Aliphatic and Olefinic Fat Suppression in the Orbit Using Polarity-altered Spectral and Spatial Selective Acquisition (PASTA) with Opposed Phase.

PURPOSE: Fatty acid composition of the orbit makes it challenging to achieve complete fat suppression during orbit MR imaging. Implementation of a fat suppression technique capable of suppressing signals from saturated (aliphatic) and unsaturated (olefinic or protons at double-bonded carbon sites) fat would improve the visualization of an optical nerve. Furthermore, the ability to semi-quantify the fractions of aliphatic and olefinic fat may potentially provide valuable information in assessing orbit pathology. METHODS: A phantom study was conducted on various oil samples on a clinical 3 Tesla scanner. The imaging protocol included three 2D fast spin echo (FSE) sequences: in-phase, polarity-altered spectral and spatial selective acquisition (PASTA), and a combination of PASTA with opposed phase in olefinic and aliphatic chemical shift. The results were validated against high-resolution 11.7T NMR and compared with images acquired with spectral attenuated inversion recovery (SPAIR) and chemical shift selective (CHESS) fat suppression techniques. In-vivo data were acquired on eight healthy subjects and were compared with the prior histological studies. RESULTS: PASTA with opposed phase achieved complete suppression of fat signals in the orbits and provided images of well-delineated optical nerves and muscles in all subjects. The olefinic fat fraction in the olive, walnut, and fish oil phantoms at 3T was found to be 5.0%, 11.2%, and 12.8%, respectively, whereas 11.7T NMR provides the following olefinic fat fractions: 6.0% for olive, 11.5% for walnut, and 12.6% for fish oils. For the in-vivo study, on average, olefinic fat accounted for 9.9% ± 3.8% of total fat while the aliphatic fat fraction was 90.1% ± 3.8%, in the normal orbits. CONCLUSION: We have introduced a new fat suppression technique using PASTA with opposed phase and applied it to human orbits. The purposed method achieves an excellent orbital fat suppression and the quantification of aliphatic and olefinic fat signals.

Lung T2 * mapping using 3D ultrashort TE with tight intervals δTE.

PURPOSE: To develop 3D ultrashort-TE (UTE) sequences with tight TE intervals (δTE), allowing for accurate T 2 * $$ {\mathrm{T}}_2^{\ast } $$ mapping of lungs under free breathing. METHODS: We have implemented a four-echo UTE sequence with δTE (< 0.5 ms). A Monte-Carlo simulation was performed to identify an optimal number of echoes that would result in a significant improvement in the accuracy of the T 2 * $$ {\mathrm{T}}_2^{\ast } $$ fit within an acceptable scan time. A validation study was conducted on a phantom with known short T 2 * $$ {\mathrm{T}}_2^{\ast } $$ values (< 5 ms). The scanning protocol included a combination of a standard multi-echo UTE with six echoes (2.2-ms intervals) and a new four-echo UTE (TE < 2 ms) with tight TE intervals δTE. The human imaging was performed at 3 T on 6 adult volunteers. T 2 * $$ {\mathrm{T}}_2^{\ast } $$ mapping was performed with mono-exponential and bi-exponential models. RESULTS: The simulation for the proposed 10-echo acquisition predicted over 2-fold improvement in the accuracy of estimating the short T 2 * $$ {\mathrm{T}}_2^{\ast } $$ compared with the regular six-echo acquisition. In the phantom study, the T 2 * $$ {\mathrm{T}}_2^{\ast } $$ was measured up to three times more accurately compared with standard six-echo UTE. In human lungs, T 2 * $$ {\mathrm{T}}_2^{\ast } $$ maps were successfully obtained from 10 echoes, yielding average values T 2 * $$ {\mathrm{T}}_2^{\ast } $$ = 1.62 ± 0.48 ms for mono-exponential and T 2 s * $$ {\mathrm{T}}_{2s}^{\ast } $$ = 1.00 ± 0.53 ms for bi-exponential models. CONCLUSION: A UTE sequence using δTE was implemented and validated on short T 2 * $$ {\mathrm{T}}_2^{\ast } $$ phantoms. The sequence was successfully applied for lung imaging; the bi-exponential signal model fit for human lung imaging may provide valuable insights into the diseased human lungs.

Sex-specific associations in multiparametric 3 T MRI measurements in adult livers.

BACKGROUND: MRI relaxometry mapping and proton density fat fraction (PDFF) have been proposed for the evaluation of hepatic fibrosis. However, sex-specific relationships of age and body fat with these MRI parameters have not been studied in detail among adults without clinically manifest hepatic disease. We aimed to determine the sex-specific correlation of multiparametric MRI parameters with age and body fat and to evaluate their interplay associations. METHODS: 147 study participants (84 women, mean age 48±14 years, range 19-85 years) were prospectively enrolled. 3 T MRI including T1, T2 and T1ρ mapping and PDFF and R2* map were acquired. Visceral and subcutaneous fat were measured on the fat images from Dixon water-fat separation sequence. RESULTS: All MRI parameters demonstrated sex difference except for T1ρ. PDFF was more related to visceral than subcutaneous fat. Per 100 ml gain of visceral or subcutaneous fat is associated with 1 or 0.4% accretion of liver fat, respectively. PDFF and R2* were higher in men (both P = 0.01) while T1 and T2 were higher in women (both P < 0.01). R2* was positively but T1 and T2 were negatively associated with age in women (all P < 0.01), while T1ρ was positively related to age in men (P < 0.05). In all studies, R2* was positively and T1ρ was negatively associated with PDFF (both P <0.0001). CONCLUSION: Visceral fat plays an essential role in the elevated liver fat. When using MRI parametric measures for liver disease evaluation, the interplay between these parameters should be considered.

3D T1rho sequences with FASE, UTE, and MAPSS acquisitions for knee evaluation.

PURPOSE: For biochemical evaluation of soft tissues of the knee, T1rho magnetic resonance imaging (MRI) has been proposed. Purpose of this study was to compare three T1rho sequences based on fast advanced spin echo (FASE), ultrashort echo time (UTE), and magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots (MAPSS) acquisitions for the knee evaluation. MATERIALS AND METHODS: We developed two T1rho sequences using 3D FASE or 3D radial UTE acquisitions. 3D MAPSS T1rho was provided by the manufacturer. Agarose phantoms with varying concentrations were imaged. Additionally, bilateral knees of asymptomatic subjects were imaged sagittally. T1rho values of the phantoms and 4 regions of interest (ROI) of the knees (i.e., anterior and posterior meniscus, femoral and tibial cartilage) were determined. RESULTS: In phantoms, all T1rho values monotonically decreased with increasing agarose concentration. 3D MAPSS T1rho values of 51, 34, and 38 ms were found for 2, 3, and 4% agarose, respectively, similar to published values on another platform. In the knee, the raw images were detailed with good contrast. Cartilage and meniscus T1rho values varied with the pulse sequence, being the lowest in the 3D UTE T1rho sequence. Comparing different ROIs, menisci generally had lower T1rho values compared to cartilage, as expected in healthy knees. CONCLUSION: We have successfully developed and implemented the new T1rho sequences and validated them using agarose phantoms and volunteer knees. All sequences were optimized to be clinically feasible (~ 5 min or less) and yielded satisfactory image quality and T1rho values consistent with the literature.

The mechanisms of arterial signal intensity profile in non-contrast coronary MRA (NC-MRCA): a 3D printed phantom investigation and clinical translations.

Signal intensity (SI) drop has been proposed as an indirect stenosis assessment in non-contrast coronary MRA (NC-MRCA) but it uses unproven assumptions. We aimed to clarify the mechanisms that govern the SI in vitro and develop a stenosis detection method in vivo. Flow phantom tubes with/without stenosis were scanned under two spatial resolutions (0.5/1.0 mm3) on a 3.0 T MRI. Thirty-two coronary arteries from 11 volunteers were prospectively scanned with an EKG- and respiratory-gated 3D NC-MRCA with a resolution of 1.0 mm3, with coronary computed tomography angiography (CTA) as reference. The normalized SI along the centerline of the tubes or the coronary arteries was assessed against the distance from the orifice using a linear regression model. Its coefficient (SI decay slope) and goodness-of-fit (R2) were extracted to assess the effect of flow velocity and stenosis on the SI profile curve. The R2 was utilized for the stenosis detection. Phantom study: A slow flow velocity caused a steep SI decay slope. The SI drop revealed only at the inlet and outlet of stenosis due to the flow turbulence/vortex and yielded low R2, in which shape changed by the resolution. Clinical study: The R2 cutoff to detect ≥ 50% stenosis for the left and right coronary arteries were 0.64 and 0.20 with a sensitivity/specificity of 71.5/71.5 and 66.7/100 (%), respectively. The SI drop did not reflect the actual stenosis position and not suitable for the stenosis localization. The R2 cutoff represents an alternative method to detect stenoses on NC-MRCA at vessel level.Trial registration: ClinicalTrials.gov; NCT03768999, registered on December 7, 2018.

Computed DWI MRI Results in Superior Capability for N-Stage Assessment of Non-Small Cell Lung Cancer Than That of Actual DWI, STIR Imaging, and FDG-PET/CT.

BACKGROUND: Computed diffusion-weighted imaging (cDWI) is a mathematical computation technique that generates DWIs for any b-value by using actual DWI (aDWI) data with at least two different b-values and may improve differentiation of metastatic from nonmetastatic lymph nodes. PURPOSE: To determine the appropriate b-value for cDWI to achieve a better diagnostic capability for lymph node staging (N-staging) in non-small cell lung cancer (NSCLC) patients compared to aDWI, short inversion time (TI) inversion recovery (STIR) imaging, or positron emission tomography with 2-[fluorine-18] fluoro-2-deoxy-d-glucose combined with computed tomography (FDG-PET/CT). STUDY TYPE: Prospective. SUBJECTS: A total of 245 (127 males and 118 females; mean age 72 years) consecutive histopathologically confirmed NSCLC patients. FIELD STRENGTH/SEQUENCE: A 3 T, half-Fourier single-shot turbo spin-echo sequence, electrocardiogram (ECG)-triggered STIR fast advanced spin-echo (FASE) sequence with black blood and STIR acquisition and DWI obtained by FASE with b-values of 0 and 1000 sec/mm2 . ASSESSMENT: From aDWIs with b-values of 0 and 1000 (aDWI1000 ) sec/mm2 , cDWI using 400 (cDWI400 ), 600 (cDWI600 ), 800 (cDWI800 ), and 2000 (cDWI2000 ) sec/mm2 were generated. Then, 114 metastatic and 114 nonmetastatic nodes (mediastinal and hilar lymph nodes) were selected and evaluated with a contrast ratio (CR) for each cDWI and aDWI, apparent diffusion coefficient (ADC), lymph node-to-muscle ratio (LMR) on STIR, and maximum standard uptake value (SUVmax ). STATISTICAL TESTS: Receiver operating characteristic curve (ROC) analysis, Youden index, and McNemar's test. RESULTS: Area under the curve (AUC) of CR600 was significantly larger than the CR400 , CR800 , CR2000 , aCR1000 , and SUVmax . Comparison of N-staging accuracy showed that CR600 was significantly higher than CR400 , CR2000 , ADC, aCR1000 , and SUVmax , although there were no significant differences with CR800 (P = 0.99) and LMR (P = 0.99). DATA CONCLUSION: cDWI with b-value at 600 sec/mm2 may have potential to improve N-staging accuracy as compared with aDWI, STIR, and PET/CT. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Ultrafast lumbar spine MRI protocol using deep learning-based reconstruction: diagnostic equivalence to a conventional protocol.

OBJECTIVE: To evaluate the diagnostic equivalency between an ultrafast (1 min 53 s) lumbar MRI protocol using deep learning-based reconstruction and a conventional lumbar MRI protocol (12 min 31 s). MATERIALS AND METHODS: This study included 58 patients who underwent lumbar MRI using both conventional and ultrafast protocols, including sagittal T1-weighted, T2-weighted, short-TI inversion recovery, and axial T2-weighted sequences. Compared with the conventional protocol, the ultrafast protocol shortened the acquisition time to approximately one-sixth. To compensate for the decreased signal-to-noise ratio caused by the acceleration, deep learning-based reconstruction was applied. Three neuroradiologists graded degenerative changes and analyzed for presence of other pathologies. For the grading of degenerative changes, interprotocol intrareader agreement was assessed using kappa statics. Interchangeability between the two protocols was also tested by calculating the individual equivalence index between the intraprotocol interreader agreement and interprotocol interreader agreement. For the detection of other pathologies, interprotocol intrareader agreement was assessed. RESULTS: For the grading of degenerative changes, the kappa values for interprotocol intrareader agreement of all three readers ranged from 0.707 to 0.804, indicating substantial to almost perfect agreement. Except for foraminal stenosis and disc contour on axial images, the 95% confidence interval of the individual equivalence index was < 5%, indicating the two protocols were interchangeable. For the detection of other pathologies, the interprotocol intrareader agreement rates were > 98% for each individual pathology. CONCLUSIONS: Our proposed ultrafast lumbar spine MRI protocol provided almost equivalent diagnostic results to that of the conventional protocol, except for some degenerative changes.

Evaluation of liver T1 using MOLLI gradient echo readout under the influence of fat.

BACKGROUND: The effect of hepatic steatosis on the gradient-echo (GRE) based Modified Look-Locker Inversion Recovery (MOLLI) technique for T1 mapping has not been evaluated. The purpose of this study was to evaluate a GRE based MOLLI technique for hepatic T1 mapping and determine the relationship of T1 differences (ΔT1) on in-phase (IP) and out-of-phase (OP) to fat fraction (FF) measurement. MATERIALS AND METHODS: 3 T MRI included MOLLI T1 mapping with TE = 1.3 (OP), 2.4 (IP), and 1.8 ms, and chemical-shift-encoded sequence with spectral modeling of fat to generate FF map as a reference. Bloch simulations and oil/water phantoms were used to characterize the response of the MOLLI T1 in various FF < 30% since MOLLI T1 estimation was erratic beyond this limit. Curve fit between ΔT1 and FF from simulation was applied to validate the phantom and the in-vivo results. Thirty-eight normal volunteers were included (16 women, Age 44 ± 12 years, BMI 27 ± 5.3 kg/m2). MOLLI water images were reconstructed by the average of OP and IP images, and the T1 values on water images served as the reference for T1 bias calculation defined as the percent difference between OP, IP, TE = 1.8 ms and the referenced water T1. Linear regression was performed to correlate the FF quantified by the reference and MOLLI methods. RESULTS: Phantom results were consistent with the Bloch simulations. The simulated relationship between FF (0-30%) and ΔT1 could be modeled precisely by a cubic equation with R2 = 1. In-vivo MOLLI ΔT1 and estimated FF were correlated to the reference FF (both R2 ≥ 0.96 and P < 0.001). TE = 1.8 ms demonstrated less T1 bias (-1.34%) compared to TE = OP (5.32%) or IP (-3.8%, both P < 0.001). CONCLUSION: At 3 T, TE of 1.8 ms can be used to reduce the T1 bias and deliver consistent T1 values when FF is <30%.

Applicability of deep learning-based reconstruction trained by brain and knee 3T MRI to lumbar 1.5T MRI.

BACKGROUND: Several deep learning-based methods have been proposed for addressing the long scanning time of magnetic resonance imaging. Most are trained using brain 3T magnetic resonance images, but is unclear whether performance is affected when applying these methods to different anatomical sites and at different field strengths. PURPOSE: To validate the denoising performance of deep learning-based reconstruction method trained by brain and knee 3T magnetic resonance images when applied to lumbar 1.5T magnetic resonance images. MATERIAL AND METHODS: Using a 1.5T scanner, we obtained lumber T2-weighted sequences in 10 volunteers using three different scanning times: 228 s (standard), 119 s (double-fast), and 68 s (triple-fast). We compared the images obtained by the standard sequence with those obtained by the deep learning-based reconstruction-applied faster sequences. RESULTS: Signal-to-noise ratio values were significantly higher for deep learning-based reconstruction-double-fast than for standard and did not differ significantly between deep learning-based reconstruction-triple-fast and standard. Contrast-to-noise ratio values also did not differ significantly between deep learning-based reconstruction-triple-fast and standard. Qualitative scores for perceived signal-to-noise ratio and overall image quality were significantly higher for deep learning-based reconstruction-double fast and deep learning-based reconstruction-triple-fast than for standard. Average scores for sharpness, contrast, and structure visibility were equal to or higher for deep learning-based reconstruction-double-fast and deep learning-based reconstruction-triple-fast than for standard, but the differences were not statistically significant. The average scores for artifact were lower for deep learning-based reconstruction-double-fast and deep learning-based reconstruction-triple-fast than for standard, but the differences were not statistically significant. CONCLUSION: The deep learning-based reconstruction method trained by 3T brain and knee images may reduce the scanning time of 1.5T lumbar magnetic resonance images by one-third without sacrificing image quality.

3D Oxygen-Enhanced MRI at 3T MR System: Comparison With Thin-Section CT of Quantitative Capability for Pulmonary Functional Loss Assessment and Clinical Stage Classification of COPD in Smokers.

BACKGROUND: Oxygen (O2 )-enhanced MRI is mainly performed by a 2D sequence using 1.5T MR systems but trying to be obtained by a 3D sequence using a 3T MR system. PURPOSE: To compare the capability of 3D O2 -enhanced MRI and that of thin-section computed tomography (CT) for pulmonary functional loss assessment and clinical stage classification of chronic obstructive pulmonary disease (COPD) in smokers. STUDY TYPE: Prospective study. POPULATION: Fifty six smokers were included. FIELD STRENGTH/ SEQUENCE: 3T, 3D O2 -enhanced MRIs were performed with a 3D T1 -weighted fast field echo pulse sequence using the multiple flip angles. ASSESSMENTS: Smokers were classified into four stages ("Without COPD," "Mild COPD," "Moderate COPD," "Severe or very severe COPD"). Maps of regional changes in T1 values were generated from O2 -enhanced MR data. Regions of interest (ROIs) were then placed over the lung on all slices and averaged to determine mean T1 value change (ΔT1 ). Quantitative CT used the percentage of low attenuation areas within the entire lung (LAA%). STATISTICAL TESTS: ΔT1 and LAA% were correlated with pulmonary functional parameters, and compared for four stages using Tukey's Honestly Significant Difference test. Discrimination analyses were performed and McNemar's test was used for a comparison of the accuracy of the indexes. RESULTS: There were significantly higher correlations between ΔT1 and pulmonary functional parameters (-0.83 ≤ r ≤ -0.71, P < 0.05) than between LAA% and the same pulmonary functional parameters (-0.76 ≤ r ≤ -0.69, P < 0.05). ΔT1 and LAA% of the "Mild COPD" and "Moderate COPD" groups were significantly different from those of the "Severe or Very Severe COPD" group (P < 0.05). Discriminatory accuracy of ΔT1 (62.5%) and ΔT1 with LAA% (67.9%) was significantly greater than that of LAA% (48.2%, P < 0.05). DATA CONCLUSION: Compared with thin-section CT, 3D O2 -enhanced MRI has a similar capability for pulmonary functional assessment but better potential for clinical stage classification in smokers. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 1.

Ultrashort echo time time-spatial labeling inversion pulse magnetic resonance angiography with denoising deep learning reconstruction for the assessment of abdominal visceral arteries.

Current contrast-enhanced magnetic resonance angiography (MRA) and non-contrast-enhanced balanced steady-state free precession (bSSFP) MRA cause susceptibility artifacts from metallic devices in assessing endovascular visceral-artery interventions. The aims of this study are to investigate and compare image quality (IQ) and susceptibility artifacts of three-dimensional (3D) ultrashort echo time (UTE) time-spatial labeling inversion pulse (Time-SLIP) with those of 3D bSSFP Time-SLIP and to assess denoising deep learning reconstruction (dDLR) for the improvement of the signal-to-noise ratio (SNR) in 3D UTE with sparse sampling in phantoms and human subjects. This is a prospective type of study. Pulsatile glycerin-water flow phantom with platinum-tungsten-alloy coil, stainless-steel, nitinol, and cobalt-alloy stents were used. Ten healthy volunteers (seven males) and three patients (two males) were included in this study. 3D UTE Time-SLIP and 3D bSSFP Time-SLIP at 3T were used. The phantom-based study compared the signal-intensity ratio of the device levels (SRdevice ) and distal segments (SRdistal ) to the proximal segments. The volunteer-based study measured SNR, contrast ratio (CR), and IQ. The patient study evaluated local artifacts from metallic devices. Statistical tests included paired t-tests, Wilcoxon-signed rank tests, and Kruskal-Wallis tests. In the phantom-based study, SRdevice was small with UTE Time-SLIP, except the stainless-steel stent. SRdistal was greater (49.1%-90.4%) on bSSFP images than UTE images (-11.1% to 9.6%). Among volunteers, dDLR in UTE images improved SNR (p < 0.05) and IQ (p < 0.05), but CR was unaffected. UTE Time-SLIP showed inferior SNR and IQ than bSSFP Time-SLIP in images with and without dDLR (p < 0.05 for each). However, among patients, UTE Time-SLIP showed reduced metal artifacts compared to bSSFP Time-SLIP. Irrespective of the lower SNR and IQ of 3D UTE Time-SLIP than those of 3D bSSFP Time-SLIP, the former appeared to better depict flow after stenting or coiling. This indicates the potential of 3D UTE Time-SLIP to provide suitable diagnostic images of target vessels. dDLR improved SNR with reducing artifacts related to radial sampling, while maintaining the contrast. LEVEL OF EVIDENCE: 2. TECHNICAL EFFICACY STAGE: 2.

Non-contrast coronary magnetic resonance angiography: current frontiers and future horizons.

Coronary magnetic resonance angiography (coronary MRA) is advantageous in its ability to assess coronary artery morphology and function without ionizing radiation or contrast media. However, technical limitations including reduced spatial resolution, long acquisition times, and low signal-to-noise ratios prevent it from clinical routine utilization. Nonetheless, each of these limitations can be specifically addressed by a combination of novel technologies including super-resolution imaging, compressed sensing, and deep-learning reconstruction. In this paper, we first review the current clinical use and motivations for non-contrast coronary MRA, discuss currently available coronary MRA techniques, and highlight current technical developments that hold unique potential to optimize coronary MRA image acquisition and post-processing. In the final section, we examine the various research-based coronary MRA methods and metrics that can be leveraged to assess coronary stenosis severity, physiological function, and atherosclerotic plaque characterization. We specifically discuss how such technologies may contribute to the clinical translation of coronary MRA into a robust modality for routine clinical use.

Cardiovascular ultrashort echo time to map fibrosis-promises and challenges.

Increased collagen, or fibrosis, is an important marker of disease and may improve identification of patients at risk. In addition, fibrosis imaging may play an increasing role in guiding therapy and monitoring its effectiveness. MRI is the most frequently used modality to detect, visualize and quantify fibrosis non-invasively. However, standard MRI techniques used to phenotype cardiac fibrosis such as delayed enhancement and extracellular volume determination by T1 mapping, require the administration of gadolinium-based contrast and are particularly difficult to use in patients with cardiac devices such as pacemakers and automatic defibrillators. Therefore, such methods are limited in the serial evaluation of cardiovascular fibrosis as part of chronic disease monitoring. A method to directly measure collagen amount could be of great clinical benefit. In the current review we will discuss the potential of a novel MR technique, ultrashort echo time (UTE) MR, for fibrosis imaging. Although UTE imaging is successfully applied in other body areas such as musculoskeletal applications, there is very limited experience so far in the heart. We will review the established methods and currently available literature, discuss the technical considerations and challenges, show preliminary in vivo images and provide a future outlook on potential applications of cardiovascular UTE.

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.

Diffusion-weighted MR imaging using FASE sequence for 3T MR system: Preliminary comparison of capability for N-stage assessment by means of diffusion-weighted MR imaging using EPI sequence, STIR FASE imaging and FDG PET/CT for non-small cell lung cancer patients.

PURPOSE: To prospectively compare the diagnostic capability of diffusion-weighted MR imaging obtained with fast advantage spin-echo sequence (FASE-DWI) and echo planar imaging sequence (EPI-DWI), short inversion time inversion recovery fast advanced spin-echo (STIR FASE) imaging and FDG PET/CT for N-stage assessment of non-small cell carcinoma (NSCLC) patients. MATERIALS AND METHODS: 95 consecutive operable NSCLC patients underwent STIR FASE imaging, FASE-DWI and EPI-DWI with a 3T system, integrated PET/CT, surgical treatment and pathological and follow-up examinations. Probability of lymph node metastasis was visually assessed using a 5-point visual scoring system. ROC analyses were used to compare diagnostic capability of all methods, while their diagnostic performance was also compared by means of McNemar's test on a per node basis. Finally, McNemar's test was also used for statistical comparison of accuracy of N-stage assessment. RESULTS: Areas under the curve (Azs) for STIR FASE imaging (Az=0.95) and FASE-DWI (Az=0.92) were significantly larger than those for EPI-DWI (Az=0.78; p<0.0001 for STIR FSE imaging and FASE-DWI) and PET/CT (Az=0.85; p=0.0001 for STIR FSE imaging, p=0.03 for FASE-DWI) on a per node basis analysis. Accuracy of N-stage assessment using STIR FASE imaging (84.2% [80/95]) and FASE-DWI (83.2% [79/95]) was significantly higher than that using EPI-DWI (76.8% [73/95]; p=0.02 for STIR FASE imaging, p=0.03 for FASE-DWI) and PET/CT (73.7% [70/95]; p=0.002 for STIR FSE imaging, p=0.004 for FASE-DWI). CONCLUSION: Qualitative N-stage assessments of NSCLC patients obtained with FASE-DWI as well as STIR FASE imaging are more sensitive and/or accurate than those obtained with EPI-DWI and FDG PET/CT.

3D ECG- and respiratory-gated non-contrast-enhanced (CE) perfusion MRI for postoperative lung function prediction in non-small-cell lung cancer patients: A comparison with thin-section quantitative computed tomography, dynamic CE-perfusion MRI, and perfusion scan.

PURPOSE: To compare predictive capabilities of non-contrast-enhanced (CE)- and dynamic CE-perfusion MRIs, thin-section multidetector computed tomography (CT) (MDCT), and perfusion scan for postoperative lung function in non-small cell lung cancer (NSCLC) patients. MATERIALS AND METHODS: Sixty consecutive pathologically diagnosed NSCLC patients were included and prospectively underwent thin-section MDCT, non-CE-, and dynamic CE-perfusion MRIs and perfusion scan, and had their pre- and postoperative forced expiratory volume in one second (FEV1 ) measured. Postoperative percent FEV1 (po%FEV1 ) was then predicted from the fractional lung volume determined on semiquantitatively assessed non-CE- and dynamic CE-perfusion MRIs, from the functional lung volumes determined on quantitative CT, from the number of segments observed on qualitative CT, and from uptakes detected on perfusion scans within total and resected lungs. Predicted po%FEV1 s were then correlated with actual po%FEV1 s, which were %FEV1 s measured postoperatively. The limits of agreement were also determined. RESULTS: All predicted po%FEV1 s showed significant correlation (0.73 ≤ r ≤ 0.93, P < 0.0001) and limits of agreement with actual po%FEV1 (non-CE-perfusion MRI: 0.3 ± 10.0%, dynamic CE-perfusion MRI: 1.0 ± 10.8%, perfusion scan: 2.2 ± 14.1%, quantitative CT: 1.2 ± 9.0%, qualitative CT: 1.5 ± 10.2%). CONCLUSION: Non-CE-perfusion MRI may be able to predict postoperative lung function more accurately than qualitatively assessed MDCT and perfusion scan.