Value of gadoxetic acid-enhanced MR imaging for preoperative prediction of future liver regeneration after hemihepatectomy.

PURPOSE: Liver resection is currently considered the most effective treatment for patients with liver cancer. To the best of our knowledge, no study has investigated the association between gadoxetic acid-enhanced magnetic resonance imaging (MRI) findings and liver regeneration in patients who underwent hemihepatectomy. We aimed to clarify the relationship between the signal intensity (SI) of the liver parenchyma on gadoxetic acid-enhanced MRI and the degree of liver regeneration in patients who underwent hemihepatectomy. MATERIALS AND METHODS: Forty-one patients who underwent gadoxetic acid-enhanced MRI before hemihepatectomy were enrolled. We calculated the liver-to-erector spinae muscle SI ratio (LMR) in the hepatobiliary phase and the precontrast images. ΔLMR was calculated using the following equation: ΔLMR = (LMR in the hepatobiliary phase-LMR in the precontrast image)/LMR in the precontrast image. The preoperative and postoperative remnant liver volumes (LVs) were calculated using CT volumetry. We calculated the resection rate (RR) and liver regeneration index (LRI) using the following formulas: RR = Resected LV/Total LV × 100 and LRI = (postoperative remnant LV-preoperative remnant LV)/preoperative remnant LV × 100. The relationships among LRI, imaging, and clinicopathological factors were analyzed. RESULTS: Univariate analysis showed RR and ΔLMR showed a positive correlation with LRI (ρ = 0.4133, p = 0.0072 and ρ = 0.7773, p < 0.001, respectively). Spleen volume showed a negative correlation with LRI (ρ = -0.3138, p = 0.0486). Stepwise multiple regression analysis showed ΔLMR and RR were independently correlated with LRI (ß coefficient = 44.8771, p = 0.0198 and ß coefficient = 1.9653, p < 0.001, respectively). CONCLUSION: ΔLMR may serve as a preoperative predictor of liver regeneration in patients undergoing hemihepatectomy.

Multiparametric assessment of microvascular invasion in hepatocellular carcinoma using gadoxetic acid-enhanced MRI.

PURPOSE: To elucidate how precisely microvascular invasion (MVI) in hepatocellular carcinoma (HCC) can be predicted using multiparametric assessment of gadoxetic acid-enhanced MRI. METHODS: In this retrospective single-center study, patients who underwent liver resection or transplantation of HCC were evaluated. Data obtained in patients who underwent liver resection were used as the training set. Nine kinds of MR findings for predicting MVI were compared between HCCs with and without MVI by univariate analysis, followed by multiple logistic regression analysis. Using significant findings, a predictive formula for diagnosing MVI was obtained. The diagnostic performance of the formula was investigated in patients who underwent liver resection (validation set 1) and in patients who underwent liver transplantation (validation set 2) using a receiver operating characteristic curve analysis. The area under the curves (AUCs) of these three groups were compared. RESULTS: A total of 345 patients with 356 HCCs were selected for analysis. Tumor diameter (D) (P = 0.021), tumor washout (TW) (P < 0.01), and peritumoral hypointensity in the hepatobiliary phase (PHH) (P < 0.01) were significantly associated with MVI after multivariate analysis. The AUCs for predicting MVI of the predictive formula were as follows: training set, 0.88 (95% confidence interval (CI) 0.82,0.93); validation set 1, 0.81 (95% CI 0.73,0.87); validation set 2, 0.67 (95% CI 0.51,0.80). The AUCs were not significantly different among three groups (training set vs validation set 1; P = 0.15, training set vs validation set 2; P = 0.09, validation set 1 vs validation set 2; P = 0.29, respectively). CONCLUSION: Our multiparametric assessment of gadoxetic acid-enhanced MRI performed quite precisely and with good reproducibility for predicting MVI.

Safety and clinical contribution of computed tomography-guided biopsy for cervical spine lesion.

INTRODUCTION: The purpose is to clarify the safety and clinical contribution of computed tomography (CT)-guided percutaneous needle-biopsy for patients with cervical spine lesion. MATERIAL AND METHODS: Between June 2015 and August 2022, CT-guided percutaneous needle biopsies were performed for 15 cervical spine lesions of 15 patients (8 male, 7 female; 2-81 years old). The technical success, clinical contribution, and safety were evaluated. Technical success was defined as the completion of the biopsy procedure. Clinical contribution was defined as any contribution to the therapeutic strategy. Safety was assessed by the Common Terminology Criteria for Adverse Events, version 5.0. RESULTS: The technical success rate was 100%. In all 15 patients, nontarget organs (e.g., major vessels, spinal cord) could be avoided. The post-biopsy histological diagnoses were myeloma (n = 2), metastatic adenocarcinoma (n = 2), chordoma (n = 2), Langerhans cell histiocytosis (n = 3), and one case each of malignant lymphoma, schwannoma, pyogenic spondylitis, non-pyogenic spondylitis, degenerative change, and non-pathological fracture. All of these diagnoses contributed to the therapeutic strategy decisions. One case of grade 2 pain was observed, but no complications with grade 3 or more were observed during or after the biopsies. CONCLUSION: CT-guided percutaneous needle biopsies for cervical spine lesions were safe and clinically beneficial.

Effect of lipiodol marking before CT-guided cryoablation on the outcome of sporadic renal cell carcinoma.

PURPOSE: This retrospective study evaluates the impact of preoperative lipiodol marking on the outcomes of computed tomography (CT)-guided cryoablation for histologically diagnosed sporadic renal cell carcinoma (RCC). METHODS: This study analyzed the data of 173 patients who underwent CT-guided cryoablation for histologically proven sporadic RCC at a single institution between April 2014 and December 2020. The local control rate (LCR), recurrence-free survival rate (RFSR), overall survival rate (OSR), changes in renal function, and complications in patients with (n = 85) and without (n = 88) preoperative lipiodol marking were compared. RESULTS: The 5-year LCR and 5-year RFSR were significantly higher in patients with lipiodol marking (97.51% and 93.84%, respectively) than in those without (72.38% and 68.10%, respectively) (P value <0.01, log-rank test). There were no significant differences between the two groups regarding the 5-year OSR (97.50% vs. 86.82%) or the deterioration in chronic kidney disease stage (12.70% vs. 16.43%). Grade ≥3 complications occurred in patients with lipiodol marking (n = 2, retroperitoneal hematoma and cerebral infarction in 1 patient each) and without (n = 5; urinary fistula in 2, colonic perforation in 2, urinary infection in 1). CONCLUSION: Lipiodol marking before CT-guided cryoablation for sporadic RCC is a feasible approach to improving local control and RFS while mitigating the decline in renal function. Additionally, it may help reduce complications.

Impact of portal-phase signal intensity of dynamic gadoxetic acid-enhanced magnetic resonance imaging in hepatocellular carcinoma.

PURPOSE: To evaluate the prognostic impact of dynamic gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) in patients with hepatocellular carcinoma (HCC). METHODS: We retrospectively reviewed the data of 206 patients with HCC who underwent preoperative Gd-EOB-DTPA-enhanced MRI and hepatectomy and quantitatively evaluated the signal intensity ratio of the tumor to the surrounding liver tissue in the portal phase (SIRPP). We verified the survival rates and assessed the prognostic factors associated with overall survival (OS) and recurrence-free survival (RFS) using SIRPP. RESULTS: Multivariate analysis revealed that the independent predictive factors for poorly-differentiated HCC were α-fetoprotein > 20 ng/mL (hazard ratio [HR]: 3.1909, 95% confidence interval [CI]: 1.3464-7.5622, p = .0084) and SIRPP ≤ 0.85 (HR: 3.7155, 95% CI: 1.521-9.076, p = .004). The 5-year OS and RFS rates in the high and low SIRPP groups were 83.2 and 52.1%, respectively (p < .0001) and 49.7 and 18.5%, respectively (p = .0003). Multivariate analysis revealed that SIRPP ≤ 0.68 was an independent prognostic factor related to OS (HR: 4.4537, 95% CI: 1.6581-11.9626, p = .003). CONCLUSION: The SIRPP of preoperative Gd-EOB-DTPA-enhanced MRI might predict the histological differentiation and prognosis of HCC.

Diagnostic accuracy of percutaneous core biopsy before cryoablation for small-sized renal cell carcinoma.

PURPOSE: To retrospectively determine the diagnostic accuracy of a percutaneous core biopsy performed before cryoablation for small-sized renal cell carcinoma. METHODS: In this study, 216 patients underwent a percutaneous core biopsy for 242 renal lesions suspected to be renal cell carcinoma on image findings before cryoablation at Kyushu University Hospital. We calculated the success rate of the histological diagnosis and investigated factors that may have contributed to the diagnostic success. Complications caused by the biopsy procedure were also evaluated. RESULTS: The histological diagnosis was successful in 203 lesions (82.8%). The success rate of the histological diagnosis was 65.4% (34/52 cases) for tumors with a diameter of ≤15 mm and 88.9% (169/190 cases) for those >15 mm. Therefore, tumor diameter was a factor contributing to the histological diagnosis success rate in both univariate and multivariable analyses (P < 0.001). For lesions with a tumor diameter ≤15 mm, the histological diagnosis success rates increased from 50.0% to 76.2% in the presence of pre-lipiodol marking and to 85.7% when the biopsy procedure was performed separately from cryoablation; the latter was statistically significant (P = 0.039). Major complications that may have been caused by the biopsy procedure were grade 3 bleeding and tract seeding (one case each). CONCLUSION: Percutaneous core biopsy in cryoablation for small-sized renal cell carcinoma had a high diagnostic rate and was safely performed. For lesions with a tumor diameter ≤15 mm, a separate biopsy procedure and pre-lipiodol marking may improve the diagnostic accuracy.

Clinical association between intraoperative indocyanine green fluorescence imaging pattern, preoperative Gd-EOB-DTPA-enhanced magnetic resonance imaging findings, and histological differentiation in hepatocellular carcinoma.

AIM: We aimed to evaluate the association between the intraoperative indocyanine green (ICG) fluorescence imaging (FI) pattern, preoperative magnetic resonance imaging (MRI) findings using gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA), preoperative diffusion-weighted imaging (DWI) of MRI, and histological differentiation of hepatocellular carcinoma (HCC). METHODS: We retrospectively reviewed the data for 80 tumors of 64 patients. Intraoperative ICG FI patterns were classified into cancerous or rim-positive type. We evaluated the signal intensity ratio of the tumor and the surrounding liver tissue in the portal phase (SIRPP) and intensity in the hepatobiliary phase (HBP) of Gd-EOB-DTPA-enhanced MRI, the apparent diffusion coefficient (ADC) in the DWI of MRI, and clinicopathologic factors. RESULTS: In the rim-positive group, the rate of poorly differentiated HCC and hypointensity type in HBP were significantly higher, and SIRPP and ADC were significantly lower than the rim-negative group. In the cancerous group, the rate of well or moderately differentiated HCC and hyperintensity type in HBP, SIRPP, and ADC were significantly higher than the noncancerous group. Multivariate analysis identified low SIRPP, low ADC, and hypointensity type in HBP as the significant predictive factors for rim-positive HCC and high SIRPP, high ADC, and hyperintensity type in HBP as the significant predictive factors for cancerous HCC. The positive rate of programmed cell death 1-ligand 1 and vessels that encapsulate tumor clusters status of the rim-positive HCC and HCC with low SIRPP were significantly higher than the control group. CONCLUSIONS: The intraoperative ICG FI pattern of HCC closely correlated with histological differentiation, preoperative SIRPP and intensity type in the Gd-EOB-DTPA MRI, and preoperative ADC in the DWI of MRI.

Extracellular volume fraction determined by dual-layer spectral detector CT: Possible role in predicting the efficacy of preoperative neoadjuvant chemotherapy in pancreatic ductal adenocarcinoma.

PURPOSE: To clarify the relationship between extracellular volume (ECV) measured by dual-energy CT (DECT) and efficacy of preoperative neoadjuvant chemotherapy (NAC) in patients with pancreatic ductal adenocarcinoma (PDAC), as compared with single-energy CT (SECT). METHODS: We enrolled 67 patients with PDAC who underwent dynamic contrast-enhanced CT with a dual-energy CT system prior to NAC. Attenuation values were measured on unenhanced and the equilibrium-phase 120-kVp equivalent CT images for PDAC and the aorta. ΔHU-tumor, ΔHU-tumor/ΔHU-aorta, and SECT-ECV were calculated. Iodine densities of the tumor and aorta were measured in the equilibrium phase, and DECT-ECV of the tumor was calculated. Response to NAC was evaluated and the correlation between imaging parameters and response to NAC was statistically assessed. RESULTS: Tumor DECT-ECVs were significantly lower in the response group (n = 7) than in the non-response group (n = 60), with most significant difference (p = 0.0104). DECT-ECV showed highest diagnostic value with an Az value of 0.798. When using the optimal cut off value of DECT-ECV (<26.0 %), sensitivity, specificity, accuracy, positive predictive value, and negative value for predicting response group were 71.4 %, 85.0 %, 83.6 %, 35.7 % and 96.2 %, respectively. CONCLUSION: PDAC with lower DECT-ECV can potentially show better response to NAC. DECT-ECV might be a useful biomarker for predicting response to NAC in patients with PDAC.

MR Prediction of Malignant Switch With the Cyst Fluid's T2 Value in Intraductal Papillary Mucinous Neoplasm of the Pancreas: A Preliminary Study.

BACKGROUND/AIM: We investigated whether the malignant switch of intraductal papillary mucinous neoplasm (IPMN) of the pancreas can be predicted by using the T1ϱ, T2, and apparent diffusion coefficient (ADC) values of cyst fluid. PATIENTS AND METHODS: We retrospectively analyzed the magnetic resonance (MR) images of 60 patients (26 males, 34 females, mean age 61 years) with branch-duct type and mixed-type IPMNs. The IPMNs were diagnosed clinically in 39 patients and histologically in 21 patients. The malignant potential was classified by MR imaging based on the international consensus guidelines for the management of IPMN established in 2017. Morphologically, 42 patients had "worrisome features" and three had "high-risk stigmata." Histologically, 14 lesions were diagnosed as low-grade dysplasia and seven as intermediate-grade dysplasia. The T1ϱ, T2, and ADC values of cyst fluid in each patient's largest cyst were measured on the same slice, avoiding solid components. Spearman's rank correlation test was used to determine the correlation between the morphological malignancy and the T1ϱ, T2, and ADC values. These values were also compared between the low-grade and intermediate-grade groups by Mann-Whitney U-test. RESULTS: There was a significant rank-correlation between the morphological classification and T2 value (p=0.04). The T2 value of the intermediate-grade group was significantly higher than that of the low-grade group (p=0.03). No significant correlations were morphologically or histologically obtained regarding T1ϱ and ADC. CONCLUSION: The T2 value of cyst fluid together with other MR-signs may be useful for predicting the malignant switch in IPMN of the pancreas.

Association between Sarcopenia and Omega-3 Polyunsaturated Fatty Acid in Patients with Hepatocellular Carcinoma.

Introduction: This study aimed to validate whether preoperative sarcopenia can predict long-term outcomes in patients with hepatocellular carcinoma (HCC) and identify the associations between sarcopenia and polyunsaturated fatty acids (PUFAs). Methods: This large, retrospective study included 353 patients who underwent hepatic resection for HCC and preoperative computed tomography scans. Skeletal muscle mass was measured at the third lumbar vertebrae. The cutoff value for sarcopenia followed the Japan Society of Hepatology's assessment criteria for sarcopenia. Results: Ninety-three patients (26.3%) with preoperative sarcopenia were enrolled. These patients had a significantly lower body mass index (p < 0.0001) and serum albumin level (p = 0.0070) as well as a higher rate of advanced-stage cancer (p = 0.0062) than those without sarcopenia. Patients with sarcopenia had significantly shorter overall survival than the other patients before (p = 0.0001) and after (p = 0.0415) propensity score matching. The sarcopenia group was significantly associated with low levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which were categorized based on omega-3 PUFAs, compared with those in the non-sarcopenia group (p = 0.0030 and p = 0.0135). Conclusions: We demonstrated an association between sarcopenia and the long-term prognosis in patients with HCC. Low EPA and DHA levels were associated with preoperative sarcopenia. Further prospective studies are needed to investigate whether nutritional support using omega-3 PUFAs can prevent and manage skeletal muscle mass depletion.

Diagnostic potential of T1ρ and T2 relaxations in assessing the severity of liver fibrosis and necro-inflammation.

PURPOSE: To investigate the utility of T1ρ and T2 relaxations for assessing the severity of liver fibrosis (F stage) and necro-inflammation (A stage) in patients with chronic liver disease (CLD). MATERIALS AND METHODS: We calculated T1ρ and T2 relaxations of the liver parenchyma in 82 patients who underwent liver surgery. F and A stages of enrolled patients were assessed by referring to surgically resected specimens. The relationships between T1ρ or T2 relaxation and F or A stage were assessed using one-way analysis of variance followed by Tukey's multiple comparison test, Spearman's rank correlation test and a receiver operating characteristic analysis. RESULTS: The T1ρ and T2 values of the liver parenchyma were significantly increased as the F and A stages progressed. The T1ρ and T2 values showed significant differences between F0 and F4, between F1 and F4, and between F2 and F4. In addition, T1ρ values showed a significant difference between F0 and F3 as well. The highest diagnostic ability for fibrosis was obtained when differentiating ≥F3 from ≤F2 using T1ρ: the sensitivity was 82.8%, the specificity 79.2% and the area under the curve (AUC) 0.87. The sensitivity and AUC of T1ρ relaxation (46.9% and 0.67) were significantly higher than those of T2 relaxation (29.7% and 0.60) for differentiating ≥A1 from A0. CONCLUSION: T1ρ and T2 relaxations have potential as a biochemical marker for assessing the severity of liver fibrosis and necro-inflammation. T1ρ relaxation may be slightly superior to T2 relaxation in terms of diagnostic ability for liver fibrosis and necro-inflammation.

Differentiating Liver Hemangioma from Metastatic Tumor Using T2-enhanced Spin-echo Imaging with a Time-reversed Gradient-echo Sequence in the Hepatobiliary Phase of Gadoxetic Acid-enhanced MR Imaging.

PURPOSE: To evaluate the utility of T2-enhanced spin-echo imaging using the time-reversed gradient echo sequence (T2FFE imaging) in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI (Gd-EOB-MRI) for differentiating hemangiomas from metastatic tumors. METHODS: A total of 61 patients with 133 liver lesions, including 37 hemangiomas and 96 metastatic tumors, were scanned by Gd-EOB-MRI. Four data sets were independently analyzed by two readers: (1) 3D fat-suppressed T2-weighted imaging (FS-T2WI) alone; (2) the combination of 3D FS-T2WI and T2FFE imaging in the HBP of Gd-EOB-MRI; (3) the combination of 3D FS-T2WI, diffusion-weighted imaging (DWI) with the b-value of 1000 s/mm2 and the apparent diffusion coefficient (ADC); and (4) a dynamic study of Gd-EOB-MRI. After classifying the lesion sizes as ≤ 10 mm or > 10 mm, we conducted a receiver-operating characteristic analysis to compare diagnostic accuracies among the four data sets for differentiating hemangiomas from metastatic tumors. RESULTS: The areas under the curves (AUCs) of the four data sets of two readers were: (1) ≤ 10 mm (0.85 and 0.91) and > 10 mm (0.88 and 0.97), (2) ≤ 10 mm (0.94 and 0.94) and > 10 mm (0.96 and 0.95), (3) ≤ 10 mm (0.90 and 0.87) and > 10 mm (0.89 and 0.95), and (4) ≤ 10 mm (0.62 and 0.67) and > 10 mm (0.76 and 0.71), respectively. Data sets (2) and (3) showed no significant differences in AUCs, but both showed significantly higher AUCs compared to that of (4) regardless of the lesion size (P < 0.05). CONCLUSION: The combination of 3D FS-T2WI and T2FFE imaging in the HBP of Gd-EOB-MRI achieved an accuracy equivalent to that of the combination of 3D FS-T2WI, DWI, and ADC and might be helpful in differentiating hemangiomas from metastatic tumors.

Improvement of Image Quality Using Hybrid Iterative Reconstruction with Noise Power Spectrum Model in Computed Tomography During Hepatic Arteriography.

OBJECTIVES: In CT during hepatic arteriography (CTHA), the addition of a noise power spectrum (NPS) model to conventional hybrid iterative reconstruction (HIR) may improve spatial resolution and reduce image noise. This study aims at assessing the image quality provided by HIR with a NPS model at CTHA. METHODS: This institutional review board-approved retrospective analysis included 26 patients with hepatocellular carcinomas (HCCs) who underwent CTHA. In all acquisitions, images were reconstructed with filtered back projection (FBP), adaptive iterative dose reduction 3D (AIDR), and AIDR enhanced (eAIDR) with the NPS model. Four radiologists analyzed the signal-to-noise ratio (SNR) of HCC nodules and its associated feeding arteries. The radiologists used a semiquantitative scale (-3 to +3) to rate the subjective image quality comparing both the FBP and eAIDR images with the AIDR images. RESULTS: The feeding arteries' attenuation was significantly higher in eAIDR compared to AIDR [514.3 ± 121.4 and 448.3 ± 107.3 Hounsfield units (HU), p < 0.05]. The image noise of eAIDR was significantly lower than that of FBP (15.2 ± 2.2 and 28.5 ± 4.8 HU, p < 0.05) and comparable to that of AIDR. The SNR of feeding arteries on eAIDR was significantly higher than on AIDR (34.1 ± 7.9 and 27.4 ± 6.3, p < 0.05). Subjective assessment scores showed that eAIDR provided better visibility of feeding arteries and overall image quality compared to AIDR (p < 0.05). The HCC nodule visibility was not significantly different among the three reconstructions. CONCLUSION: In CTHA, eAIDR improved the visibility of feeding arteries associated with HCC nodules without compromising nodule detection.

Hemodynamic Alteration in the Liver in Acute Hepatitis: A Quantitative Evaluation Using Computed Tomographic Perfusion.

BACKGROUND/AIM: We aimed to elucidate the hemodynamic alterations in the liver of patients with acute hepatitis (AH) using computed tomography perfusion imaging. PATIENTS AND METHODS: For 14 patients with AH and nine patients with no disease (ND group), we compared the mean arterial blood flow (AF), portal blood flow (PF) and perfusion index (%) [PI=AF/(AF+PF) ×100] of the right and left liver lobes and investigated their relationship with clinical factors. RESULTS: The mean PI of the right lobe in the AH group (30.5±10.0%) was significantly higher than that in the ND group (20.8±9.7%) (p=0.031). For all patients of the AH and ND groups, the PI of the right lobe was increased as the prothrombin time decreased (R=-0.56, p=0.006) and as the prothrombin time-international normalized ratio increased (R=0.48, p=0.02). CONCLUSION: The PI of the right liver lobe may increase in AH and may be a predictive parameter for the severity of hepatic failure.

Radiology- and gene-based risk stratification in small renal cell carcinoma: A preliminary study.

PURPOSE: Most small renal cell carcinomas (small RCCs) will remain indolent after detection, but some stage I RCCs still metastasize. There are no risk-stratification imaging factors that could be used to identify poor-prognosis patients based on genomic profiling. Here, we evaluated the relationships between imaging parameters and RNA expressions in small RCC and attempted to identify imaging factors that could be used as effective biomarkers. METHODS: We acquired biopsy specimens of 18 clear cell carcinomas that had undergone perfusion CT (pCT) and MRI between April 2018 and March 2019. We performed RNA sequencing, assessed RNA expressions, and calculated each tumor's cell-cycle progression (CCP) score, which has prognostic value in predicting metastatic progression. We classified the tumors into two groups: clear cell type A (ccA) and type B (ccB). CcA has better survival compared to ccB. We evaluated the following characteristics of each tumor: tumor size, presence of pseudocapsule, and fat. We used the pCT and MRI to measure each tumor's volume transfer constant (Ktrans), rate constant (Kep), extracellular extravascular volume fraction (VE), fractional plasma volume (VP), and apparent diffusion coefficient (ADC). The correlations between these small RCC imaging parameters and the tumor size and RNA expressions were determined. RESULTS: The tumor size was significantly correlated with Kep and inversely correlated with VE, VP, ADC, and hallmark angiogenesis. The CCP score was significantly inversely correlated with Ktrans and Kep. The ccA tumors tended to show a pseudocapsule on MRI. CONCLUSION: Tumor size was correlated with low perfusion, but not with prognostic factors based on genomic profiling. Imaging parameters (e.g., Ktrans and Kep) and tumor characteristics (e.g., pseudocapsule) may enable gene-based risk stratification in small RCC.

Cryoablation for Secondary Renal Cell Carcinoma After Surgical Nephrectomy.

PURPOSE: To retrospectively evaluate the clinical outcomes of cryoablation for secondary renal cell carcinoma for patients with a history of nephrectomy for initial renal cell carcinoma. MATERIALS AND METHODS: Thirty patients with 40 renal tumors who had undergone a nephrectomy for initial renal cell carcinoma and cryoablation for renal cell carcinoma as a secondary treatment during the period from April 2014 to December 2018 at a single center institution were enrolled. The patients' overall survival, local control, relapse-free survival, change of renal function, and complications were evaluated. The clinical factors of relapse-free survival were also evaluated. RESULTS: The 5 year overall survival rate was 94.5%, the 5 year local control rate was 89.3%, and the 5 year relapse-free survival rate (RFSR) was 56.3%. There was an average reduction in renal function of 8.5% after 1 year, and > grade 3 complications occurred in only one case. The RFSR in the patients whose initial stage was T3 was 0%, significantly lower than the 70.4% RFSR in the patients whose initial stage was T1 or T2. CONCLUSION: Cryoablation for secondary renal cell carcinoma after nephrectomy was safe and provided good local control with preserved renal function. However, the indications for cryoablation should be carefully considered for patients with T3-stage initial renal cell carcinoma, because of the high risk of relapse. LEVEL OF EVIDENCE: III.

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.

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.

Amide proton transfer imaging for differentiating benign ovarian cystic lesions: Potential of first time right.

PURPOSE: To investigate whether amide proton transfer (APT) imaging is useful to differentiate benign ovarian cystic lesions. MATERIALS AND METHODS: This prospective study enrolled a total of 19 lesions in 18 patients with benign ovarian cystic lesion: serous cystadenoma (SCA), n = 4; mucinous cystadenoma (MCA), n = 9; or functional cyst (FC), n = 6. APT imaging was performed with three different presaturation pulse durations: 0.5, 1.0 and 2.0 s. APT signal was defined as magnetization transfer ratio asymmetry at 3.5 ppm. The SI ratios of cyst to muscle calculated on T1- and T2-weighted images were defined as T1- and T2-ratios. Apparent diffusion coefficient (ADC) maps were also generated. We compared the three cystic lesion groups' APT signals, T1-ratio, T2-ratio, and ADC. RESULTS: When using 2.0 s of presaturation, the APT signals were 1.41 ±â€¯0.71% in SCA, 5.15 ±â€¯1.92% in MCA and 8.52 ±â€¯1.17% in FC. Significant differences were observed between SCA and MCA (p < .01) and MCA and FC (p < .05), as well as between SCA and FC (P <  .0001). When 1.0 s presaturation pulse was used, similar results were obtained. On the other hand, ADC value shows significance only between SCA (2.91±0.03×10-3 mm2/s) and MCA (2.59 ±â€¯0.49 × 10-3 mm2/s, p < .05). Further, there was no significant difference in the T1-ratio, T2-ratio among the three groups. CONCLUSIONS: APT imaging might be useful for the non-invasive diagnosis of benign ovarian cystic lesions. With the use of the longer presaturation pulse as possible, APT imaging may provide an early and correct diagnosis of ovarian cystic lesions without additional follow-up studies.