CONCLUSION: The minimum ADC of a tumor, although not as pronounced as venous invasion, was found to be an independent associative factor for recurrence after nephrectomy in patients with localized RCC.

Differentiation of early gastric cancer with ulceration and resectable advanced gastric cancer using multiphasic dynamic multidetector CT.

OBJECTIVES: Early gastric cancer with ulceration (EGC-U) mimics advanced gastric cancer (AGC), as EGC-Us and ACGs often have similar endoscopic appearance to ulceration. The purpose of this retrospective study was to determine whether multiphasic dynamic multidetector CT (MDCT) can help differentiate EGC-Us from AGCs. METHODS: Patients with EGC-Us with ulcer stages Ul-III or IV and AGCs with tumour stages T2 to T4a were enrolled. MDCT images were obtained 40 s (arterial phase), 70 s (portal phase) and 240 s (delayed phase) after injection of non-ionic contrast material. Two readers independently measured the attenuation values of the lesions by placing regions of interest. We compared the EGC-Us and AGCs using the mean attenuation values in each phase and peak enhancement phase. We analysed the diagnostic performance of CT for differentiating EGC-Us from AGCs. RESULTS: Forty cases (16 EGC-Us and 24 AGCs) were analysed. The mean attenuation values of the EGC-Us were significantly lower than those of the AGCs in both the arterial and portal phases (all p < 0.0001 for each reader). The peak enhancement was significantly different between the EGC-Us and AGCs for both readers (Reader 1, p = 0.0131; Reader 2, p = 0.0006). CONCLUSION: Multiphasic dynamic contrast-enhanced MDCT can help differentiate EGC-Us from AGCs. KEY POINTS: • Early gastric cancer with ulceration and advanced gastric cancer have similar endoscopic appearances. • EGC-U shows significantly lower attenuation values in both arterial and portal phases. • Multiphasic dynamic contrast-enhanced MDCT differentiates EGC-U from AGC.

Amide proton transfer (APT) magnetic resonance imaging of prostate cancer: comparison with Gleason scores.

OBJECTIVE: To evaluate the utility of amide proton transfer (APT) imaging in estimating the Gleason score (GS) of prostate cancer (Pca). MATERIALS AND METHODS: Sixty-six biopsy-proven cancers were categorized into four groups according to the GS: GS-6 (3 + 3); GS-7 (3 + 4/4 + 3); GS-8 (4 + 4) and GS-9 (4 + 5/5 + 4). APT signal intensities (APT SIs) and apparent diffusion coefficient (ADC) values of each GS group were compared by one-way analysis of variance with Tukey's HSD post hoc test. RESULTS: The mean and standard deviation of the APT SIs (%) and ADC values (×10(-3) mm(2)/s) were as follows: GS-6, 2.48 ± 0.59 and 1.16 ± 0.26; GS-7, 5.17 ± 0.66 and 0.92 ± 0.18; GS-8, 2.56 ± 0.85 and 0.86 ± 0.17; GS-9, 1.96 ± 0.75 and 0.85 ± 0.18, respectively. The APT SI of the GS-7 group was highest, and there were significant differences between the GS-6 and GS-7 groups and the GS-7 and GS-9 groups (p < 0.05). The ADC value of the GS-6 group was significantly higher than each value of the GS-7, GS-8, and GS-9 groups (p < 0.05), but no significant differences were obtained among the GS-7, GS-8, and GS-9 groups. CONCLUSION: The mean APT SI in Pca with a GS of 7 was higher than that for the other GS groups.

T1 ρ Relaxation of the liver: A potential biomarker of liver function.

PURPOSE: To investigate the diagnostic potential of T1 ρ relaxation for assessing liver function, liver fibrosis, or liver necroinflammation in patients with chronic liver disease (CLD). MATERIALS AND METHODS: We obtained T1 ρ maps of the liver for 53 patients with or without CLD. We measured the T1 ρ values of the liver and correlated them with the results of laboratory tests and histological examinations. Pearson's correlation coefficients (r) were calculated between the T1 ρ values and blood serum parameters including the retention rates at 15 minutes after an injection of indocyanine green (ICG-R15). Spearman's rank correlation coefficients were calculated between the T1 ρ values and the scores of liver fibrosis or liver necroinflammation. RESULTS: The T1 ρ values showed significant positive correlations with the serum levels of total bilirubin (r = 0.31, P < 0.05), direct bilirubin (r = 0.32, P < 0.05), and ICG-R15 (r = 0.46, P < 0.05), and significant negative correlations with the serum levels of albumin (r = -0.33, P < 0.05) and γ-glutamyl transpeptidase (r = -0.28, P < 0.05). However, there were no significant correlations between the T1 ρ value and the scores of liver fibrosis (P = 0.95) or liver necroinflammation (P = 0.86). CONCLUSION: T1 ρ relaxation has potential as a biomarker of liver function in patients with CLD. However, it may not be suitable to estimate liver fibrosis or liver necroinflammation.

Three-dimensional T2-weighted imaging for liver MRI: clinical values of tissue-specific variable refocusing flip-angle turbo spin echo imaging.

PURPOSE: To assess the clinical utility of tissue-specific variable refocusing flip-angle (VRFA) turbo-spin echo imaging for three-dimensional T2-weighted imaging (3D-T2WI) of the liver. MATERIALS AND METHODS: Fifty-nine patients were scanned with three types of fat-suppressed T2WI for the comparison: two-dimensional single-shot turbo spin echo T2WI (ssT2WI), 3D-T2WI with tissue-specific VRFA (VISTA-TSV), and 3D-T2WI with low-constant VRFA (VISTA). Qualitatively, artifacts in the left and right lobes of the liver and black-blood effects in the liver were compared using the Wilcoxon signed-rank test with the Bonferroni correction. The detection and correct characterization rates of liver lesions were compared using McNemar's test. RESULTS: VISTA-TSV showed reduced artifacts in the left and right lobes of the liver compared with VISTA (P < 0.017). The artifacts shown by VISTA-TSV were equivalent to those shown by ssT2WI. The black-blood effects of VISTA-TSV and VISTA were better than that of ssT2WI (P < 0.017). VISTA-TSV showed the best detection and correct characterization rate of liver lesions among the three imaging techniques (P < 0.05). CONCLUSION: 3D-T2WI with tissue-specific VRFA can reduce artifacts of the liver, sufficiently suppress the signal in blood vessels, and has a potential to improve the detection and correct characterization rates of liver lesions.

Hepatocellular carcinoma: clinical significance of signal heterogeneity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging.

OBJECTIVES: To clarify the relationship between the biological behaviour of hepatocellular carcinomas (HCCs) and their signal intensity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging with a special focus on the signal heterogeneity. METHODS: A total of 68 patients with 70 pathologically proven HCCs were enrolled. On the basis of the signal intensity in the hepatobiliary phase, the lesions were classified into three groups: group 1, homogeneous hypointensity (n = 44); group 2, heterogeneous hyperintensity (n = 20); and group 3, homogeneous hyperintensity (n = 6). The clinicopathological findings were compared among the three groups. RESULTS: The tumour size and the serum level of protein induced by vitamin K absence or antagonist-II (PIVKA-II) were significantly higher in group 2 compared to group 1 (p = 0.0155, p = 0.0215, respectively) and compared to group 3 (p = 0.0330, p = 0.0220, respectively). The organic anion transporting polypeptide 8 (OATP8) expression in group 2 and group 3 was significantly higher than in group 1 (p < 0.0001, p < 0.0001, respectively). Group 2 showed a significantly lower disease-free survival rate compared to group 1 (p = 0.0125), and group 2 was an independent prognostic factor for disease-free survival (p = 0.0308). CONCLUSIONS: HCCs in the hepatobiliary phase that are heterogeneously hyperintense on gadoxetic acid-enhanced MR imaging have more malignant potential than other types of HCCs. KEY POINTS: • Heterogeneous uptake of gadoxetic acid suggests more malignant potential in HCC • Uptake of gadoxetic acid does not suggest less malignancy in HCC • Evaluation of signal heterogeneity on gadoxetic acid-enhanced MR imaging is useful.