Usefulness of T2*-weighted MRI in the detection of adnexal torsion.

BACKGROUND: The usefulness of T2*-weighted (T2*W) imaging for the detection of adnexal torsion has yet to be determined. PURPOSE: To assess the usefulness of T2*W imaging for detecting and differentiating adnexal torsion. MATERIAL AND METHODS: Eight patients with eight ovaries with torsion and 44 patients with 72 ovaries without torsion were included in this study. All patients underwent 1.5-T magnetic resonance imaging (MRI) including T2*W images. The frequency and distribution of hypointensity on T2*W images were compared between ovaries with torsion and ovaries without torsion. RESULTS: Hypointensity on T2*W images was significantly more frequent in ovaries with torsion than in ovaries without torsion (75% vs. 36%; P < 0.05). Among patients with hypointensity on T2*W images, the frequency of diffuse hypointensity was significantly higher in ovaries with torsion than in ovaries without torsion (83% vs. 0%; P < 0.01); whereas the frequency of focal hypointensity was significantly lower in ovaries with torsion than in ovaries without torsion (17% vs. 100%; P < 0.01). CONCLUSION: The presence and distribution of hypointensity on T2*W images may play a supplementary role in the detection of adnexal torsion.

A multi-institutional survey of interventional radiology for type II endoleaks after endovascular aortic repair: questionnaire results from the Japanese Society of Endoluminal Metallic Stents and Grafts in Japan.

PURPOSE: To investigate the current status of interventional radiology (IR) procedures for a type II endoleak (T2EL) in Japan, and to identify the technical aspects that affect treatment results. MATERIALS AND METHODS: A retrospective survey was conducted by distributing questionnaires to 25 institutions. The eligibility criteria were endovascular aortic repair (EVAR) performed using commercial stent grafts and IR performed for T2EL between January 2007 and December 2013. Technical success was defined as disappearance of the EL on digital subtraction angiography immediately after embolization, and imaging success was defined as no EL on contrast-enhanced computed tomography within 6 months. Statistical comparisons of the number of involved branches, embolization level, embolic material, and changes in aneurysm size were made between the imaging success and imaging failure groups. The technical and imaging success rates were also compared between the initial therapy and repeat groups. RESULTS: A total of 166 cases were investigated. Initial therapy was performed in 147 cases (88.6 %), with repeat therapy in 19 cases (11.4 %). Transcatheter arterial embolization (TAE) was used most frequently, in 161 cases (97 %), with direct puncture (DP) used in 5 cases (3 %). Both coil embolization for the branches and NBCA embolization for the sac were frequently chosen. The technical success rate was 83.2 % (TAE group), and the imaging success rate was 46.5 % (TAE + DP groups). Branch + sac embolization was performed more frequently in the imaging success group. There was no significant difference in the number of involved branches or embolic material between the imaging success and imaging failure groups. Enlargement of the aneurysm was more frequently seen in the imaging failure group. There were no significant differences in the technical success and imaging success rates between the initial therapy and repeat groups. CONCLUSION: This is the first report of a multi-institutional questionnaire survey of IR procedures for T2EL after EVAR in Japan that was conducted to determine the current status. Enlargement of aneurysm size after embolization was more frequently seen in the imaging failure group. It is important to embolize both branch and sac to achieve imaging success, regardless of embolic material. Long-term outcomes need to be investigated.

Relationship between diverse patient body size- and image acquisition-related factors, and quantitative and qualitative image quality in coronary computed tomography angiography: a multicenter observational study.

PURPOSE: We investigated the effects of patient- and image acquisition-related factors on the image quality in coronary CT angiography (CCTA). MATERIALS AND METHODS: We enrolled 1197 patients (728 men; 65 ± 12 years). All underwent CCTA under the routine scan protocol in 23 participating hospitals. The subjective image quality (3-point Likert scale: excellent, good, and poor) and the attenuation of the left and right coronary artery (LCA, RCA) were recorded; the effects of patient and image acquisition-related factors on vascular attenuation were then compared. RESULTS: The mean LCA attenuation was 515.2 ± 65.8 (excellent), 401.4 ± 63.4 (good), and 319.5 ± 47.6 HU (poor). The corresponding RCA attenuation was 496.6 ± 67.6, 390.5 ± 58.5, and 308.5 ± 50.7 HU, respectively. Univariate analysis revealed significant associations between sufficient coronary attenuation (> 400 HU) and the age, gender, body surface area (BSA), number of detectors, contrast synchronization, scan mode, and the fractional contrast dose. Multivariate analysis revealed that the bolus tracking method, prospective electrocardiogram gating, and fractional contrast dose were significantly associated with sufficient coronary enhancement. CONCLUSION: BSA and fractional contrast dose are the most important patient- and image acquisition-related factors for sufficient coronary attenuation in CCTA.

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.

Minimally Required Iodine Dose for the Detection of Hypervascular Hepatocellular Carcinoma on 80-kVp CT.

OBJECTIVE: The objective of our study was to determine the iodine dose per unit of body weight (BW) or body surface area (BSA) that is minimally required to detect hypervascular hepatocellular carcinoma (HCC) on 80-kVp CT. SUBJECTS AND METHODS: One hundred eleven patients (78 men and 33 women; mean age, 68 years; age range, 43-85 years) with chronic hepatitis were randomized into three groups with different iodine loads (0.5, 0.4, and 0.3 g I/kg BW) and underwent contrast-enhanced CT at 80 kVp. Enhancement of the liver and of hypervascular HCCs was quantitatively and qualitatively assessed on hepatic arterial, portal venous, and equilibrium phase images and compared between the groups. Values for iodine dose per unit of BSA (g I/m(2)) were also computed and analyzed. RESULTS: No significant differences in the contrast-to-noise ratio (CNR) of hypervascular HCCs in any phase were found between the groups (p = 0.34-0.99). In the portal venous phase, the mean increase in hepatic contrast enhancement (ΔHU) of the 0.5 g I/kg group (80.3 HU) was higher than those of the 0.4 g I/kg (63.4 HU) and 0.3 g I/kg (53.3 HU) groups (p < 0.001). Linear correlation equations for the increase in hepatic contrast enhancement were as follows: ΔHU = 5.9 + 150.0 × IL(BW) (r = 0.69, p < 0.001), where IL(BW) is the iodine load per unit of BW (g I/kg), and ΔHU = 13.0 + 3.68 × IL(BSA) (r = 0.66, p < 0.001), where IL(BSA) is the iodine load pre unit of BSA (g I/m(2)). CONCLUSION: The minimal iodine dose required to achieve a tumor-to-liver CNR that is acceptable for the detection of hypervascular HCCs on 80-kVp CT was 0.3 g I/kg BW or 11.0 g I/m(2) BSA.

The Optimal Body Size Index with Which to Determine Iodine Dose for Hepatic Dynamic CT: A Prospective Multicenter Study.

PURPOSE: To identify the body size parameter that exhibits the best correlation with aortic and hepatic enhancement at hepatic dynamic computed tomography (CT) in a large patient population enrolled in a multicenter study. MATERIALS AND METHODS: This prospective study was approved by the ethics committee of each of the 31 participating institutions where 1342 patients were enrolled between April 2012 and September 2013. All patients provided either written or oral informed consent. All patients underwent hepatic dynamic CT, which included preenhanced, hepatic arterial phase (HAP), and portal venous phase (PVP) scanning, performed with the routine scanning protocol of each institution. Changes in CT number (in Hounsfield units) per gram of iodine in the aorta (eA/I) and liver (eL/I) during HAP and PVP scanning were recorded for each patient. Hierarchical multivariate linear regression analysis was performed in which the outcome variable was either eA/I or eL/I; the independent variables were age, sex, one body size parameter (height, body weight, body mass index, lean body weight [LBW], or body surface area), and liver function (aspartate aminotransferase, albumin, and total bilirubin levels). A two-level hierarchical model in which patients were level 1 and the institution was level 2 was used. RESULTS: Hierarchical multivariate linear regression analysis revealed that in the population not stratified by sex, body size was significantly correlated with eA/I and eL/I (P < .001) and that LBW exhibited the strongest correlation with eA/I and eL/I (r = -0.561 and r = -0.601, respectively). Sex-stratified analysis showed that LBW was more strongly correlated with eA/I and eL/I in women (r = -0.779 and r = -0.948, respectively) than in men (r = -0.500 and r = -0.494, respectively) or in the nonstratified total population. CONCLUSION: Among body size parameters, LBW exhibited the strongest correlation with aortic and hepatic enhancement, especially in women.

Assessment of uterine enhancement rate after abdominal radical trachelectomy using dynamic contrast-enhanced magnetic resonance imaging.

PURPOSE: The purpose of this study was to assess uterine enhancement rate after abdominal radical trachelectomy (ART) using dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging. METHODS: Ten patients with early uterine cervical cancer, who were treated by ART, were included in this study. Each patient underwent DCE MR imaging using a 3 T unit to assess uterine enhancement rate at three times (before surgery and 1 and 3 months after surgery). The radiologist calculated mean signal intensities of the anterior and posterior myometrium and also measured the signal intensities of the urine in the bladder on the same image, which was expressed as the myometrium-to-urine signal intensity ratio. In the time-intensity ratio curve, enhancement parameters (peak signal intensity ratio and peak time) of the uterine body were compared across the three MR examinations. RESULTS: The peak signal intensity ratio was 6.96 ± 0.98 on MR examinations before surgery, 6.14 ± 0.81 1 month after surgery, and 6.26 ± 0.63 3 months after surgery (p = 0.069). The peak time was 57.6 ± 3.4 s on MR examinations before surgery, 56.4 ± 4.4 s 1 month after surgery, and 53.2 ± 8.0 s 3 months after surgery (p = 0.304). No significant differences were found in either the peak signal intensity ratio or peak time across the three MR examinations. CONCLUSIONS: That no significant decrease of uterine enhancement rate was found after surgery suggests the uterine function and fertility may be preserved after ART.

Findings in pancreatic MRI associated with pancreatic fibrosis and HbA1c values.

PURPOSE: To evaluate the diagnostic performance of noncontrast-enhanced magnetic resonance imaging (MRI) to grade pancreatic fibrosis and to assess hemoglobin (Hb) A1c values. MATERIALS AND METHODS: Twenty-nine consecutive patients with pancreatic or biliary malignancy who underwent pancreatectomy were evaluated. Patients were classified into three groups: HbA1c < 5.7 (group 1), 5.7 ≤ HbA1c < 6.5 (group 2), and HbA1c ≥ 6.5 (group 3). MRI of the pancreas was performed using a 1.5T MR system. The pancreas-to-muscle signal intensity ratio (SIR) on in- and opposed-phase T1 -, T2 -, and diffusion-weighted images, as well as the apparent diffusion coefficient were calculated. MRI measurements, degrees of pancreatic fibrosis, and HbA1c values were compared using multiple regression analysis and Kruskal-Wallis test. RESULTS: The pancreatic fibrosis grade was negatively correlated with the SIR on in-phase T1 -weighted images (r = -0.67, P = 0.0002). The pancreatic fibrosis grade and HbA1c value were negatively correlated with the SIR on opposed-phase T1 -weighted images (r = -0.47, P = 0.019 and r = -0.51, P = 0.0089, respectively). SIRs on in- and opposed-phase T1 -weighted images were significantly lower in group 3 than in groups 1 and 2 (P < 0.05). CONCLUSION: The pancreas-to-muscle SIRs on in- and opposed-phase T1 -weighted images could be a potential biomarker for pancreatic fibrosis and elevated HbA1c values.

MR imaging findings of pilomatricomas: a radiological-pathological correlation.

BACKGROUND: Magnetic resonance imaging (MRI) findings of pilomatricomas have yet to be determined. PURPOSE: To assess the correlation between MRI and pathological findings of pilomatricomas. MATERIAL AND METHODS: MR images were obtained on patients with histologically proven pilomatricomas using a 1.5-T MR scanner. The images were retrospectively reviewed for size, signal intensity compared with skeletal muscles, and enhancement patterns. Furthermore, we assessed the presence of a reticular appearance, a ring-like appearance, and peritumoral fat stranding. RESULTS: We included 11 consecutive patients with 12 histologically proven pilomatricomas (3 boys/men, 8 girls/women; age range, 4-76 years; mean age, 20 years; median age, 14 years). The tumors were located in the head and neck (n = 6), upper extremities (n = 5), and lower extremities (n = 1). The maximum tumor diameter was in the range of 7-32 mm (mean, 16.5 mm). On T2-weighted (T2W) images, five tumors showed homogeneous hypointensity, whereas six showed reticular hyperintensity and one showed cystic hyperintensity. On fat-suppressed T2W images, nine tumors showed reticular hyperintensity, eight showed ring-like hyperintensity, and five showed peritumoral fat stranding. On fat-suppressed gadolinium-enhanced T1-weighted (T1W) images, one tumor showed no enhancement, whereas three showed reticular enhancement and five showed ring-like enhancement. Histologically, edematous and fibrous stroma was observed in 10 tumors, tumor capsules in 11, and inflammatory cell infiltration of the peritumoral fat tissue in nine. CONCLUSION: MRI features of pilomatricomas included reticular and ring-like hyperintensities on fat-suppressed T2W images and reticular and ring-like enhancement on fat-suppressed gadolinium-enhanced T1W images.

Usefulness of the dual energy field-in-field technique in breast tangential radiotherapy.

PURPOSE: In the field-in-field (FIF) technique in breast tangential radiotherapy, the energy of the subfield is usually the same as the energy of the main field. However, some studies have applied 10-18 MV to subfields in patients with large breasts. We compared two FIF plans in 66 breast cancer patients: in one, the energy of the subfield was the same as that of the main field (the mono energy plan); in the other, it was higher (the dual energy plan). MATERIALS AND METHODS: The photon energy of the subfield was 6 MV in the mono energy plan and 10 MV in the dual energy plan. The percentage of the planning target volume (PTV) receiving at least 105, 100, and 95% of the prescribed dose (V105, V100, and V95, respectively) was calculated, as were the maximum and mean doses delivered to the PTV (Dmax and Dmean, respectively). Clinical target volumes (CTVs) and the thickness of the breast between the chest wall and skin surface at the level of the nipple were measured. RESULTS: V95% was significantly higher in the dual energy plan than in the mono energy plan in patients with CTVs or breast thickness in the highest quartile. There were no significant differences in the other parameters of the two plans in these patients. CONCLUSION: These findings demonstrate the usefulness of the dual energy FIF technique in patients with large breasts receiving breast tangential radiotherapy.

Safe use of iodinated and gadolinium-based contrast media in current practice in Japan: a questionnaire survey.

PURPOSE: To help establish consensus on the safe use of contrast media in Japan. MATERIALS AND METHODS: Questionnaires were sent to accredited teaching hospitals with radiology residency programs. RESULTS: The reply rate was 45.4% (329/724). For contrast-induced nephropathy (CIN), chronic and acute kidney diseases were considered a risk factor in 96.7 and 93.6%, respectively, and dehydration in 73.9%. As preventive actions, intravenous hydration (89.1%) and reduction of iodinated contrast media dose (86.9%) were commonly performed. For nephrogenic systemic fibrosis (NSF), chronic and acute kidney diseases were considered risk factors in 98.5 and 90.6%, respectively, but use of unstable gadolinium-based contrast media was considered a risk factor in only 55.6%. A renal function test was always (63.5% in iodinated; 65.7% in gadolinium) or almost always (23.1; 19.8%) performed, and estimated glomerular filtration rate (eGFR) was the parameter most frequently used (80.8; 82.6%). For the patients with risk factors for acute adverse reaction (AAR), steroid premedication or/and change of contrast medium were frequent preventive actions, but intravenous steroid administration immediately before contrast media use was still performed. CONCLUSION: Our questionnaire survey revealed that preventive actions against CIN were properly performed based on patients' eGFR. Preventive actions against NSF and AAR still lacked consensus.

F-18 FDG uptake on positron emission tomography as a predictor for lymphovascular invasion in patients with lung adenocarcinoma.

PURPOSE: To evaluate the contributory value of Fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography/computed tomography (PET/CT) in the prediction of lymphovascular tumor invasion in patients with lung adenocarcinoma. MATERIALS AND METHODS: We evaluated F-18 FDG-PET/CT images in 84 patients with histopathologically proven lung adenocarcinoma (37 men and 47 women, age range 39-83 years, mean age 67.0 ± 8.9 years). The maximum standardized uptake values (SUVmax) of the carcinomas were measured from the PET images. The Mann-Whitney U test was conducted to compare the median SUVmax between the tumor groups with and without lymphovascular invasion. In the subgroup patients with no lymph-node metastasis, we also compared the median SUVmax between the tumor groups with and without lymphatic invasion. RESULTS: The tumors with lymphovascular invasion had a significantly (P < 0.0001) greater median SUVmax than those without invasion. In the subgroup patients with no lymph-node metastasis, the median SUVmax was higher in tumors with lymphatic invasion than those without (P = 0.0004). The sensitivity, specificity, and area under the receiver operating characteristic curve for the detection of tumors with lymphovascular invasion were 89, 75 %, and 0.82, respectively, with a cutoff SUVmax value of 2.32. CONCLUSION: The SUVmax of lung adenocarcinoma is a potential imaging biomarker for predicting tumor lymphovascular invasion.

Diffusion kurtosis imaging of the pancreas for the assessment of HbA1c levels.

PURPOSE: To evaluate the feasibility of diffusion kurtosis (DK) imaging of the pancreas for the assessment of hemoglobin (Hb) A1c values. MATERIALS AND METHODS: Our Institutional Review Board approved this prospective study and written informed consent was obtained. In all, 102 consecutive patients with suspected pancreatic disease underwent magnetic resonance imaging (MRI), including DK imaging. Patients were classified into three groups according to American Diabetes Association criteria: HbA1c < 5.7% (group 1), 5.7% ≤ HbA1c < 6.5% (group 2), and HbA1c ≥ 6.5% (group 3). Mean kurtosis (MK) and apparent diffusion coefficient (ADC) of pancreatic parenchyma were computed. MRI measurements and HbA1c values were then compared. RESULTS: HbA1c values positively correlated with MK (r = 0.66, P < 0.0001). Group 3 was significantly (P < 0.05) higher (P < 0.05) in MK than groups 1 and 2. The sensitivity, specificity, and area under the ROC curve of the MK for the detection of group 3 were 90%, 88%, and 0.92, respectively. CONCLUSION: The MK measurement on DK imaging of the pancreas could be a potential biomarker for assessing HbA1c level.

Evaluation of the field-in-field technique with lung blocks for breast tangential radiotherapy.

Several studies have reported the advantages of the field-in-field (FIF) technique in breast radiotherapy, including dose reduction in the lungs by using lung field blocks. We evaluated the FIF technique with lung blocks for breast tangential radiotherapy. Sixteen patients underwent free breathing (FB) computed tomography (CT), followed by two CT procedures performed during breath hold after light inhalation (IN) and light exhalation (EX). Three radiotherapy plans were created using the FIF technique based on the FB-CT images: one without lung blocks (LB0) and two with lung blocks whose monitor units (MUs) were 5 (LB5) and 10 (LB10), respectively. These plans were copied to the IN-CT and EX-CT images. V20Gy, V30Gy, and V40Gy of the ipsilateral lung and V100%, V95%, and the mean dose (Dmean) to the planning target volume (PTV) were analyzed. The extent of changes in these parameters on the IN-plan and EX-plan compared with the FB-plan was evaluated. V20Gy, V30Gy, and V40Gy were significantly smaller for FB-LB5 and FB-LB10 than for FB-LB0; similar results were obtained for the IN-plan and EX-plan. V100%, V95%, and Dmean were also significant smaller for FB-LB5 and FB-LB10 than for FB-LB0. The extent of changes in V20Gy, V30Gy, and V40Gy on the IN-plan and EX-plan compared with the FB-plan was not statistically significant. Lung blocks were useful for dose reduction in the lung and a simultaneous PTV decrease. This technique should not be applied in the general population.

Magnetic resonance imaging of uterine fibroids: a preliminary investigation into the usefulness of 3D-rendered images for surgical planning.

PURPOSE: This study aimed to assess the efficacy of 3D surface-rendered (SR) magnetic resonance (MR) images for surgical planning of uterine fibroids. METHODS: Ten patients with uterine fibroids underwent 3D volume isotropic turbo spin-echo acquisition (VISTA) sequences in sagittal planes. SR images showing the uterine body, endometrium, and fibroids were extracted from the raw MR data. The preoperative assessment for fertility-preserving fibroid enucleation was independently performed by two gynecologists using 2D sagittal and 3D SR images separately. RESULTS: The required interpretation times [second] for sagittal versus SR images were 19.7 ± 9.5 versus 10.4 ± 5.1 for observer 1 (p < 0.05) and 47.5 ± 12.3 versus 19.7 ± 9.5 for observer 2 (p < 0.01). The accuracy rates of the planned surgical procedures from sagittal versus SR images were 50 versus 70% for observer 1 and 70 versus 70% for observer 2. The accuracy rates of the numbers of fibroids to be removed from sagittal versus SR images were 70 versus 80% for observer 1 and 70 versus 80% for observer 2. CONCLUSION: Compared with sagittal images, SR images could significantly reduce the time required for surgical planning of uterine fibroids without sacrificing the accuracy of the preoperative assessment.

Differentiation of extranodal non-Hodgkins lymphoma from squamous cell carcinoma of the maxillary sinus: a multimodality imaging approach.

This study aimed to assess the efficacy of a multimodality imaging approach for differentiating between primary extranodal non-Hodgkin's lymphoma (NHL) and squamous cell carcinoma (SCC) of the maxillary sinus. Twelve NHLs and 29 SCCs of the maxillary sinus were included. CT findings, MR signal intensities, apparent diffusion coefficients (ADCs), and maximum standardized uptake values (SUVmax) were correlated with two pathologies. On CT, permeative growth frequency was greater among NHLs than among SCCs (50 % vs. 10 %; p < 0.01), whereas destructive growth frequency was greater among SCCs than among NHLs (83 % vs. 33 %; p < 0.01). On CT, remaining sinus wall within the tumor was more frequent with NHLs than with SCCs (92 % vs. 34 %; p < 0.01), whereas intratumoral necrosis was more frequent with SCCs than with NHLs (86 % vs. 17 %; p < 0.01). ADCs were lower for NHLs than for SCCs (0.61 vs. 0.95 × 10(-3) mm(2)/s; p < 0.01). No significant differences in MR signal intensities and SUVmax were observed. Tumor growth pattern, remaining sinus wall within the tumor, and intratumoral necrosis were useful CT findings for differentiating between NHLs and SCCs. ADC measurements could assist the differentiation of NHL from SCC.

Perfusion imaging of parotid gland tumours: usefulness of arterial spin labeling for differentiating Warthin's tumours.

OBJECTIVE: To assess prospectively the efficacy of arterial spin labelling (ASL) against conventional and diffusion-weighted (DW) MR imaging for differentiating parotid gland tumours. METHODS: We included 10 pleomorphic adenomas, 12 Warthin's tumours, and nine malignant tumours of the parotid glands. Only tumours larger than 10 mm were included in this study. All parotid gland tumours underwent T1-weighted, T2-weighted, DW, and ASL imaging. Tumour-to-parotid gland signal intensity ratios (SIRs) and apparent diffusion coefficients (ADCs) of solid components were correlated with these pathologies. RESULTS: SIRs on T2-weighted images and ADCs were higher in pleomorphic adenomas than in Warthin's tumours (p < .01) and malignant tumours (p < .01). SIRs on ASL were higher in Warthin's tumours than in pleomorphic adenomas (p < .01) and malignant tumours (p < .05). Az value of SIRs on ASL for differentiating Warthin's tumours from the other pathologies was 0.982. The sensitivity, specificity, and accuracy of SIRs on ASL for the diagnosis of Warthin's tumours at an optimal SIR threshold of over 8.70 were 91.7%, 94.7%, and 93.5%, respectively. CONCLUSIONS: ASL with SIR measurements could non-invasively evaluate tumour blood flow of parotid gland tumours and differentiate Warthin's tumours from pleomorphic adenomas and malignant tumours. KEY POINTS: • ASL non-invasively evaluates tumour blood flow of parotid gland tumours • ASL differentiates Warthin's tumours from pleomorphic adenomas and malignant tumours • ASL cannot differentiate between pleomorphic adenomas and malignant tumours.

18-F fluorodeoxyglucose uptake in positron emission tomography as a pathological grade predictor for renal clear cell carcinomas.

OBJECTIVES: To evaluate the usefulness of Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18-F FDG-PET/CT) in the prediction of Fuhrman pathological grades of renal clear cell carcinoma (cRCC). METHODS: This retrospective study was approved by our institutional review board, and written informed consent was waived. Thirty-one patients with pathologically proven cRCC underwent 18-F FDG-PET/CT for tumour staging. Maximum standardized uptake value of cRCC (tumour SUVmax) and mean SUV of the liver and spleen (liver and spleen SUVmean) were measured by two independent observers. Tumour SUVmax, tumour-to-liver SUV ratio, and tumour-to-spleen SUV ratio were correlated with the pathological grades. RESULTS: Logistic analysis demonstrated that only the tumour-to-liver SUV ratio was a significant parameter for differentiating high-grade (Fuhrman grades 3 and 4) tumours from low-grade (Fuhrman grades 1 and 2) tumours (P = 0.007 and 0.010 for observers 1 and 2, respectively). Sensitivity, specificity, and positive and negative predictive values for detecting tumours of Fuhrman grades 3 and 4 were 64, 100, 100, and 77%, respectively, for observer 1, and 79, 88, 85, and 83%, respectively, for observer 2. CONCLUSIONS: The tumour-to-liver SUV ratio with 18-F FDG-PET/CT appeared to be a valuable imaging biomarker in the prediction of high-grade cRCC. KEY POINTS: • Tumour SUV max was correlated with the Fuhrman grades. • High-grade tumours have significantly higher SUV max than low-grade tumours. • Tumour-to-liver SUV ratio is useful in the prediction of high-grade cRCC.

Diffusion kurtosis imaging to assess response to treatment in hypervascular hepatocellular carcinoma.

OBJECTIVE: The objective of our study was to compare diffusion kurtosis imaging (DKI) with conventional diffusion-weighted imaging (DWI) for assessing the response to treatment in hypervascular hepatocellular carcinoma (HCC). SUBJECTS AND METHODS: Sixty-two consecutive patients with treated or untreated hypervascular HCC underwent MRI of the liver including DKI (b values of 0, 100, 500, 1000, 1500, and 2000 s/mm(2)). The mean kurtosis (MK) and apparent diffusion coefficient (ADC) values of the hepatic parenchyma and of the HCCs were computed. The detectability of viable HCC based on MK and ADC values was compared. We also assessed the correlation between Child-Pugh grades and MK or ADC values. RESULTS: For a total of 112 HCC nodules (viable, n = 63; nonviable, n = 49), the MK value was significantly higher for the viable group (mean ± SD, 0.81 ± 0.11) than for the non-viable group (0.57 ± 0.11) (p < 0.001). The mean ADC value was significantly lower for the viable group (1.44 ± 0.42 × 10(-3) mm(2)/s) than for the nonviable group (1.94 ± 0.52 × 10(-3) mm(2)/s) (p < 0.001). The sensitivity, specificity, and AUC of the ROC curve for the assessment of HCC viability were greater (p < 0.001) using MK (85.7%, 98.0%, and 0.95, respectively; cutoff value = 0.710) than using ADC (79.6%, 68.3%, and 0.77, respectively; cutoff value = 1.535 × 10(-3) mm(2)/s). Although the ADC of hepatic parenchyma was lower in patients with Child-Pugh grade B or C disease than in those with grade A disease (p = 0.02), no significant difference in MK (p = 0.45) was found among the Child-Pugh grades. CONCLUSION: DKI can be a new option for the assessment of posttherapeutic response in HCC.