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Purpose: Minimal misregistration of fused PET and MRI images can be achieved with simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI). However, the acquisition of multiple MRI sequences during a single PET emission scan may impair fusion precision of each sequence. This study evaluated the diagnostic utility of time-synchronized PET/MRI using an MR active trigger and a Bayesian penalized likelihood reconstruction algorithm (BPL) to assess the locoregional extension of endometrial cancer., Methods: Fifty-five patients with endometrial cancer who underwent pelvic 2-deoxy-2-[ 18 F]fluoro-D-glucose PET/MRI were retrospectively evaluated. The PET emission time for the BPL reconstruction was determined by the MR active trigger of each MR sequence. The concordance rates of image interpretation with pathological T-staging, diagnostic performance for deep myometrial invasion (MI), and diagnostic confidence levels were evaluated by two readers and compared between time-synchronized, overlapping (conventional and simultaneous, but not time-synchronized), and sequential (not simultaneous) PET/MRI and MRI with diffusion-weighted imaging. Misregistration of the PET/MRI-fused images was determined by evaluating the differences in bladder dimensions., Results: The T classification by time-synchronized PET/MRI was the most concordant with the pathological T classification for the two readers. Time-synchronized PET/MRI had a significantly higher diagnostic performance for deep MI and higher confidence level scores than overlapping PET/MRI for the novice reader (p = 0.033 and p = 0.038, respectively). The differences in bladder dimension on sequential PET/MRI were significantly larger than those on overlapping and time-synchronized PET/MRI (p <0.001)., Conclusion: Time-synchronized PET/MRI is superior to conventional PET/MRI for assessing the locoregional extension of endometrial cancer., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Munenobu Nogami reports off-line reconstruction tool (Duetto) was provided by GE HealthCare. Takako Kurimoto is an employee of GE HealthCare. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper]., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

The glymphatic system is considered to play a pivotal role in the clearance of disease-causing proteins in neurodegenerative diseases. This study employed MR diffusion tensor imaging (DTI) to evaluate glymphatic system function and its correlation with brain amyloid accumulation levels measured using [ 11 C]Pittsburgh compound-B (PiB) PET/MRI. Fifty-six patients with mild cognitive impairment and early Alzheimer's disease (AD: 70 ± 11 y) underwent [ 11 C]PiB PET/MRI to assess amyloid deposition and were compared with 27 age-matched cognitively normal volunteers (CN: 69 ± 10y). All participants were evaluated for cognitive function using the Mini Mental State Examination (MMSE) before [ 11 C]PiB PET/MRI. DTI images were acquired during the PET/MRI scan with several other MR sequences. The DTI analysis along the perivascular space index (DTI-ALPS index) was calculated to estimate the functional activity of the glymphatic system. Centiloid scale was applied to quantify amyloid deposition levels from [ 11 C]PiB PET images. All patients in the AD group showed positive [ 11 C]PiB accumulation, whereas all CN participants were negative. ALPS-index for all subjects linearly correlated with PiB centiloid, MMSE scores, and hippocampal volume. The correlation between the ALPS-index and PiB accumulation was more pronounced than with any other biomarkers. These findings suggest that glymphatic system dysfunction is a significant factor in the early stages of Alzheimer's disease., (© 2024. The Author(s).)

The integrated positron emission tomography/magnetic resonance imaging (PET/MRI) scanner simultaneously acquires metabolic information via PET and morphological information using MRI. However, attenuation correction, which is necessary for quantitative PET evaluation, is difficult as it requires the generation of attenuation-correction maps from MRI, which has no direct relationship with the gamma-ray attenuation information. MRI-based bone tissue segmentation is potentially available for attenuation correction in relatively rigid and fixed organs such as the head and pelvis regions. However, this is challenging for the chest region because of respiratory and cardiac motions in the chest, its anatomically complicated structure, and the thin bone cortex. We propose a new method using unsupervised generative attentional networks with adaptive layer-instance normalisation for image-to-image translation (U-GAT-IT), which specialised in unpaired image transformation based on attention maps for image transformation. We added the modality-independent neighbourhood descriptor (MIND) to the loss of U-GAT-IT to guarantee anatomical consistency in the image transformation between different domains. Our proposed method obtained a synthesised computed tomography of the chest. Experimental results showed that our method outperforms current approaches. The study findings suggest the possibility of synthesising clinically acceptable computed tomography images from chest MRI with minimal changes in anatomical structures without human annotation., (© 2022. The Author(s).)

Purpose: To retrospectively assess the repeatability of physiological F-18 labeled fluorodeoxyglucose (FDG) uptake in the skin on positron emission tomography/magnetic resonance imaging (PET/MRI) and explore its regional distribution and relationship with sex and age., Methods: Out of 562 examinations with normal FDG distribution on whole-body PET/MRI, 74 repeated examinations were evaluated to assess the repeatability and regional distribution of physiological skin uptake. Furthermore, 224 examinations were evaluated to compare differences in the uptake due to sex and age. Skin segmentation on PET was performed as body-surface contouring on an MR-based attenuation correction map using an off-line reconstruction software. Bland-Altman plots were created for the repeatability assessment. Kruskal-Wallis test was performed to compare the maximum standardized uptake value (SUVmax) with regional distribution, age, and sex., Results: The limits of agreement for the difference in SUVmean and SUVmax of the skin were less than 30%. The highest SUVmax was observed in the face (3.09±1.04), followed by the scalp (2.07±0.53). The SUVmax in the face of boys aged 0-9 years and 10-20 years (1.33±0.64 and 2.05±1.00, respectively) and girls aged 0-9 years (0.98±0.38) was significantly lower than that of men aged ≥20 years and girls aged ≥10 years (p<0.001). In women, the SUVmax of the face (2.31±0.71) of ≥70-year-olds was significantly lower than that of 30-39-year-olds (3.83±0.82) (p<0.05)., Conclusion: PET/MRI enabled the quantitative analysis of skin FDG uptake with repeatability. The degree of physiological FDG uptake in the skin was the highest in the face and varied between sexes. Although attention to differences in body habitus between age groups is needed, skin FDG uptake also depended on age., Competing Interests: Takako Kurimoto is an employee of GE Healthcare (Hino, Tokyo, Japan). This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Purpose: Accurate prediction of post-hepatectomy liver failure (PHLF) is important in advanced hepatocellular carcinoma (HCC). We aimed to retrospectively evaluate the utility of gadoxetic acid-enhanced MRI for predicting PHLF in patients who underwent anatomic hepatectomy for HCC with portal vein invasion., Methods: Forty-one patients (32 men, 9 women) were included. Hepatobiliary-phase MR images were acquired 20 min after injection of gadoxetic acid using a 3D fat-suppressed T1-weighted spoiled gradient-echo sequence. Liver-spleen ratio (LSR), remnant hepatocellular uptake index (rHUI), and HUI were calculated. The severity of PHLF was defined according to the International Study Group of Liver Surgery. Differences in LSR between the resected liver and the remnant liver, and HUI and rHUI/HUI between no/mild and severe PHLF were compared using the Wilcoxon signed-rank test and Wilcoxon rank-sum test, respectively. Univariate and multivariate logistic regression analyses were performed to identify predictors of severe PHLF. Areas under the receiver operating characteristic curves (AUCs) of rHUI and rHUI/HUI were calculated for predicting severe PHLF., Results: Nine patients developed severe PHLF. LSR of the remnant liver was significantly higher than that of the resected liver (P < 0.001). Severe PHLF demonstrated significantly lower rHUI (P < 0.001) and rHUI/HUI (P < 0.001) compared with no/mild PHLF. Multivariate logistic regression analysis showed that decreased rHUI (P = 0.012, AUC=0.885) and rHUI/HUI (P = 0.002, AUC=0.852) were independent predictors of severe PHLF., Conclusion: Gadoxetic acid-enhanced MRI can be a promising noninvasive examination for assessing global and regional liver function, allowing estimation of the functional liver remnant and accurate prediction of severe PHLF before hepatic resection., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objectives: This study aimed to evaluate the diagnostic performance of the lung zero-echo time (ZTE) sequence in FDG PET/MRI for detection and differentiation of lung lesions in oncologic patients in comparison with conventional two-point Dixon-based MR imaging., Methods: In this single-institution retrospective study approved by the institutional review board, 209 patients with malignancies (97 men and 112 women; age range, 17-89 years; mean age, 66.5 ± 12.9 years) underwent 18 F-FDG PET/MRI between August 2017 and August 2018, with diagnostic Dixon and ZTE under respiratory gating acquired simultaneously with PET. Image analysis was performed for PET/Dixon and PET/ZTE fused images by two readers to assess the detectability and differentiation of lung lesions. The reference standard was pathological findings and/or the data from a chest CT. The detection and differentiation abilities were evaluated for all lesions and subgroups divided by lesion size and maximum standardized uptake value (SUVmax)., Results: Based on the reference standard, 227 lung lesions were identified in 113 patients. The detectability of PET/ZTE was significantly better than that of PET/Dixon for overall lesions, lesions with a SUVmax less than 3.0 and lesions smaller than 4 mm (p < 0.01). The diagnostic performance of PET/ZTE was significantly better than that of PET/Dixon for overall lesions and lesions smaller than 4 mm (p < 0.01)., Conclusions: ZTE can improve diagnostic performance in the detection and differentiation of both FDG-avid and non-FDG-avid lung lesions smaller than 4 mm in size, yielding a promising tool to enhance the utility of FDG PET/MRI in oncology patients with lung lesions., Key Points: • The detection rate of PET/ZTE for lesions with a SUVmax of less than 1.0 was significantly better than that of PET/Dixon. • The performance for differentiation of PET/ZTE for lesions that were even smaller than 4 mm in size were significantly better than that of PET/Dixon. • Inter-rater agreement of PET/ZTE for the differentiation of lesions less than 4 mm in size was substantial and better than that of PET/Dixon.

Radiation therapy is a useful treatment for tumors and vascular malformations of the central nervous system. Radiation therapy is associated with complications, including leukoencephalopathy, radiation necrosis, vasculopathy, and optic neuropathy. Secondary tumors are also often seen long after radiation therapy. Secondary tumors are often benign tumors, such as hemangiomas and meningiomas, but sometimes malignant gliomas and soft tissue sarcomas emerge. We review the imaging findings of complications that may occur after brain radiation therapy.

Objectives: This study was performed to assess the role of retrospective PET-MRI fusion with Ga-68-DOTA(0)-Phe(1)-Tyr(3)-octreotide (Ga-68-DOTATOC) PET and Gd-EOB-DTPA MRI in the detection of hepatic metastases from neuroendocrine tumours (NET)., Methods: Twenty-two consecutive patients with suspected liver metastases from histopathologically proven NET were examined with Gd-EOB-DTPA MRI and multiphase contrast-enhanced Ga-68-DOTATOC PET/CT. PET and MRI images were retrospectively fused using commercially available software. Two physicians experienced in nuclear medicine and radiology analysed the images to assess diagnostic confidence and characterise liver lesions., Results: A total of 181 lesions were detected. PET-MRI showed a sensitivity of 91.2% (significantly superior to PET/CT; P < 0.05) and a specificity of 95.6% (significantly superior to MRI; P < 0.05). PET/CT had a sensitivity of 73.5% and a specificity of 88.2%. MRI had a sensitivity of 87.6% and a specificity of 86.8%. The area under the curve was 0.98 for PET-MRI, 0.96 for MRI, and 0.89 for PET/CT (P < 0.05)., Conclusions: Retrospectively fused PET-MRI was superior to multiphase contrast-enhanced Ga-68-DOTATOC PET/CT and Gd-EOB-DTPA MRI in the detection of NET liver metastases. It was more sensitive than PET/CT and more specific than MRI. Fused PET-MRI therefore seems well suited for surgical and interventional treatment planning of NET liver metastases., Key Points: • Ga-68-DOTATOC PET-Gd-EOB-DTPA MRI fusion can improve imaging of liver metastases of neuroendocrine tumours. • This technique appears more sensitive than PET/CT for staging NET hepatic metastases. • Ga-68-DOTATOC PET-Gd-EOB-DTPA MRI fusion is more specific than MRI alone.

Purpose: The purpose of this study was to prospectively compare the efficacy of oxygen-enhanced MR imaging (O(2)-enhanced MRI) and CT for pulmonary functional loss assessment and clinical stage classification of asthmatics., Materials and Methods: O(2)-enhanced MRI, CT and %FEV(1) measurement were used 34 consecutive asthmatics classified into four stages ('Mild Intermittent [n=7]', 'Mild Persistent [n=8], 'Moderate Persistent [n=14]' and 'Severe Persistent [n=5]'). Relative enhancement ratio maps for every subject were generated, and determine mean relative enhancement ratios (MRERs). Mean lung density (MLD) and the airway wall area (WA) corrected by body surface area (WA/BSA) were also measured on CT. To compare the efficacy of the two methods for pulmonary functional loss assessment, all indexes were correlated with %FEV(1). To determine the efficacy of the two methods for clinical stage classification, all parameters for the four clinical stages were statistically compared., Results: %FEV(1) showed fair or moderate correlation with all parameters (0.15≤r(2)≤0.30, p<0.05). WA, WA/BSA and MRER of the 'Severe Persistent' group were significantly larger than those of 'Mild Intermittent' and 'Mild Persistent' groups (p<0.05), and MRER of the 'Moderate Persistent' group significantly lower than that of the 'Mild Intermittent' group (p<0.05)., Conclusion: O(2)-enhanced MRI is as effective as CT for pulmonary functional loss assessment and clinical stage classification of asthmatics., (Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To compare directly the capabilities of multidetector-row computed tomography (MDCT) and MRI for disease severity assessment and outcome prediction for acute pulmonary thromboembolism (APTE) patients., Materials and Methods: Fifty consecutive APTE patients underwent MDCT, MR angiography, dynamic perfusion MRI, treatment and follow-up examination. Pulmonary blood flow (PBF), pulmonary blood volume, and mean transit time maps were generated from perfusion MRI, and all segmental parameters were determined by using region of interest measurements. Receiver operator curve analyses were used to determine the most accurate parameter for diagnosis of the APTE segment. Then, APTE index from perfusion MRI (PE(perfusion MRI) index), right ventricle/left ventricle (RV/LV) diameter ratio and APTE indexes from embolic burdens observed on MDCT (PE(CT) index) and MR angiography (PE(MRA) index) were calculated. Finally, ability to differentiate mortality (n = 8) from survival (n = 42) groups and to predict patient outcome were statistically assessed., Results: PBF was a significantly more accurate parameter than others (P < 0.05). When feasible threshold value was applied, specificity and accuracy of RV/LV diameter ratio and PE(Perfusion MRI) index were significantly higher than those of PE(CT) and PE(MRA) indexes (P < 0.05). Logistic regression analysis demonstrated that each index was a significant predictor (P < 0.05)., Conclusion: Dynamic perfusion MRI can be effective for disease extent assessment and outcome prediction for APTE patients., (Copyright 2010 Wiley-Liss, Inc.)

Purpose: To compare the utility of phase contrast MR imaging (PC-MRI) for assessment of pulmonary flow and pressure estimation with that of right heart catheterization and echocardiography (cardiac US) in patients with pulmonary arterial hypertension (PAH)., Materials and Methods: Twenty consecutive patients with suspected PAH underwent PC-MRI, cardiac US, and right heart catheterization. In each patient, PC-MRI was acquired by cine 2D-PC method on a 1.5 Tesla scanner, and stroke volume (SV) and pulmonary arterial systolic pressure (PASP) were assessed by using the modified Bernoulli's equation. To evaluate the agreements of SV and PASP among the three methods, correlations and limits of agreement among the three methods were statistically assessed by using the Bland-Altman's analyses., Results: The correlations and limits of agreement for SV and PASP between PC-MRI and catheterization (r = 0.96, r(2) = 0.94, 1.1 +/- 6.9 mL and r = 0.94, r(2) = 0.88, -3.2 +/- 14.5 mmHg, respectively) were better than between cardiac US and catheterization (r = 0.01, r(2) < 0.01, 8.9 +/- 42.1 mL and r = 0.86, r(2) = 0.72, -5.9 +/- 27.7 mmHg, respectively)., Conclusion: PC-MRI is more compatible with right heart catheterization than cardiac US in pulmonary flow and pressure estimation.

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., ((c) 2009 Wiley-Liss, Inc.)

Purpose: To prospectively evaluate the capability of dynamic perfusion MRI for assessment of disease severity and progression to pulmonary arterial hypertension (PAH) in connective tissue disease (CTD) patients., Materials and Methods: In all, 18 gender- and age-matched CTD patients without and with PAH and nine healthy volunteers underwent dynamic perfusion MRI, Doppler echocardiography, and pulmonary function test. Disease severity of CTD was assessed in terms of diffusing capacity for carbon monoxide (%DL(CO)) and estimated systolic pulmonary arterial pressure (sPAP), and progression of PAH in terms of pulmonary arterial pressure (mPAP) and pulmonary vascular resistance (PVR). From calculated pulmonary perfusion parameter maps, means of pulmonary blood flow (mPBF), pulmonary blood volume (mPBV), and mean transit time (mMTT) were determined as averages of all region of interest (ROI) measurements. To determine disease severity in CTD, all parameters were statistically correlated with sPAP and %DL(CO). To determine progression to PAH, all parameters were statistically correlated with mPAP and PVR., Results: All pulmonary perfusion parameters correlated significantly with sPAP and % DL(CO) (P < 0.05). mPBF and mPBV correlated significantly with mPAP and moderately with PVR (P < 0.05)., Conclusion: Dynamic perfusion MRI can be used for assessment of disease severity and progression of PAH in CTD patients., ((c) 2008 Wiley-Liss, Inc.)

Purpose: To prospectively and directly compare the capability of whole-body diffusion-weighted (DW) imaging, whole-body magnetic resonance (MR) imaging with and that without DW imaging, and integrated fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) for M-stage assessment in non-small cell lung cancer (NSCLC) patients., Materials and Methods: The institutional review board approved this study; informed consent was obtained from patients. A total of 203 NSCLC patients (109 men, 94 women; mean age, 72 years) prospectively underwent whole-body DW imaging, whole-body MR imaging, and FDG PET/CT. Final diagnosis of the M-stage in each patient was determined on the basis of results of all radiologic and follow-up examinations. Two chest radiologists and two nuclear medicine physicians independently assessed all examination results and used a five-point visual scoring system to evaluate the probability of metastases. Final diagnosis based on each of the methods was made by consensus of two readers. Receiver operating characteristic (ROC) analysis was used to compare the capability for M-stage assessment among whole-body DW imaging, whole-body MR imaging with and that without DW imaging, and PET/CT on a per-patient basis. Sensitivity, specificity, and accuracy were compared with the McNemar test., Results: Area under ROC curve (A(z)) values of whole-body MR imaging with DW imaging (A(z) = 0.87, P = .04) and integrated FDG PET/CT (A(z) = 0.89, P = .02) were significantly larger than that of whole-body DW imaging (A(z) = 0.79). Specificity and accuracy of whole-body MR imaging with (specificity, P = .02; accuracy, P < .01) and that without DW imaging (specificity, P = .02; accuracy, P = .01) and integrated FDG PET/CT (specificity, P < .01; accuracy, P < .01) were significantly higher than those of whole-body DW imaging., Conclusion: Whole-body MR imaging with DW imaging can be used for M-stage assessment in NSCLC patients with accuracy as good as that of PET/CT.

Purpose: To compare the nodule management capabilities of dynamic MRI, dynamic multidetector-row computed tomography (MDCT) and coregistered positron emission tomography (PET)/CT., Materials and Methods: Dynamic MRI, dynamic MDCT, PET, microbacterial, and pathological examinations were administered to 175 consecutive patients with 202 nodules (<30 mm in diameter). The final diagnoses resulted in the classification of 202 nodules into two groups: requiring further intervention and treatment (N = 163) and no further evaluation (N = 39) groups. Maximum relative enhancement and slope of enhancement ratio were calculated as dynamic MR indices. Maximum enhancement, net enhancement, slope of enhancement, and absolute loss of enhancement were calculated as dynamic CT indices. maximum value of standard uptake value (SUV(max)) was measured on coregistered PET/CT. Receiver operating characteristics (ROC) analyses were performed to determine feasible threshold values for nodule management, and results were tested using McNemar's test., Results: When feasibility threshold values were adopted for nodule management, the specificity (82.1%) and accuracy (93.6%) of the slope of the enhancement ratio were significantly higher than those of dynamic CT indices (P < 0.05) and SUV(max) (P < 0.05)., Conclusion: Dynamic MRI can play a more specific and/or accurate role for nodule management as compared with dynamic MDCT and coregistered PET/CT., (2008 Wiley-Liss, Inc)

Objective: The purpose of the present study is to prospectively compare the capability of dynamic oxygen-enhanced MRI and quantitative CT for pulmonary functional loss assessment and clinical stage classification of smoking-related chronic obstructive pulmonary disease (COPD)., Subjects and Methods: Ten nonsmoking and 61 consecutive smoking-related COPD subjects underwent dynamic oxygen-enhanced MRI, CT, and pulmonary function tests. COPD subjects were classified into four clinical stages on the basis of the ATS-ERS guidelines. Wash-in time and relative enhancement ratio maps were generated by pixel-by-pixel analyses. Mean wash-in time and relative enhancement ratio were determined as averages of region of interest (ROI) measurements. CT-based functional lung volumes were measured on quantitative CT using the density-masked CT technique. For comparison of assessment capability for smoking-related functional loss, the three parameters were correlated with the percentage predicted forced expiratory volume in 1 second (%FEV1) and the percentage predicted diffusing capacity of the lung for carbon monoxide corrected for alveolar volume (%DL(CO)/VA). To determine the clinical stage classification capability, these parameters were statistically compared for nonsmoking subjects and all clinical stages of smoking-related COPD subjects., Results: Correlation between mean wash-in time and %FEV1 (r = -0.74, p < 0.0001) and between mean relative enhancement ratio and %DL(CO)/VA (r = 0.66, p < 0.0001) was better than that between CT-based functional lung volume and either %FEV1 (r = 0.61, p < 0.0001) or %DL(CO)/VA (r = 0.56, p < 0.0001). Mean wash-in time showed a significant difference between nonsmoking and smoking-related COPD subjects at all clinical stages (p < 0.05)., Conclusion: Dynamic oxygen-enhanced MRI has potential for pulmonary functional loss assessment and clinical stage classification of smoking-related COPD as does quantitative CT.

Purpose: To demonstrate the influence of inversion pulse type and inversion time for assessment of oxygen-enhancement on centrically-reordered non-slice-selective inversion-recovery (IR) half-Fourier single-shot turbo spin-echo (HASTE) sequence., Material and Methods: Phantoms with and without 100% oxygen and three healthy volunteers were studied with two-dimensional (2D) centrically-reordered non-slice selective IR-HASTE sequence with either composite or block inversion-recovery pulse at increasing inversion times from 200 to 1800 msec. Signal-to-noise ratios (SNRs) of phantom, real signal differences, and relative enhancement ratios of lung parenchyma between oxygen-enhanced and non-oxygen-enhanced MR images on composite and block pulse type were statistically compared at each TI., Results: SNRs at TIs of 200 and 400 msec using the composite inversion pulse type were significantly lower than those with the block inversion pulse in the in vivo study (P < 0.05), although no significant differences were observed in the phantom study and in the in vivo study at inversion times greater than or equal to 600 msec. Real signal intensity (SI) differences at 400 and 600 msec of the composite inversion pulse type were significantly higher than those with the block inversion pulse type (P < 0.05). Relative enhancement ratio at 800 msec with the composite inversion pulse were significantly lower than that with the block inversion pulse (P < 0.05)., Conclusion: IR pulse type and inversion time have influence on assessment of oxygen-enhancement by centrically-reordered non-slice-selective IR-HASTE sequence., ((c) 2007 Wiley-Liss, Inc.)

Purpose: To conduct a prospective comparison of the accuracy of whole-body MR imaging and positron emission tomography (PET) with fluorine-18 deoxyglucose (FDG) (FDG-PET) to assess the M-stage in lung cancer patients., Materials and Methods: A total of 90 consecutive lung cancer patients (mean age = 68 years) underwent whole-body MR imaging and FDG-PET as well as other standard radiological imaging procedures before and after treatment. Probabilities of metastases on whole-body MR imaging and FDG-PET were assessed by using 5-point scoring systems on a per-site basis and on a per-patient basis. Receiver operating characteristic (ROC) curve analysis was used to compare diagnostic capabilities. Sensitivity, specificity, and accuracy were also compared by using the McNemar's test on a per-site and per-patient basis., Results: For assessment of head and neck metastases and bone metastases, accuracies of whole-body MR imaging (95.0% and 94.8%, respectively) were significantly higher than those of FDG-PET (89.1% and 88.2%, respectively; P < 0.05). For assessment of the M-stage on a per-patient basis, accuracy of whole-body MR imaging (80.0%) was also significantly higher than that of FDG-PET (73.3%; P < 0.05)., Conclusion: Whole-body MR imaging is an accurate diagnostic technique and may be considered at least as effective as FDG-PET for assessment of the M-stage of lung cancer patients., ((c) 2007 Wiley-Liss, Inc.)

Purpose: To determine the appropriate concentration for quantitative assessment of dynamic contrast-enhanced pulmonary MR imaging., Materials and Methods: A total of 40 consecutive patients with small bronchioalveolar carcinoma underwent perfusion single-photon emission tomography (SPECT) and three-dimensional (3D) dynamic MR imaging with a 3D radiofrequency spoiled gradient-echo sequence. In each patient, 5 mL of contrast media with 0.1, 0.3, and 0.5 mmol/mL were administered at a rate of 5 mL/second. All patients were divided into two groups (<70 kg and > or =70 kg) for assessment of appropriate concentration to quantitatively assess regional perfusion parameter in routine clinical practice. Pulmonary blood flow (PBF) in each protocol was calculated from a signal intensity (SI)-time course curve. Differences and limits of agreement of PBF between dynamic MR imaging (PBF(MR)) using three different concentrations and perfusion SPECT (PBF(SPECT)) were statistically compared in both patient groups., Results: PBF(MR) using 0.3 mmol/mL in the <70-kg group and 0.5 mmol/mL in the > or =70-kg group showed no significant difference compared with PBF(SPECT) (P > 0.05). Limits of agreements in 0.3 mmol/mL in the <70-kg group and 0.5 mmol/mL in the > or =70-kg group were smaller than those of the other concentrations and small enough for clinical purposes., Conclusion: Appropriate concentrations provide accurate and reproducible assessments of regional pulmonary perfusion parameters on 3D dynamic MR perfusion imaging. We suggest using 5 mL of contrast media with 0.3 mmol/mL for patients weighing less than 70 kg and 0.5 mmol/mL for patients weighing 70 kg or more.

Objective: The purpose of this study was to determine whether quantitative pulmonary perfusion parameters obtained from 3D dynamic contrast-enhanced MR perfusion data can be used to assess the severity of primary pulmonary hypertension (PPH) as indicated by pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (MPAP)., Conclusion: Three-dimensional dynamic contrast-enhanced MRI has potential for assessment of disease severity as indicated by PVR and MPAP in patients with PPH.

Purpose: To prospectively determine if lung function as assessed with oxygen-enhanced magnetic resonance (MR) imaging correlates with postsurgical lung function in patients with lung cancer, as compared with quantitative and qualitative findings of computed tomography (CT) and scintigraphy., Materials and Methods: Study received institutional review board approval, and informed patient consent was obtained. Thirty consecutive patients (16 men and 14 women, aged 44-81 years; mean age, 65 years) considered candidates for lung resection underwent oxygen-enhanced MR imaging, CT, perfusion scintigraphy, and measurement of forced expiratory volume in 1 second (FEV1). A respiratory-synchronized inversion-recovery half-Fourier single-shot turbo spin-echo MR sequence was used for data acquisition. Correlation of postsurgical lung function (postsurgical FEV1) as determined with oxygen-enhanced MR imaging (FEV1MR), quantitative assessment with CT (FEV1Quant), qualitative assessment with CT (FEV1Qual), and perfusion scintigraphy (FEV1PS) was conducted with actual postsurgical FEV1, and the limits of agreement of each were determined with Bland-Altman analysis., Results: Correlation between postsurgical FEV1MR and actual postsurgical FEV1 values was excellent (r2= 0.81, P < .001); it was better than that of FEV1Qual (r2= 0.76) and FEV1PS (r2= 0.77) and similar to that of FEV1Quant (r2= 0.81) values. The limits of agreement of FEV1MR were between -9.9% and 10.9%., Conclusion: Oxygen-enhanced MR imaging can be used to predict posturgical lung function in patients with lung cancer, similar to quantitative CT.

Purpose: To determine the prognostic value of dynamic MRI for non-small-cell lung cancer (NSCLC) patients after chemoradiotherapy., Materials and Methods: A total of 114 consecutive patients with NSCLC underwent dynamic MRI after chemoradiotherapy. The patients were divided into two groups (local control (n=22) and local failure (n=92)) according to the presence of local recurrence. From the signal intensity-time course curve in each subject, the maximum relative enhancement ratio and slope of enhancement were calculated, and compared between two groups by Student's t-test. To determine the feasible threshold values of both MR indexes for group differentiation, ROC-based positive tests were performed. Finally, the Kaplan-Meier survival curves of each group divided by the adapted threshold value were compared by log-rank test., Results: The maximum relative enhancement ratio and the slope of enhancement in the local control group were significantly lower than those in the local failure group (P<0.05). Using 0.08/sec as the threshold value of the slope of enhancement, the sensitivity and specificity for differentiation between the two groups were 90.9% and 91.3%, respectively. When the slope of enhancement was adopted for estimation of prognosis after therapy, the mean survival period of the slope of enhancement0.08/sec (P<0.0001)., Conclusion: Dynamic MRI has potential prognostic value for NSCLC patients after chemoradiotherapy., (Copyright (c) 2005 Wiley-Liss, Inc.)

Purpose: To determine the utility of dynamic magnetic resonance imaging (MRI) in the differential subtyping of small adenocarcinomas of the lung., Materials and Methods: Twenty-nine pathologically diagnosed peripheral adenocarcinomas (less than 20 mm in diameter) underwent dynamic contrast-enhanced MRI. Maximum relative enhancement ratio, slope of enhancement, and corrected start time of enhancement were calculated from signal intensity-time curve of pulmonary lesion for each subject, and were statistically compared among bronchioloalveolar carcinoma (BAC) group (7 cases), mixed BAC group (10 cases), and adenocarcinoma group (12 cases)., Results: Maximum relative enhancement ratio (P<0.001) and slope of enhancement (P<0.001) of BAC group were significantly higher than those of mixed BAC and adenocarcinoma groups. Start times of BAC group were significantly earlier than those of mixed BAC (P=0.0001) and adenocarcinoma groups (P<0.0001). Adapting the thresholds values of MR indexes from the positive tests, sensitivity, specificity, positive predictive value, negative predictive value and accuracy for differentiating BAC from other subtypes were 85.7, 100.0, 100.0, 95.7, and 96.6%, respectively., Conclusions: Dynamic MRI is useful for differentiating subtypes of small peripheral adenocarcinoma.