Triexponential function analysis of diffusion-weighted MRI for diagnosing prostate cancer.

BACKGROUND: To evaluate more detailed information noninvasively through on diffusion and perfusion in prostate cancer (PCa) using triexponential analysis of diffusion-weighted imaging (DWI). METHODS: Sixty-three prostate cancer patients underwent preoperative 3.0 Tesla MRI including eight b-values DWI. Triexponential analysis was performed to obtain three diffusion coefficients (Dp , Df , Ds ), as well as fractions (Fp , Ff , Fs ). Each diffusion parameter for cancerous lesions and normal tissues was compared and the relationship between diffusion parameters and Gleason score (GS) was assessed. K(trans) , Ve , and the ratios of intracellular components measured in histopathological specimens were compared with diffusion parameters. RESULTS: Dp was significantly greater for cancerous lesions than normal peripheral zone (PZ) (P < 0.001), whereas Dp in transition zone (TZ) showed no significant difference (P = 0.74, 95% confidence interval (CI) = -4.69-6.48). Ds was significantly smaller for each cancerous lesions in PZ and TZ (P < 0.001, respectively). There was no significant difference in Df between cancerous lesions and normal tissues in PZ and TZ (P = 0.07, 95% CI = -0.29-0.12 and P = 0.53, 95% CI = -3.51-2.29, respectively). D obtained with biexponential analysis were significantly smaller in cancerous lesions than in normal tissue in PZ and TZ (P < 0.001 for both), while D* in PZ and TZ showed no significant difference (P = 0.14, 95% CI = -1.60-0.24 and P = 0.31, 95% CI = -3.43-1.16, respectively). Dp in PZ and TZ showed significant correlation with K(trans) (R = 0.85, P < 0.001; R = 0.81, P < 0.001, respectively), while D(*) in PZ obtained with biexponential analysis showed no such correlation (P = 0.08, 95% CI = -0.14-0.30). Fs was significantly correlated with intracellular space fraction evaluated in histopathological specimens in PZ and TZ cancer (R = 0.41, P < 0.05; R = 0.59, P < 0.001, respectively). Ff and Fs correlated significantly with GS in PZ and TZ cancer (PZ: R = -0.44, P < 0.05; R = 0.37, P < 0.05, TZ: R = -0.59, P < 0.05; R = 0.57, P < 0.05, respectively). CONCLUSION: Triexponential analysis is a noninvasive approach that can provide more detailed information regarding diffusion and perfusion of PCa than biexponential analysis.

Contrast-enhanced multidetector-row computed tomography vs. Time-resolved magnetic resonance angiography vs. contrast-enhanced perfusion MRI: assessment of treatment response by patients with inoperable chronic thromboembolic pulmonary hypertension.

PURPOSE: To compare therapeutic effect assessment capability of multidetector-row computed tomography (MDCT), magnetic resonance angiography (MRA), and dynamic perfusion MRI for chronic thromboembolic pulmonary hypertension (CTEPH) patients. MATERIALS AND METHODS: Twenty-four consecutive CTEPH patients treated with conventional therapy underwent pre- and posttherapeutic MDCT, MRA, dynamic perfusion MRI, 6-minute walk distance (6-MWD), cardiac ultrasound (US), and right heart catheterization. According to therapeutic results, all patients were divided into response (n = 13) and nonresponse (n = 11) groups. CTEPH indexes for MDCT (CTEPH(CT) ) and MRA (CTEPH(MRA) ) were calculated on the basis of embolic burden. Pulmonary perfusion parameter maps were generated from all perfusion MR data, followed by determination of improvements in mean perfusion parameter at regions of interest (ROIs) for each patient. Receiver operating characteristic (ROC)-based positive tests were performed to determine the feasible threshold values for distinguishing two groups. Finally, diagnostic capabilities were compared by means of McNemar's test. RESULTS: When feasible threshold values adapted, specificity (90.9 〈10/11〉%, P < 0.05) and accuracy (95.8 〈23/24〉%, P < 0.05) for improvement in pulmonary blood flow were significantly higher than those for CTEPH(CTA) (specificity: 36.4 〈4/11〉%, accuracy: 70.8 〈17/24〉%). CONCLUSION: Dynamic perfusion MRI has better capability for assessment of therapeutic effect on CTEPH patients than does MDCT.

Diffusion-weighted MRI versus 18F-FDG PET/CT: performance as predictors of tumor treatment response and patient survival in patients with non-small cell lung cancer receiving chemoradiotherapy.

OBJECTIVE: The purpose of this study was to compare the predictive capabilities of diffusion-weighted MRI (DWI) and 18F-FDG PET/CT for tumor response to therapy and survival in patients with non-small cell lung cancer (NSCLC) receiving chemoradiotherapy. SUBJECTS AND METHODS: The study included 64 patients with NSCLC diagnosed as stage III who underwent pretherapeutic DWI and FDG PET/CT and were treated with chemoradiotherapy. For quantitative prediction, apparent diffusion coefficient (ADC) for DWI and maximum standardized uptake value (SUVmax) for PET/CT were measured at all targeted lesions and averaged to obtain final values for each patient. To evaluate the predictive capability of either index for distinguishing partial response and nonresponse (stable or progressive disease) groups, receiver operating characteristic analysis was performed, and sensitivity, specificity, and accuracy of the two modalities were compared using the McNemar test. Finally, overall and progression-free survival curves divided by the corresponding threshold value were compared by means of the log-rank test. RESULTS: The area under the curve (Az) for ADC (Az=0.84) was significantly larger than that for SUVmax (Az=0.64, p<0.05). The application of feasible threshold values resulted in specificity (44.4%) and accuracy (76.6%) of DWI becoming significantly higher than those of PET/CT (specificity, 11.1%; p<0.05 and accuracy, 67.2%, p<0.05). In addition, only overall survival and progression-free survival of the two groups divided by ADC at 2.1×10(-3) mm2/s and SUVmax at 10 showed a significant difference (p<0.05). CONCLUSION: DWI may have better potential than FDG PET/CT for prediction of tumor response to therapy in NSCLC patients before chemoradiotherapy.

N stage disease in patients with non-small cell lung cancer: efficacy of quantitative and qualitative assessment with STIR turbo spin-echo imaging, diffusion-weighted MR imaging, and fluorodeoxyglucose PET/CT.

PURPOSE: To prospectively compare the diagnostic capability of short inversion time inversion-recovery (STIR) turbo spin-echo (SE) imaging, diffusion-weighted (DW) magnetic resonance (MR) imaging, and fluorodeoxyglucose (FDG) combined positron emission tomography (PET) and computed tomography (CT) in N stage assessment in patients with non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: This prospective study was approved by the institutional review board, and written informed consent was obtained from all patients. A total of 250 consecutive patients with NSCLC (136 men; mean age, 73 years; 114 women; mean age, 72 years) prospectively underwent pretherapeutic STIR turbo SE imaging, DW MR imaging, and FDG PET/CT, as well as surgical and pathologic examinations (N0 disease, n = 157; N1 disease, n = 72; N2 disease, n = 16; N3 disease, n = 5). Lymph node-to-saline ratio (LSR), lymph node-to-muscle ratio (LMR), apparent diffusion coefficient (ADC), maximal standardized uptake value (SUV(max)), and visual scoring were assessed for 135 metastatic lymph nodes and 135 randomly selected nonmetastatic lymph nodes. Receiver operating characteristic curve analysis was used to determine feasible threshold values. Diagnostic capabilities for N stage assessment were compared with the McNemar test on a per-patient basis. RESULTS: When feasible, threshold values were used for quantitative assessment; sensitivity and accuracy of LSR and LMR (sensitivity, 82.8%; accuracy, 86.8%) proved to be significantly higher than those of ADC (sensitivity: 74.2%, P = .01; accuracy: 84.4%, P = .04) and SUV(max) (sensitivity: 74.2%, P = .01). For qualitative assessment, sensitivity of STIR turbo SE imaging (77.4%) was significantly higher than that of DW MR imaging (71.0%, P = .03) and FDG PET/CT (69.9%, P = .02). CONCLUSION: Quantitative and qualitative assessments of N stage disease in patients with NSCLC obtained with STIR turbo SE MR imaging are more sensitive and/or more accurate than those obtained with DW MR imaging and FDG PET/CT. SUPPLEMENTAL MATERIAL: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11110281/-/DC1.

Comparison of STIR turbo SE imaging and diffusion-weighted imaging of the lung: capability for detection and subtype classification of pulmonary adenocarcinomas.

OBJECTIVE: The aim of the study was to evaluate the diagnostic performance of diffusion-weighted imaging (DWI) for detection and subtype classification in pulmonary adenocarcinomas through comparison with short TI inversion recovery turbo spin-echo imaging sequence (STIR). METHODS: Thirty-two patients (mean age, 65.2 years) with 33 adenocarcinomas (mean diameter, 27.6 mm) were enrolled in this study. The detection rates of both sequences were compared. The ADC values on DWI and the contrast ratio (CR) between cancer and muscle on STIR were measured and those were compared across subtype classifications. Finally, ROC-based positive tests were performed to differentiate subtype classifications, and differentiation capabilities were compared. RESULTS: The DWI detection rate [85% (28/33)] was significantly lower than that of STIR [100% (33/33), P < 0.05]. The ADC values showed no significant difference regarding subtype classification; however, the CRs of bronchio-alveolar carcinomas (BACs) were significantly lower than those of other types (P < 0.05). When threshold values for differentiating BACs from others were adapted, the sensitivity and accuracy of DWI were significantly lower than those of STIR (P < 0.05). For differentiating adenocarcinomas with mixed subtypes from those with no BA component, there were no significant differences between the two sequences. CONCLUSION: STIR is more sensitive for detection and subtype classification than DWI.

Abdominal apparent diffusion coefficient measurements: effect of diffusion-weighted image quality and usefulness of anisotropic images.

This study aimed to assess the effect of diffusion-weighted image (DWI) quality on abdominal apparent diffusion coefficient (ADC) measurements and the usefulness of anisotropic images. Twenty-six patients (10 men and 16 women; mean, 58.1 years) who underwent DW imaging and were diagnosed not to have any abdominal diseases were analyzed. Single-shot spin-echo echo-planar DW imaging was performed, and one isotropic and three orthogonal anisotropic images were created. ADCs were calculated for liver (four segments), spleen, pancreas (head, body, tail) and renal parenchyma. Image quality for each organ part was scored visually. We estimated the correlation between ADC and image quality and evaluated the feasibility of using anisotropic images. ADCs and image quality were affected by motion probing gradient directions in the liver and pancreas. A significant inverse correlation was found between ADC and image quality. The r values for isotropic images were -.46, -.48, -.70 and -.28 for the liver, spleen, pancreas and renal parenchyma, respectively. Anisotropic images had the best quality and lowest ADC in at least one organ part in 17 patients. DWIs with the best quality among isotropic and anisotropic images should be used in the liver and pancreas.

AUTOMATIC ACQUISITION OF CT RADIATION DOSE DATA: USING THE DIAGNOSTIC REFERENCE LEVEL FOR RADIATION DOSE OPTIMIZATION.

The present work describes that we try to construct a system that collects dose information that performed CT examination from multiple facilities and unified management. The results of analysis are compared with other National diagnostic reference level (DRL), and the results are fed back to each facility and the cause of the abnormal value is investigated for dose optimization. Medical information collected 139 144 tests from 33 CT devices in 13 facilities. Although the DRL of this study is lower than that of Japan DRL, it was higher than the DRL of each country. When collecting all the examination, it is thought that the variation of the dose due to the error other than the intended imaging site is large. In future, we should continue to collect information in order to DRL renewal and we also think that it is desirable to collect information on physique and detailed scan region as well.

Cardiovascular magnetic resonance T2 mapping can detect myocardial edema in idiopathic dilated cardiomyopathy.

Myocardial edema and inflammation play an important role in dilated cardiomyopathy (DCM). This pathologic condition can be identified noninvasively using cardiovascular magnetic resonance imaging (CMR). The purpose of this study was to determine the effectiveness of T2 values obtained with T2 mapping in the detection of edema in DCM patients, compared with that of conventional T2-weighted imaging (T2WI). CMR was used for 15 normal controls (NML) and 26 DCM patients. The DCM patients were classified as having either mild dysfunction with a left ventricular ejection fraction (EF) >35% or severe dysfunction with an EF ≤35%. Myocardial edema was assessed by both T2 mapping and T2WI. The differences between the T2 values determined from T2 mapping and the T2 ratios that were calculated from the T2WI were compared among the NML, mild DCM, and severe DCM patients. The T2 values for the NML, mild DCM, and severe DCM patients were 51.2 ± 1.6, 61.2 ± 0.37, and 67.4 ± 6.8, respectively (P < 0.05 for each pair), and the corresponding T2 ratios were 1.88 ± 0.09, 2.12 ± 0.37, and 2.04 ± 0.34, respectively (P > 0.05). T2 mapping clearly showed that the myocardial water content was larger in DCM patients than in NML controls and that the myocardial water content increased as the disease progressed. Thus, T2 mapping is a useful technique for the diagnosis and quantitation of diffuse myocardial edema.

Magnetic resonance imaging (MRI) of articular cartilage of the knee using ultrashort echo time (uTE) sequences with spiral acquisition.

The objective of this study was to evaluate the sensitivity of ultrashort echo time (uTE) sequence for visualisation of calcified deep layers of articular cartilage. MRI with a uTE sequence was performed on five healthy volunteers. Signals from the calcified deep layers of the articular knee cartilage were evaluated on uTE subtraction images and computed tomography images. The calcified deep layers of the articular cartilage changed from having a low to a high signal when imaged with a uTE sequence. The reported uTE sequence was effective in imaging the deep layers of the knee cartilage.

Neuroimaging features of xeroderma pigmentosum group A.

Xeroderma pigmentosum group A (XPA) is a hereditary dermatological disease in which hypersensitivity to ultraviolet radiation and various neurological symptoms are observed. In this study, to evaluate the degeneration occurring in the brain of XPA patients, neurological examinations by an established neurologist and 3-Tesla magnetic resonance imaging (MRI) were performed in 10 Japanese XPA patients. MRI studies included diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS) in addition to conventional sequences. Neurological examinations revealed various deteriorations in the both central and peripheral nervous systems in all subjects. MRI studies demonstrated age-dependent decline in multimodalities. Severe brain atrophy in conventional sequences, decreased fractional anisotropy (FA) value in DTI, and reduced NAA/Cre ratio in MRS were observed in the adult patients. Multimodal MRI studies unmask the neurological deterioration in XPA patients.

Comparison of capability of dynamic O2-enhanced MRI and quantitative thin-section MDCT to assess COPD in smokers.

PURPOSE: The purpose of this study was to directly and prospectively compare the capability of dynamic O(2)-enhanced MRI and quantitatively assessed thin-section MDCT to assess smokers' COPD in a large prospective cohort. MATERIALS AND METHODS: The GOLD criteria for smokers were used to classify 187 smokers into four clinical stage groups as follows: smokers without COPD (n=56) and with mild (n=54), moderate (n=52) and severe or very severe COPD (n=24). All smokers underwent dynamic O(2)-enhanced MRI, MDCT and pulmonary function tests. Mean relative enhancement ratio and mean wash-in time on MRI and CT-based functional lung volume (CT-based FLV) as well as the ratio of airway wall area to total airway area on MDCT were computationally calculated. Then, all indexes were significantly correlated with functional parameters. To determine the efficacy of all indexes for clinical stage classification, the indexes for the four clinical groups were statistically compared by using Tukey's honestly significant difference multiple comparison test. RESULTS: All indexes had significant correlations with functional parameters (p<0.0001). All indexes except CT-based FLV in all groups had significant differences each other (p<0.05). CONCLUSIONS: Dynamic O(2)-enhanced MRI for assessment of COPD in smokers is potentially as efficacious as quantitatively assessed thin-section MDCT.

A preliminary study of the T1rho values of normal knee cartilage using 3T-MRI.

INTRODUCTION: To investigate the degree of the effect of aging and weight-bearing on T1rho values in normal cartilage. MATERIALS AND METHODS: Thirty-two asymptomatic patients were examined using 3.0-T magnetic resonance imaging (MRI) to determine knee cartilage T1rho values and T2 values. The femoral and tibial cartilage was divided into weight-bearing (WB-Rs) and less-weight-bearing (LWB-Rs) regions. Single regression analysis was used to assess the relationship between cartilage T1rho values and age and between T2 values and age. Analysis of variance and post hoc-testing were used to evaluate differences in WB-Rs and LWB-Rs cartilage T1rho values and T2 values. Multiple linear regression modeling was performed to predict cartilage T1rho values. RESULTS: Cartilage T1rho values correlated positively with age for all cartilage regions tested (p<0.001). There were no significant correlations between cartilage T2 values and age. In both the medial femoral and tibial cartilage, T1rho values were significantly higher in WB-Rs than in LWB-Rs (p<0.05). There were no significant differences in T2 values between WB-Rs and LWB-Rs. Multiple linear regression analysis showed that both age and weight-bearing were significant predictors of increased medial knee cartilage T1rho values (p<0.001). CONCLUSIONS: Aging and the degree of weight-bearing correlate with the change in cartilage T1rho values. Based on multiple regression modeling, aging may be a more important factor than weight-bearing for cartilage T1rho values.

The natural degeneration course in the T1rho values of normal knee cartilage.

The purpose of our study is to investigate whether there is an age-related change in T1 rho values and to evaluate the effects of weight bearing on age-related increase in T1 rho values of normal cartilage. Thirty-two asymptomatic patients were examined using a 3.0T MRI to determine knee cartilage T1 rho values. Femorotibial and patella cartilage was defined as weight-bearing cartilage (WB-C) and non-weight-bearing cartilage (NWB-C), respectively. The femoral cartilage was divided into weight-bearing (WB-P) and less-weight-bearing (LWB-P) portions. Pearson's correlation coefficient and single regression analysis were used to assess the relationship between cartilage T1 rho values and age. The slopes of the regression lines of cartilage T1 rho values and age were compared between WB-C and NWB-C and between WB-P and LWB-P. Cartilage T1 rho values correlated positively with aging for all cartilage regions and all age groups (p<0.001). In the medial femoral cartilage, the age-related increase in T1 rho values was significantly greater for WB-P than for NWB-P (p<0.05). For several cartilage regions, this increase was greater for WB-C than for LWB-C (p<0.05). The T1 rho value is very sensitive to age-related cartilage degeneration and weight bearing-related degeneration, and hence may be a very sensitive and useful measure for the early diagnosis of osteoarthritis.

Detection of bone metastases in non-small cell lung cancer patients: comparison of whole-body diffusion-weighted imaging (DWI), whole-body MR imaging without and with DWI, whole-body FDG-PET/CT, and bone scintigraphy.

PURPOSE: To prospectively compare the capability for bone metastasis assessment of whole-body diffusion-weighted imaging (DWI), magnetic resonance imaging (MRI) without and with DWI, [(18)F] fluoro-2-D-glucose positron emission tomography with computed tomography (FDG-PET/CT) and bone scintigraphy in non-small cell carcinoma (NSCLC) patients. MATERIALS AND METHODS: In all, 115 consecutive NSCLC patients (66 men, 49 women; mean age 72 years) prospectively underwent whole-body MRI, PET/CT, and bone scintigraphy before treatment. For each method, probability of metastasis was independently assessed by using a 5-point visual scoring system on a per-site basis. Receiver operating characteristic (ROC)-based positive tests were used to determine the practical threshold value for each method on a per-site basis. Sensitivities, specificities, and accuracies were then compared on a per-site and per-patient basis by means of McNemar's test. RESULTS: When the practical threshold values were adapted, specificity and accuracy of whole-body MRI with DWI were significantly higher than those of bone scintigraphy and PET/CT (P < 0.05). On a per-patient basis, specificity and accuracy of whole-body MRI with DWI were significantly higher than those of bone scintigraphy (P < 0.05). CONCLUSION: Whole-body MRI with DWI can be used for bone metastasis assessment of NSCLC patients as accurate as bone scintigraphy and/or PET/CT.