Quantification of Cisplatin Using a Modified 3-Material Decomposition Algorithm at Third-Generation Dual-Source Dual-Energy Computed Tomography: An Experimental Study.

OBJECTIVE: The aim of this study was to assess the ability of third-generation dual-source dual-energy computed tomography to quantify cisplatin concentration using a 3-material decomposition algorithm in an experimental phantom. MATERIALS AND METHODS: Fifteen agarose-based phantoms containing various concentrations of iodine (0, 1.0, 2.0 mg I/mL) and cisplatin (0, 0.5, 1.0, 2.0, 3.0 mg Pt/mL) were scanned using third-generation dual-source dual-energy computed tomography at 80 kV and 150 kV with tin prefiltration. A cisplatin map was generated using the cisplatin-specific 3-material decomposition algorithm to differentiate cisplatin from iodine and agar. The computed tomography (CT) values at 80 kV, 150 kV, mixed 120 kV, and the cisplatin map were measured. Interobserver variabilities for the CT measurements on the cisplatin map were assessed using interclass correlation coefficients. Correlation between the CT values and titrated cisplatin concentrations was correlated using Spearman rank correlation analysis. To assess the influence of iodine, linear regression lines for the CT values on the cisplatin map and titrated cisplatin concentrations were compared using an analysis of covariance. RESULTS: Interobserver agreement revealed almost perfect agreements (interclass correlation coefficients = 0.941-0.995). Significant and excellent positive correlations were observed between the CT values on the cisplatin map and titrated cisplatin concentrations (ρ = 0.980, P < 0.001 for all). The cisplatin map could identify the lowest cisplatin concentration of 0.5 mg Pt/mL in the presence of iodine. The iodine concentration had no significant effect on the CT measurements on the cisplatin map (P = 0.297, adjusted R = 0.993). CONCLUSIONS: The cisplatin map generated from the 3-material decomposition algorithm allows quantification of a cisplatin concentration in an experimental phantom, independent of co-present iodine.

Dual-energy computed tomography for non-invasive staging of liver fibrosis: Accuracy of iodine density measurements from contrast-enhanced data.

AIM: To investigate whether iodine density measurements from contrast-enhanced dual-energy computed tomography (CT) data can non-invasively stage liver fibrosis. METHODS: This single-center, prospective study was approved by our IRB with written informed consent. Forty-seven consecutive patients (26 men and 21 women; mean age, 63.1 years) with chronic liver disease underwent contrast-enhanced dual-energy CT of the liver (non-contrast, arterial, portal venous, and equilibrium phase images), followed by liver biopsy. Iodine density of liver and aorta were obtained by two independent observers. Iodine uptake of the liver (Δ Liver), representing the difference in iodine density between equilibrium phase and non-contrast images, was calculated and normalized by aorta (Δ Liver/Aorta). We accounted for contrast agent distribution volume by using hematocrit level. Accuracy of iodine density measurements for staging liver fibrosis was assessed by using receiver operating characteristic (ROC) curves. Multivariate linear regression analysis was used to assess the impact of independent variables (liver fibrosis stage and patient-related confounders) on iodine uptake. RESULTS: The Δ Liver/Aorta significantly increased and moderately correlated with METAVIR liver fibrosis stage (ρ = 0.645, P < 0.001). Areas under the ROC curve ranged from 0.795 to 0.855 for discriminating each liver fibrosis score (≥F1-F4). METAVIR fibrosis stage was the most significant independent factor associated with Δ Liver (P = 0.005) and Δ Liver/Aorta (P < 0.001). CONCLUSION: Hepatic extracellular volume fraction with contrast-enhanced dual-energy CT can non-invasively stage liver fibrosis in chronic liver diseases. This technique could prove useful for monitoring disease progression and treatment response, potentially reducing the need for liver biopsy.

A novel scoring system for predicting adherent placenta in women with placenta previa.

INTRODUCTION: Placenta previa (PP) is one of the most significant risk factors for adherent placenta (AP). The aim of this study was to evaluate the diagnostic efficacy of a novel scoring system for predicting AP in pregnant women with PP. METHODS: This prospective cohort study enrolled 175 women with PP. The placenta previa with adherent placenta score (PPAP score) is composed of 2 categories: (1) past history of cesarean section (CS), surgical abortion, and/or uterine surgery; and (2) ultrasonography and magnetic resonance imaging findings. Each category is graded as 0, 1, 2, or 4 points, yielding a total score between 0 and 24. When women with PP had PPAP score ≥8, they were considered to be at a high risk for AP and received placement of preoperative internal iliac artery occlusion balloon catheters. If they were found to have AP during CS, they underwent hysterectomy or placenta removal using advanced bipolar with balloon catheter occlusion. The predictive accuracy of PPAP score was evaluated. RESULTS: In total, 23 of the 175 women with PP were diagnosed as having AP, histopathologically or clinically. Twenty-one of 24 women with PPAP score ≥8 had AP, whereas two of 151 women with PPAP score <8 had AP. The scoring system yielded 91.3% sensitivity, 98.0% specificity, 87.5% positive predictive value, and 98.7% negative predictive value for predicting AP in women with PP. DISCUSSION: This prospective study demonstrated that PPAP scoring system may be useful for predicting AP in women with PP.

Focal Myocardial Damage in Cardiac Sarcoidosis Characterized by Strain Analysis on Magnetic Resonance Tagged Imaging in Comparison with Fluorodeoxyglucose Positron Emission Tomography Accumulation and Magnetic Resonance Late Gadolinium Enhancement.

OBJECTIVE: The aims of this study were to characterize focal myocardial damage of cardiac sarcoidosis by strain analysis and to compare it with late gadolinium enhancement (LGE) and fluorodeoxyglucose (FDG) positron emission tomography. METHODS: We reviewed 208 segments from 13 cardiac sarcoidosis patients and measured the circumferential strain (Ecc) and the strain change per second (Ecc rate). The mean Ecc and Ecc rate values were compared between the FDG(+) and FDG(-), and the LGE(+) and LGE(-) segments using Welch's t test. RESULTS: The peak and max Ecc rates were better in the LGE(-) segments than in the LGE(+) segments (-11.8 vs -8.9%, 40.5 vs 29.7%/s, both P < 0.001). The max Ecc rate was higher in the FDG(-) segments than in the FDG(+) segments (39.2 vs 31.7%/s, P < 0.001), but the peak Ecc did not differ between the FDG(+) and FDG(-) segments (-11.2 vs -10.1%, P = 0.17). CONCLUSIONS: Strain analysis could reveal focal myocardial damage in the FDG(+) or the LGE(+) segments.

Morphologic Characterization of Pulmonary Nodules With Ultrashort TE MRI at 3T.

OBJECTIVE: Ultrashort TE (UTE) MRI has been shown to deliver high-resolution images comparable to CT images. Here we evaluate the potential of UTE-MRI for precise lung nodule characterization. SUBJECTS AND METHODS: Fifty-one patients (mean [± SD] age, 68.7 ± 10.8 years) with 119 nodules or masses (mean size, 17.4 ± 16.3 mm; range, 4-88 mm) prospectively underwent CT (1-mm slice thickness) and UTE-MRI (TE, 192 µs; 1 mm3 resolution). Two radiologists assessed nodule dimensions and morphologic features (i.e., attenuation, margins, and internal lucencies), in consensus for CT and in a blinded fashion for UTE-MRI. Sensitivity, specificity, and kappa statistics were calculated in reference to CT. RESULTS: Readers 1 and 2 underestimated the nodules' long axial diameter with UTEMRI by 1.2 ± 3.4 and 2.1 ± 4.2 mm, respectively (p < 0.001). The sensitivity and specificity of UTE-MRI for subsolid attenuation were 95.9% and 70.3%, respectively, for reader 1 and 97.1% and 71.4%, respectively, for reader 2 (κ = 0.71 and 0.68). With regard to margin characteristics, for lobulation, sensitivity was 70.6% and 54.9%, and specificity was 93.2% and 96.3% for readers 1 and 2, respectively; for spiculation, sensitivity was 61.5% and 48.0%, and specificity was 95.2% and 95.0%; and for pleural tags, sensitivity was 87.0% and 73.3%, and specificity was 93.8% and 95.0%. Finally, for internal lucencies, sensitivity was 72.7% and 61.3%, and specificity was 96.1% and 97.3% for readers 1 and 2, respectively (κ = 0.64-0.81 for reader 1 and 0.48-0.72 for reader 2). Interreader agreement for attenuation, margin characteristics, and lucencies was substantial to almost perfect with few exceptions (κ = 0.51-0.90). CONCLUSION: UTE-MRI systematically underestimated dimension measurements by approximately 1-2 mm but otherwise showed high diagnostic properties and interreader agreement, yet unprecedented by MRI, for nodule morphologic assessment.

Comparison of fat suppression capability for chest MR imaging with Dixon, SPAIR and STIR techniques at 3 Tesla MR system.

PURPOSE: To directly compare fat suppression efficacy of Dixon, spectral attenuated inversion recovery (SPAIR) and short tau inversion recovery (STIR) techniques for a 3T MR system. MATERIALS AND METHODS: Nineteen consecutive patients (11 men, 8 women; mean age 67.9years) underwent chest MR imaging. Contrast-noise ratio (CNR) between muscle and fat (CNRFat) was calculated by ROI measurement. Then, two radiologists used a five-point scale for visual assessment of image quality, fat suppression capability and lesion detection. Next, the quantitative calculations obtained with all three techniques were compared by means of Tukey's honest significant difference (HSD) test. Inter-observer agreements were assessed by kappa statistics and χ2 test. Fisher's least significant difference (LSD) test was used for comparison among all scores. RESULTS: CNRFat of SPAIR were significantly higher than those of Dixon and STIR (p<0.001). Inter-observer agreements were assessed as significantly moderate, substantial or almost perfect (0.51<κ<0.89, p<0.0001). Total image quality and fat suppression capability of Dixon and STIR were significantly higher than those of SPAIR (p<0.001). CONCLUSION: Dixon technique has better fat suppression capability on T2-weighted turbo SE imaging than SPAIR technique on chest MR imaging examined with a 3T MR system, although it can't substitute STIR technique on fat suppression and lesion visualization.

Value of three-dimensional T2-weighted turbo spin-echo imaging with tissue-specific variable refocusing flip angle for 3-T magnetic resonance imaging of prostate cancer: comparison with conventional two- and three-dimensional T2-weighted turbo spin-echo imaging.

PURPOSE: To investigate the impact of three-dimensional (3D) T2-weighted turbo spin-echo imaging (TSE-T2WI) with tissue-specific variable refocusing flip angle (TS-VRFA) on image quality and prostate cancer (PCa) detection and extraprostatic extension (EPE) evaluation compared to 2D TSE-T2WI and conventional 3D TSE-T2WI with volume isotropic TSE acquisition (VISTA). MATERIALS AND METHODS: Image data sets of 40 patients who underwent 3-T MRI before prostatectomy, including multiplane 2D T2WI, 3D T2WI with TS-VRFA and VISTA, and diffusion-weighted images were independently evaluated by two radiologists. The detectability of PCa and EPE of each sequence was assessed using areas by the receiver operating characteristic curve (AUC) analysis. Image quality measures and contrast ratios (CR) between cancerous lesions and non-cancerous regions for each T2WI were also evaluated. RESULTS: Overall image quality of TS-VRFA was better than that of VISTA and equivalent to 2D. The highest CR was obtained with TS-VRFA (P < 0.05). For both readers, no significances were observed in detectability for PCa detection between three sequences (P > 0.05). For both readers, there were no significant differences in AUC for EPE evaluation between three sequences (P > 0.05). CONCLUSION: 3D T2 WI using TS-VRFA could potentially replace multiplane 2D T2 WI for prostate cancer diagnosis with better image quality than VISTA.

Pancreatic fat content assessed by 1 H magnetic resonance spectroscopy is correlated with insulin resistance, but not with insulin secretion, in Japanese individuals with normal glucose tolerance.

AIMS/INTRODUCTION: Whereas some clinical studies have shown that excessive fat accumulation in the pancreas is associated with impairment of insulin secretion, others have not found such an association. 1 H magnetic resonance spectroscopy allows quantitative fat analysis in various tissues including the pancreas. The pathological relevance of pancreatic fat content (PFC) in Japanese individuals remains unclear, however. MATERIALS AND METHODS: We analyzed PFC in 30 Japanese individuals with normal glucose tolerance by 1 H magnetic resonance spectroscopy, and then investigated the relationships between PFC and indexes of insulin secretion and insulin sensitivity-resistance determined by an oral glucose tolerance test. We also measured hepatic fat content and intramyocellular lipid content by 1 H magnetic resonance spectroscopy, as well as visceral fat area and subcutaneous fat area by magnetic resonance imaging, and we examined the relationships between these fat content measures and oral glucose tolerance test-derived parameters. RESULTS: PFC was correlated with indexes of insulin sensitivity-resistance, but not with those of insulin secretion. Hepatic fat content and visceral fat area were correlated with similar sets of parameters as was PFC, whereas subcutaneous fat area was correlated with parameters of insulin secretion, and intramyocellular lipid content was not correlated with any of the measured parameters. The correlation between PFC and homeostasis model assessment of insulin resistance remained significant after adjustment for age, body mass index and sex. Among fat content measures, PFC was most highly correlated with hepatic fat content and visceral fat area. CONCLUSIONS: PFC was correlated with indexes of insulin resistance, but not with those of insulin secretion in non-obese Japanese individuals with normal glucose tolerance.

Comparison of FDG PET metabolic tumour volume versus ADC histogram: prognostic value of tumour treatment response and survival in patients with locally advanced uterine cervical cancer.

OBJECTIVE: To evaluate the prognostic utility of volume-based parameters of fluorine-18 fludeoxyglucose positron emission tomography (18F-FDG PET) and apparent diffusion coefficient (ADC) histogram analysis for tumour response to therapy and event-free survival (EFS) in patients with uterine cervical cancer receiving chemoradiotherapy. METHODS: The study included 21 patients diagnosed with locally advanced uterine cervical cancer who underwent pre-treatment MRI and 18F-FDG PET and were treated with concurrent chemoradiotherapy. 18F-FDG parameters: maximum and mean standardized uptake value; metabolic tumour volume (MTV); total lesion glycolysis (TLG); ADC parameters: maximum, mean and minimum values; percentile ADC values (10-90%); skewness and kurtosis of ADC were measured and compared between the responder and non-responder groups using a Wilcoxon rank-sum test. The Cox regression analysis and Kaplan-Meier survival curves were performed for EFS analysis. RESULTS: MTV and TLG of the primary tumour were significantly higher in the non-responder group than in the responder group (p = 0.04 and p = 0.01). Applying Cox regression multivariate analysis, MTV [hazard ratio (HR), 4.725; p = 0.036], TLG (HR, 4.725; p = 0.036) and 10-percentile ADC (HR, 5.207; p = 0.048) showed a statistically significant association with EFS. With the optimal cut-off value, the EFS rates above the cut-off value for MTV and TLG were significantly lower than that below the cut-off value (p = 0.002 and p = 0.002). CONCLUSION: Pre-treatment volume-based quantitative parameters of 18F-FDG PET may have better potential than ADC histogram for predicting treatment response and EFS in patients with locally advanced cervical cancer. Advances in knowledge: In this study, pre-treatment volume-based quantitative parameters of 18F-FDG PET had better potential than ADC histogram for predicting treatment response and survival in patients with locally advanced cervical cancer.

Diagnostic performance of different imaging modalities in the assessment of distant metastasis and local recurrence of tumor in patients with non-small cell lung cancer.

PURPOSE: To compare the diagnostic performance of positron emission tomography with [18F] fluoro-2-deoxy-glucose (FDG-PET) coregistered with magnetic resonance imaging (FDG-PET/MRI), MRI with and without diffusion-weighted imaging (DWI), FDG-PET fused with computed tomography (FDG-PET/CT) with brain contrast-enhanced (CE-) MRI, and routine radiological examination for assessment of postoperative recurrence in nonsmall-cell lung cancer (NSCLC) patients. MATERIALS AND METHODS: 96 consecutive postoperative NSCLC patients (52 men, 44 women; mean age 72 years) prospectively underwent whole-body 3T MRI with and without DWI; PET/CTs and routine radiological examinations consisted of CE-brain MRI, whole-body CE-CT, and bone scintigraphy. The patients were divided into a recurrence (n = 17) and a nonrecurrence (n = 79) group based on pathological and follow-up examinations. All coregistered PET/MRIs were generated by proprietary software. The probability of recurrence was visually assessed on a per-patient basis. Receiver operating characteristic analyses were used to compare the diagnostic performance of all methods. Finally, diagnostic capabilities were compared by means of McNemar's test. RESULTS: Areas under the curves (Azs) were significantly larger for PET/MRI and whole-body MRI with DWI (Az = 0.99) than for PET/CT (Az = 0.92, P < 0.05) and conventional radiological examination (Az = 0.91, P < 0.05). Specificity and accuracy of PET/MRI and MRI with and without DWI were significantly higher than those of PET/CT (P < 0.05) and routine radiological examination (P < 0.05). CONCLUSION: Whole-body FDG-PET/MRI and MRI with DWI were found to be more specific and accurate than FDG-PET/CT and routine radiological examinations for assessment of recurrence in NSCLC patients, although MRI with and without DWI demonstrated slightly lower sensitivity than PET/CT. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1707-1717.

Standard-, Reduced-, and No-Dose Thin-Section Radiologic Examinations: Comparison of Capability for Nodule Detection and Nodule Type Assessment in Patients Suspected of Having Pulmonary Nodules.

Purpose To compare the capability of pulmonary thin-section magnetic resonance (MR) imaging with ultrashort echo time (UTE) with that of standard- and reduced-dose thin-section computed tomography (CT) in nodule detection and evaluation of nodule type. Materials and Methods The institutional review board approved this study, and written informed consent was obtained from each patient. Standard- and reduced-dose chest CT (60 and 250 mA) and MR imaging with UTE were used to examine 52 patients; 29 were men (mean age, 66.4 years ± 7.3 [standard deviation]; age range, 48-79 years) and 23 were women (mean age, 64.8 years ± 10.1; age range, 42-83 years). Probability of nodule presence was assessed for all methods with a five-point visual scoring system. All nodules were then classified as missed, ground-glass, part-solid, or solid nodules. To compare nodule detection capability of the three methods, consensus for performances was rated by using jackknife free-response receiver operating characteristic analysis, and κ analysis was used to compare intermethod agreement for nodule type classification. Results There was no significant difference (F = 0.70, P = .59) in figure of merit between methods (standard-dose CT, 0.86; reduced-dose CT, 0.84; MR imaging with UTE, 0.86). There was no significant difference in sensitivity between methods (standard-dose CT vs reduced-dose CT, P = .50; standard-dose CT vs MR imaging with UTE, P = .50; reduced-dose CT vs MR imaging with UTE, P >.99). Intermethod agreement was excellent (standard-dose CT vs reduced-dose CT, κ = 0.98, P < .001; standard-dose CT vs MR imaging with UTE, κ = 0.98, P < .001; reduced-dose CT vs MR imaging with UTE, κ = 0.99, P < .001). Conclusion Pulmonary thin-section MR imaging with UTE was useful in nodule detection and evaluation of nodule type, and it is considered at least as efficacious as standard- or reduced-dose thin-section CT. © RSNA, 2017 Online supplemental material is available for this article.

Increased Pittsburgh Compound-B Accumulation in the Subcortical White Matter of Alzheimer's Disease Brain.

Using 11C-Pittsburgh compound B (PiB)-PET and MRI volume data, we investigated whether white matter (WM) PiB uptake in Alzheimer's disease (AD) brain is larger than that of cortical PiB uptake-negative (PiB-negative) brain. Forty-five subjects who underwent both PiB-PET and MRI were included in the study (32 AD patients with cortical PiB-positive and 13 cortical amyloid -negative patients). Individual areas of gray matter (GM) and WM were segmented, then regional GM and WM standard uptake value ratio (SUVR) normalized to cerebellar GM with partial volume effects correction was calculated. Three regional SUVRs except WM in the centrum semiovale in the AD group were significantly larger than those in the PiB-negative groups. Frontal WM SUVR in the AD group vs frontal WM SUVR in the PiB-negative group was 2.57 ± 0.55 vs 1.64 ± 0.22; parietal, 2.50 ± 0.52 vs 1.74 ± 0.22; posterior cingulate, 2.84 ± 0.59 vs 1.73 ± 0.22; and WM in the centrum semiovale, 2.21 ± 0.53 vs 2.42 ± 0.36, respectively. We found that PiB uptake in AD brain is significantly larger than that in PiB-negative brain in the frontal, parietal and posterior cingulate subcortical WM, except in the centrum semiovale.

Perioperative Changes in Cerebral Perfusion Territories Assessed by Arterial Spin Labeling Magnetic Resonance Imaging Are Associated with Postoperative Increases in Cerebral Blood Flow in Patients with Carotid Stenosis.

OBJECTIVE: The magnetic resonance imaging technique known as territorial arterial spin labeling (TASL) allows for noninvasive visualization of perfusion territories. The objective of this study was to use TASL to assess the relationship between perioperative changes in the perfusion territories of the internal carotid artery (ICA) and cerebral blood flow (CBF) after carotid revascularization. METHODS: In 32 patients, ICA perfusion volume (PV) and CBF were measured before and after carotid endarterectomy/carotid artery stenting using TASL and single-photon emission computed tomography, respectively. ICA flow was measured during carotid endarterectomy before and after reconstruction, using an electromagnetic flowmeter. Eleven healthy volunteers, as the normal control group, underwent TASL evaluation. RESULTS: We classified patients into 2 groups: the normal PV group (ICA PV ≥ mean-2 standard deviation of healthy volunteers; n = 13) and the reduced PV group (ICA PV < mean-2 standard deviation; n = 19). The postoperative increase in the ICA PV and CBF were significantly greater in the reduced PV group than in the normal group (90.4% ± 131.8% vs. 10.5 ± 9.8%, P = 0.017, 32.0 ± 25.7% vs. 10.5% ± 10.7%, P = 0.0032, respectively). ICA flow increased significantly after reconstruction in both the normal PV group (115.1 ± 48.1 mL/minute to 159.1 ± 53 mL/minute; P = 0.016) and reduced PV group (57.8 ± 38.3 mL/minute to 182.3 ± 52.6 mL/minute; P < 0.0001). However, in some patients in the reduced PV group, the PV increased only slightly, whereas the ICA flow markedly increased, which resulted in a large CBF increase, such as hyperperfusion. CONCLUSIONS: The TASL study suggested that an imbalance between increases in the PV and ICA flow could play an important role in the pathophysiology underlying postoperative abnormal increases in CBF.

Radiologic-Pathologic Correlation of Primary and Secondary Cardiomyopathies: MR Imaging and Histopathologic Findings in Hearts from Autopsy and Transplantation.

Cardiac magnetic resonance (MR) imaging with late gadolinium enhancement (LGE) is used to detect and assess the myocardial damage seen with a variety of cardiomyopathies. Gadolinium-based contrast material accumulates in the expanded interstitial space of the myocardium. Areas with LGE correspond to replacement fibrosis, fibrofatty change, epithelioid granuloma, inflammatory cell infiltration, cardiomyocyte necrosis, and amyloid deposition-conditions that represent a focal increase in interstitial space. Areas without LGE correspond to interstitial or plexiform fibrosis, mildly degenerated cardiomyocytes, inflammatory cell infiltration, and diffuse amyloid deposition-conditions that represent diffuse increases in interstitial space. LGE MR imaging cannot depict these diffuse changes and does not enable quantitative evaluation of this increased interstitial space because on inversion-recovery MR images, the inversion time is adjusted to null the signal from normal-appearing or the least enhancing regions of the myocardium. Thus, the absence of LGE does not always indicate normal myocardial tissue. The use of current T1 mapping techniques enables one to overcome these drawbacks of LGE imaging, detect diffuse myocardial abnormalities, and perform quantitative analysis of the interstitial space. The authors describe the histopathologic and corresponding cardiac MR imaging findings of hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, cardiac sarcoidosis, giant cell myocarditis, and cardiac amyloidosis-mainly those seen on LGE MR images-as assessed by using whole-heart specimens obtained from autopsy or transplantation. ©RSNA, 2017.

Relationship between the uptake of 18F-borono-L-phenylalanine and L-[methyl-11C] methionine in head and neck tumors and normal organs.

BACKGROUND AND PURPOSE: The purpose of this study was to determine the distribution of 4-borono-2-18F-fluoro-phenylalanine (18F-BPA) and L-[methyl-11C] methionine (11C-Met) in normal organs and tumors and to evaluate the usefulness of 11C-Met/PET in screening potential candidates for boron neutron capture therapy (BNCT). MATERIAL METHODS: Seven patients who had at least one histologically confirmed head and neck tumor were included in this study. They underwent both whole-body 18F-BPA-PET/CT and 11C-Met-PET/CT within a span of 6 months. Uptake was evaluated using the maximum standardized uptake value (SUVmax). Regions of interest (ROIs) were placed within the tumors and target organs of brain, thyroid, submandibular gland, lung, liver, esophagus, stomach pancreas, spleen, muscle, and bone marrow. RESULTS: The tumor SUVmax of FBPA and 11C-Met showed strong correlation (r 2 = 0.72, P = 0.015). Although 18F-BPA and 11C-Met showed markedly different uptake in some organs (submandibular gland, liver, heart, stomach pancreas, spleen, and bone marrow), the uptake of 11C-Met was consistently higher than that of 18F-BPA in these cases. CONCLUSION: 11C-Met PET/CT might be used instead of 18F-BPA PET/CT to predict the accumulation of 10B in tumors and to select candidates for BNCT. However, it would not be suitable for evaluating accumulation in some normal organs. Therefore, the 18F-BPA-PET study remains a prerequisite for BNCT. This is the first report of the correlation between 18F-BPA and 11C-Met accumulation.

Xenon-enhanced CT using subtraction CT: Basic and preliminary clinical studies for comparison of its efficacy with that of dual-energy CT and ventilation SPECT/CT to assess regional ventilation and pulmonary functional loss in smokers.

PURPOSE: To prospectively and directly compare the capability for assessments of regional ventilation and pulmonary functional loss in smokers of xenon-ventilation CT obtained with the dual-energy CT (DE-CT) and subtraction CT (Sub-CT) MATERIALS AND METHODS: Twenty-three consecutive smokers (15 men and 8 women, mean age: 69.7±8.7years) underwent prospective unenhanced and xenon-enhanced CTs, the latter by Sub-CT and DE-CT methods, ventilation SPECT and pulmonary function tests. Sub-CT was generated from unenhanced and xenon-enhanced CT, and all co-registered SPECT/CT data were produced from SPECT and unenhanced CT data. For each method, regional ventilation was assessed by using a 11-point scoring system on a per-lobe basis. To determine the functional lung volume by each method, it was also calculated for individual sublets with a previously reported method. To determine inter-observer agreement for each method, ventilation defect assessment was evaluated by using the χ2 test with weighted kappa statistics. For evaluation of the efficacy of each method for pulmonary functional loss assessment, functional lung volume was correlated with%FEV1. RESULTS: Each inter-observer agreement was rated as substantial (Sub-CT: κ=0.69, p<0.0001; DE-CT: κ=0.64, p<0.0001; SPECT/CT: κ=0.64, p<0.0001). Functional lung volume for each method showed significant to good correlation with%FEV1 (Sub-CT: r=0.72, p=0.0001; DE-CT: r=0.74, p<0.0001; SPECT/CT: r=0.66, p=0.0006). CONCLUSION: Xenon-enhanced CT obtained by Sub-CT can be considered at least as efficacious as that obtained by DE-CT and SPECT/CT for assessment of ventilation abnormality and pulmonary functional loss in smokers.

Tailored Duration of Contrast Material Injection in High-Pitch Computed Tomographic Aortography With a Double-Level Test Bolus Method.

OBJECTIVES: To achieve the efficient usage of contrast material (CM) in high-pitch CT aortography, an appropriate duration of the CM injection is crucial. We used a modification of the double-level test bolus method for determination of proper injection duration with the aim of evaluating the image quality of tailored-duration CM injection compared with that of a fixed duration. MATERIALS AND METHODS: The institutional review board approved retrospective review of 80 consecutive subjects who had undergone high-pitch 70-kVp CT aortography with a modified double-level test bolus method. The interval between peak enhancement at the aortic root and femoral artery was derived from the time/attenuation curves. A total of 40 subjects underwent CT aortography with individually set duration time from the results. The remaining subjects underwent CT aortography with a fixed-duration time. The density values at several parts of the aorta were assessed. The differences in image quality and CM amount used for each method were assessed by Welch test. RESULTS: The injection duration was almost 50% shorter (median, 15 seconds; range, 11-25 seconds) when individually tailored. The mean CM amount was reduced by 50% (46.2-23.9 mL, P < 0.01). The range of mean CT attenuation throughout the aorta was not significantly different between the 2 methods (316-327 HU and 305-321 HU, P > 0.05, respectively). CONCLUSIONS: The modified double-level test bolus method in high-pitch CT aortography can significantly reduce the amount of CM without adversely affecting image quality.

Improved image quality in abdominal CT in patients who underwent treatment for hepatocellular carcinoma with small metal implants using a raw data-based metal artifact reduction algorithm.

OBJECTIVES: To determine the value of a raw data-based metal artifact reduction (SEMAR) algorithm for image quality improvement in abdominal CT for patients with small metal implants. METHODS: Fifty-eight patients with small metal implants (3-15 mm in size) who underwent treatment for hepatocellular carcinoma were imaged with CT. CT data were reconstructed by filtered back projection with and without SEMAR algorithm in axial and coronal planes. To evaluate metal artefact reduction, mean CT number (HU and SD) and artefact index (AI) values within the liver were calculated. Two readers independently evaluated image quality of the liver and pancreas and visualization of vasculature using a 5-point visual score. HU and AI values and image quality on images with and without SEMAR were compared using the paired Student's t-test and Wilcoxon signed rank test. Interobserver agreement was evaluated using linear-weighted κ test. RESULTS: Mean HU and AI on images with SEMAR was significantly lower than those without SEMAR (P < 0.0001). Liver and pancreas image qualities and visualizations of vasculature were significantly improved on CT with SEMAR (P < 0.0001) with substantial or almost perfect agreement (0.62 ≤ κ ≤ 0.83). CONCLUSIONS: SEMAR can improve image quality in abdominal CT in patients with small metal implants by reducing metallic artefacts. KEY POINTS: • SEMAR algorithm significantly reduces metallic artefacts from small implants in abdominal CT. • SEMAR can improve image quality of the liver in dynamic CECT. • Confidence visualization of hepatic vascular anatomies can also be improved by SEMAR.

Standard-dose vs. low-dose CT protocols in the evaluation of localized lung lesions: Capability for lesion characterization-iLEAD study.

OBJECTIVE: To determine the lesion characterization capability by low dose CT for localized lung lesions in comparison with standard dose CT. SUBJECTS AND METHODS: Approval for this study was granted by our Institutional Review Board. Fifty-two consecutive patients (36 males and 16 females, median age of 71 years.) who had CT examinations for evaluation of lung lesions comprise the study population. Two chest CT scans were performed with current time product of 50 and 150 mAs at 120 kVp, with the same scan length with a 16 detector-row CT scanner. Three readers evaluated 52 target lesions and assigned an overall impression score to each target lesion, using a 5 point scale from 1 (definitely benign) to 5 (definitely malignant). Six features of the lesions including lesion type, margin characteristics, calcification, lobulation, speculation, and pleural indentation were also reported with 5-point scales. The weighted kappa analyses and receiver operating characteristic analysis were used for analysis. RESULTS: The mean kappa value between low-and standard-dose CT was 0.82 for overall impression of the lesions, showing almost perfect agreement. Area under the curve of low-dose CT (Az = 0.74) had no significant difference from that of standard-dose CT (Az = 0.74) (p = 0.61). The kappa values for six lesion features ranged from 0.45 to 0.83, showing moderate to almost perfect agreement. CONCLUSION: Lesion characterization capability by low-dose CT images was comparable to that by standard-dose CT images and therefore sufficient for evaluation of localized lung lesions.