Diagnostic value of whole-body MRI with diffusion-weighted sequence for detection of peritoneal metastases in colorectal malignancy

Objective：To assess the diagnostic accuracy of whole-body MRI using diffusion-weighted sequence（WB-DWI）to determine the peritoneal cancer index（PCI）in correlation with surgical and histopathological findings.Methods：Twenty-seven patients underwent preoperative WB-MRI,followed by cytoreductive surgery for primary tumors of the appendix（n=15）,colorectum（n=12）,and associated peritoneal disease.A total of 351 regions were retrospectively reviewed.The sensitivity,specificity,and accuracy were calculated at 13 anatomical sites.The WB-DWI PCI and PCI type were compared with surgical and histopathological findings.Results：No statistical difference was found between the WB-DWI PCI and surgical PCI（P=0.574）.WB-DWI correctly predicted the PCI type in 24 of 27 patients with high accuracy（88.9%）,including 10 of 10 patients with small-volume tumor,12 of 14 with moderate-volume tumor,and 2 of 3 with large-volume tumor.WB-DWI correctly depicted tumors in 163 of 203 regions,with 40false-negative and 23 false-positive regions.The overall sensitivity,specificity,and accuracy of WB-DWI for the detection of peritoneal tumors were 80.3%,84.5%,and 82.1%,respectively.For lesions＆lt;0.5 cm in diameter,WB-DWI demonstrated good sensitivity（69.4%）.Conclusions：WB-DWI accurately predicted PCI before surgery in patients undergoing evaluation for cytoreductive surgery.

Feasibility of similarity coefficient map for improving morphological evaluation of T_2* weighted MRI for renal cancer

The purpose of this paper is to investigate the feasibility of using a similarity coefficient map（SCM） in improving the morphological evaluation of T2＊ weighted（T2＊W） magnatic resonance imaging（MRI） for renal cancer.Simulation studies and in vivo 12-echo T2＊W experiments for renal cancers were performed for this purpose.The results of the first simulation study suggest that an SCM can reveal small structures which are hard to distinguish from the background tissue in T2＊W images and the corresponding T2＊ map.The capability of improving the morphological evaluation is likely due to the improvement in the signal-to-noise ratio（SNR） and the carrier-to-noise ratio（CNR） by using the SCM technique.Compared with T2＊ W images,an SCM can improve the SNR by a factor ranging from 1.87 to 2.47.Compared with T2＊ maps,an SCM can improve the SNR by a factor ranging from 3.85 to 33.31.Compared with T2＊W images,an SCM can improve the CNR by a factor ranging from 2.09 to 2.43.Compared with T2＊ maps,an SCM can improve the CNR by a factor ranging from 1.94 to 8.14.For a given noise level,the improvements of the SNR and the CNR depend mainly on the original SNRs and CNRs in T2＊W images,respectively.In vivo experiments confirmed the results of the first simulation study.The results of the second simulation study suggest that more echoes are used to generate the SCM,and higher SNRs and CNRs can be achieved in SCMs.In conclusion,an SCM can provide improved morphological evaluation of T2＊W MR images for renal cancer by unveiling fine structures which are ambiguous or invisible in the corresponding T2＊W MR images and T2＊ maps.Furthermore,in practical applications,for a fixed total sampling time,one should increase the number of echoes as much as possible to achieve SCMs with better SNRs and CNRs.

Prediction of radiosensitivity in primary central nervous system germ cell tumors using dynamic contrast-enhanced magnetic resonance imaging

Objective： To evaluate the feasibility of dynamic contrast-enhanced magnetic resonance imaging（DCEMRI） for predicting tumor response to radiotherapy in patients with suspected primary central nervous system（CNS） germ cell tumors（GCTs）.Methods： DCE-MRI parameters of 35 patients with suspected primary CNS GCTs were obtained prior to diagnostic radiation, using the Tofts and Kermode model. Radiosensitivity was determined in tumors diagnosed 2 weeks after radiation by observing changes in tumor size and markers as a response to MRI. Taking radiosensitivity as the gold standard, the cut-off value of DCE-MRI parameters was measured by receiver operating characteristic（ROC） curve. Diagnostic accuracy of DCE-MRI parameters for predicting radiosensitivity was evaluated by ROC curve.Results： A significant elevation in transfer constant（K^trans） and extravascular extracellular space（Ve）（P=0.000）, as well as a significant reduction in rate constant（Kep）（P=0.000） was observed in tumors. K^trans, relative K^trans, and relative Kep of the responsive group were significantly higher than non-responsive groups. No significant difference was found in Kep, Ve, and relative Ve between the two groups. Relative K^trans showed the best diagnostic value in predicting radiosensitivity with a sensitivity of 100%, specificity of 91.7%, positive predictive value（PPV） of 95.8%, and negative predictive value（NPV） of 100%.Conclusions： Relative K^trans appeared promising in predicting tumor response to radiation therapy（RT）. It is implied that DCE-MRI pre-treatment is a requisite step in diagnostic procedures and a novel and reliable approach to guide clinical choice of RT.

Prognostic Value of Feature-Tracking Circumferential Strain in Dilated Cardiomyopathy Patients with Severely Reduced Ejection Fraction Incremental to Late Gadolinium Enhancement

Myocardial fiber deformation measurements have been reported to be associated with adverse outcomes in patients with acute heart failure and those with myocardial infarction.However,few studies have addressed the prognostic value of global circumferential strain(GCS)in dilated cardiomyopathy(DCM)patients with severely impaired systolic function.This study aimed to evaluate the prognostic value of cardiac magnetic resonance(CMR)-derived GCS in DCM patients with severely reduced ejection.Consecutive DCM patients with severely reduced ejection fraction(EF<35%)who underwent CMR were included.GCS was calculated from CMR cine images.The clinical endpoint was a composite of all-cause mortality,heart transplantation,implantable cardioverter defibrillator(ICD)implantation and aborted sudden cardiac death(SCD).A total of 129 patients with a mean EF of 15.33%(11.36%–22.27%)were included.During a median follow-up of 518 days,endpoint events occurred in 50 patients.Patients with GCS≥the median(−5.17%)had significantly reduced event-free survival as compared with those with GCS<the median(P<0.01).GCS was independently associated with adverse events after adjusting for clinical and imaging risk factors including extent of late gadolinium enhancement(LGE)(P<0.05).Adding GCS into the model including the extent of LGE resulted in significant improvements in the C-statistic(from 0.706 to 0.742;P<0.05)with a continuous net reclassification improvement(NRI)of 29.71%.It was concluded that GCS derived from CMR could be useful for risk stratification in DCM patients with severely reduced EF,which may increase common imaging risk factors including LGE.

Coronary artery plaque imaging:Comparison of black-blood MRI and 64-multidetector computed tomography

Objective: To comparatively evaluate black-blood coronary arterial wall MRI and 64-multidetector computed tomography (64-MDCT) for detection and classification of coronary artery plaques. Methods: We included 15 patients with confirmed coronary artery plaques in the proximal or middle segments of coronary arteries by 64-MDCT, who underwent black-blood coronary wall MRI at 1.5 T within 10 days. Cross-sectional coronary wall images were acquired using a 2D double-inversion-recovery, electrocardiograph-triggered, navigator-gated, fat-suppressed, turbo-spin-echo sequence on the coronary arteries with lesions from the ostium to the middle segment continuously without gap. The vessel cross-sectional area (CSA), luminal CSA, maximal wall thickness, plaque burden, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) were measured in each slice and subsequently compared with computed tomography angiography (CTA) images. CTA images were divided into 5-mm segments for side-by-side comparison with MRI. Results: Of the 15 patients, 12 were enrolled in the study. Coronary plaques were found in 46 slices on both CTA and MRI. Plaques were classified to 3 groups based on CTA:calcified plaques (n ? 11), soft plaques (n ? 23), and mixed plaques (n ? 12). In MRI, the plaque burden, maximal wall thickness, SNR, and CNR in the coronary walls containing plaques were greater than in the normal coronary walls (0.83 ± 0.08 vs. 0.73 ± 0.08, 1.88 ± 0.51 vs. 1.51 ± 0.26 mm, 12.95 ± 2.78 vs. 9.93 ± 2.31, and 6.76 ± 2.52 vs. 3.89 ± 1.54, respectively;P<0.05). The luminal CSA at the plaque was smaller than in normal coronary walls (2.50 ± 1.50 vs. 4.72 ± 2.28 mm2;P<0.05). The SNR in the soft plaque was significantly greater than in calcified and mixed plaques (P<0.05). Conclusions: Coronary wall MRI can identify coronary plaques in the proximal and middle segments and has the potential to differentiate plaque types based on signal intensity.

The exploration of flow pattern in the superior vena cava of healthy adults:A 4D flow magnetic resonance imaging study

Our study sought to investigate the blood flow pattern in the superior vena cava(SVC)of healthy adults and to describe the development and characteristics of the flow pattern using 4D flow magnetic resonance imaging(MRI).4D flow MRI data with full coverage of SVC and brachiocephalic veins(BVs)were acquired with a 3-Testa MRI in thirty healthy adults(age:28.70±9.09).Hemodynamic parameters in the SVC,including velocity,velocity vector,flow visualization(pathlines,streamlines),flow waveform and energy loss,were obtained with specialized commercial post-processing software based on 4D flow MRI data.This study found that:(1)The SVC has a pulsating flow waveform with double peaks.(2)Based on BVs flow of the SVC pathline visualization,flow patterns could be divided into three development types:twining(n=14),untwining(n=)and no helical flow(n=7).(3)With the decreasing blood velocity,helical flow areas tended to gradually extend.(4)There were no significant differences in most hemodynamic parameters among the three types.The exploration of the blood flow characteristics of normal SVC may be the first step for capturing pathogenic features before the patients develop symptoms with a certain positive significance.The potential physiological significance of these phenomena deserves more exploration in future studies.