T1-weighted Postcontrast Sequences Research Articles

MRI-Based Evaluation of the Flexor Digitorum Superficialis Anatomy: Investigating the Prevalence and Morphometry of the "Chiasma Antebrachii".

Recent dissection studies resulted in the introduction of the term "chiasma antebrachii", which represents an intersection of the flexor digitorum superficialis (FDS) tendons for digits 2 and 3 in the distal third of the forearm. This retrospective investigation aimed to provide an MRI-based morphologic analysis of the chiasma antebrachii. In 89 patients (41 women, 39.3 ± 21.3 years), MRI examinations of the forearm (2010-2021) were reviewed by two radiologists, who evaluated all studies for the presence and length of the chiasma as well as its distance from the distal radioulnar and elbow joint. The chiasma antebrachii was identified in the distal third of the forearm in 88 patients (98.9%), while one intersection was located more proximally in the middle part. The chiasma had a median length of 28 mm (interquartile range: 24-35 mm). Its distances to the distal radioulnar and elbow joint were 16 mm (8-25 mm) and 215 mm (187-227 mm), respectively. T1-weighted post-contrast sequences were found to be superior to T2- or proton-density-weighted sequences in 71 cases (79.8%). To conclude, the chiasma antebrachii is part of the standard FDS anatomy. Knowledge of its morphology is important, e.g., in targeted injections of therapeutics or reconstructive surgery.

Diagnostic value of gadolinium contrast administration for spinal cord magnetic resonance imaging in multiple sclerosis patients and correlative markers of lesion enhancement

BackgroundMagnetic resonance imaging is essential for monitoring people with multiple sclerosis, but the diagnostic value of gadolinium contrast administration in spine magnetic resonance imaging is unclear.ObjectiveTo assess the diagnostic value of gadolinium contrast administration in spine magnetic resonance imaging follow-up examinations and identify imaging markers correlating with lesion enhancement.MethodsA total of 65 multiple sclerosis patients with at least 2 spinal magnetic resonance imaging follow-up examinations were included. Spine magnetic resonance imaging was performed at 3 Tesla with a standardized protocol (sagittal and axial T2-weighted turbo spin echo and T1-weighted post-contrast sequences). T2 lesion load and enhancing lesions were assessed by two independent neuroradiologists for lesion size, localization, and T2 signal ratio (T2 signallesion/T2 signalnormal appearing spinal cord).ResultsA total of 68 new spinal T2 lesions and 20 new contrast-enhancing lesions developed during follow-up. All enhancing lesions had a discernable correlate as a new T2 lesion. Lesion enhancement correlated with a higher T2 signal ratio compared to non-enhancing lesions (T2 signal ratio: 2.0 ± 0.4 vs. 1.4 ± 0.2, ****p < 0.001). Receiver operating characteristics analysis showed an optimal cutoff value of signal ratio 1.78 to predict lesion enhancement (82% sensitivity and 97% specificity).ConclusionGadolinium contrast administration is dispensable in follow-up spine magnetic resonance imaging if no new T2 lesions are present. Probability of enhancement correlates with the T2 signal ratio.

Detection of Crohn's disease with diffusion images versus contrast-enhanced images in pediatric using MR enterography with histopathological correlation.

The purpose of this study was to determine whether MRE performed with diffusion-weighted imaging (DWI) sequences is comparable to contrast-enhanced MRE in the detection of active small-bowel inflammation in pediatric patients with Crohn's disease (CD). We included in our study 68 patients with diagnosis of CD between April 2015 and June 2018 that underwent MRE examination. Examination protocol includes coronal and axial FISP, T2-w half-Fourier RARE and DWI sequences, a baseline coronal T1-w fat-saturated ultrafast (GRE) sequence followed by contrast 3D T1-w GRE. All images were assessed by two radiologists who graded each of bowel segments for the presence of inflammation on a four-point confidence scale on the basis of wall thickening and wall signal on DWI and ADC maps and comparing their results with post-contrast images. When considering all bowel segments, we found 41 true positive and 25 true negative on DWI. One false positive case corresponded to the absence of inflammatory histopathology changes at the level of the terminal ileum in a 15-year-old male, and one false negative case was in a 10-year-old female with only jejunal lesion. The corresponding sensitivity, specificity, PPV, NPV and accuracy were 97.6% (95% CI 67.7-99.7), 96.1% (95% CI 66.7-98.5), 97.6% (95% CI 70.8-98.4), 96.1% (95% CI 64.2-90.6) and 97% (95% CI 84.2-97.5), respectively. Analyzing the gadolinium-enhanced set, 35 true positive and 25 true negative results were found. One false positive case was found, and it was the same as with DWI. The corresponding sensitivity, specificity, PPV, NPV and accuracy were 83.3% (95% CI 65.9-86.7), 96.1% (95% CI 68.7-88.9), 97.2% (95% CI 84.3-98.7), 78.1% (95% CI 27.9-72.1) and 88.2% (95% CI 41.2-85.6), respectively. Sensitivity for the detection of active IBD lesion was significantly better with DWI than with CE-T1-w imaging (p = 0.002), whereas the specificity was similar (p = 0.743). Our study has shown that DWI sequences have a high accuracy in detecting the bowel segment affected by CD. These results emphasize the utility to include the DWI/ADC in standard MR enterography protocols and suggest that DWI could replace T1-weighted post-contrast sequences.

Longitudinal Imaging of Tumor Volume, Diffusivity, and Perfusion After Preoperative Endovascular Embolization in Supratentorial Hemispheric Meningiomas

To describe longitudinal image changes in supratentorial hemispheric meningiomas based on magnetic resonance imaging after preoperative embolization using calibrated microspheres. A total of 14 patients with symptomatic supratentorial meningiomas were included in a prospective, mono-centric, mono-arm study. Magnetic resonance imaging changes on diffusion-weighted imaging, dynamic contrast susceptibility-perfusion-weighted imaging, susceptibility-weighted imaging, and magnetization-prepared rapid acquisition gradient-echo sequence T1-weighted postcontrast sequences 6 and 48 hours after embolization were evaluated and correlated with angiographic and clinical data. The mean age of the patients was 63 ± 12.7 years with an equal female/male ratio. Twelve meningiomas were World Health Organization grade I and II tumors. After embolization, baseline apparent diffusion coefficient (901 ± 166 mm2/s) decreased significantly within 6 hours (696 ± 115 mm2/s, P= 0.0008) as well within 48 hours (752 ± 134 mm2/s; P= 0.0147). Baseline mean ratio of relative cerebral blood volume (rCBV)tumor/rCBVwhite matter (3.67 ± 1.83) and relative cerebral blood flow (rCBF)tumor/rCBFwhite matter (2.89 ± 1.57) significantly decreased after embolization within 6 hours (rCBVtumor/rCBVwhite matter of 1.45 ± 0.9; P= 0.0007, rCBF of 1.16 ± 0.68; P= 0.0029) and 48 hours (rCBV of 1.50 ± 1.07; P=0.0009, rCBFtumor/rCBFwhite matter of 1.19 ± 0.8; P=0.003). The viable enhanced baseline mean tumor volume (54.3 ± 34.9 mm3) was sustainably and significantly diminished within 6 hours (26.6 ± 20.8 mm3; P= 0.02) and 48 hours (29.7 ± 22.5 mm3; P= 0.035) after embolization. There was a good correlation between angiographic devascularization rate and the embolized tumor volume at 6 hours (r= 0.7; P= 0.03) and 48 hours (r= 0.78; P= 0.041). Preoperative meningioma embolization with calibrated microspheres is safe and effectively induces a significant and sustainable tissue transformation over 48 hours.

The Use of Noncontrast Quantitative MRI to Detect Gadolinium-Enhancing Multiple Sclerosis Brain Lesions: A Systematic Review and Meta-Analysis.

Concerns have arisen about the long-term health effects of repeat gadolinium injections in patients with multiple sclerosis and the incomplete characterization of MS lesion pathophysiology that results from relying on enhancement characteristics alone. Our aim was to perform a systematic review and meta-analysis analyzing whether noncontrast MR imaging biomarkers can distinguish enhancing and nonenhancing brain MS lesions. Our sources were Ovid MEDLINE, Ovid Embase, and the Cochrane data base from inception to August 2016. We included 37 journal articles on 985 patients with MS who had MR imaging in which T1-weighted postcontrast sequences were compared with noncontrast sequences obtained during the same MR imaging examination by using ROI analysis of individual MS lesions. We performed random-effects meta-analyses comparing the standard mean difference of each MR imaging metric taken from enhancing-versus-nonenhancing lesions. DTI-based fractional anisotropy values are significantly different between enhancing and nonenhancing lesions (P = .02), with enhancing lesions showing decreased fractional anisotropy compared with nonenhancing lesions. Of the other most frequently studied MR imaging biomarkers (mean diffusivity, magnetization transfer ratio, or ADC), none were significantly different (P values of 0.30, 0.47, and 0.19. respectively) between enhancing and nonenhancing lesions. Of the limited studies providing diagnostic accuracy measures, gradient-echo-based quantitative susceptibility mapping had the best performance in discriminating enhancing and nonenhancing MS lesions. MR imaging techniques and patient characteristics were variable across studies. Most studies did not provide diagnostic accuracy measures. All imaging metrics were not studied in all 37 studies. Noncontrast MR imaging techniques, such as DTI-based FA, can assess MS lesion acuity without gadolinium.

Reliability of noncontrast-enhancing tumor as a biomarker of IDH1 mutation status in glioblastoma

Isocitrate dehydrogenase 1 (IDH1) mutations in gliomas have been associated with a frontal lobe location and a greater proportion of noncontrast-enhancing tumour (nCET). The purpose of our study was to validate the utility of MRI imaging features in predicting IDH1 mutations in glioblastomas. Pre-operative MRIs of new glioblastoma patients, consisting of at least FLAIR and T1-weighted post-contrast sequences, were reviewed by a neuroradiologist based primarily on the VASARI feature set. IDH1 mutation testing was performed on all patients using immunohistochemistry. 153 patients met the inclusion criteria, of whom five had IDH1 mutations (3.3%). A frontal lobe location had equivalent frequency in both the IDH1-mutated and IDH1-wildtype cohorts (p=1.000). Three (60%) of the IDH1-mutated tumours had >33% nCET, compared to 21% of IDH1-wildtype (p=0.073). 12 tumours had a frontal lobe epicentre and >33% nCET, all being IDH1-wildtype. All five IDH1-mutated tumours had either a frontal lobe epicentre or >33% nCET, but none had both these features. Our results question the strength of the association between frontal lobe glioblastomas with substantial nCET and IDH1 mutations, as these features are also relatively frequent in IDH1-wildtype tumours, which are much more common. MRI is thus more useful for ruling out an IDH1 mutation rather than strongly suggesting its presence: if a particular glioblastoma does not have a frontal lobe epicentre and has less than 33% nCET, it can be predicted to be IDH1-wildtype with a high degree of confidence.

Abbreviated Screening Protocol for Breast MRI: A Feasibility Study

To compare the performance of two shortened breast magnetic resonance imaging (MRI) protocols to a standard MRI protocol for breast cancer screening. In this Health Insurance Portability and Accountability Act compliant, institutional review board-approved pilot study, three fellowship-trained breast imagers evaluated 48 breast MRIs (24 normal, 12 benign, and 12 malignant) selected from a high-risk screening population. MRIs were presented in three viewing protocols, and a final Breast Imaging-Reporting and Data System assessment was recorded for each case. The first shortened protocol (abbreviated 1) included only fat-saturated precontrast T2-weighted, precontrast T1-weighted, and first pass T1-weighted postcontrast sequences. The second shortened protocol (abbreviated 2) included the abbreviated 1 protocol plus the second pass T1-weighted postcontrast sequence. The third protocol (full), reviewed after a 1-month waiting period, included a nonfat-saturated T1-weighted sequence, fat-saturated T2-weighted, precontrast T1-weighted, and three or four dynamic postcontrast sequences. Interpretation times were recorded for the abbreviated 1 and full protocols. Sensitivity and specificity were compared via a chi-squared analysis. This pilot study was designed to detect a 10% difference in sensitivity with a power of 0.8. There was no significant difference in sensitivity between the abbreviated 1 (86%; P = .22) or abbreviated 2 (89%; P = .38) protocols and the full protocol (95%). There was no significant difference in specificity between the abbreviated 1 (52%; P = 1) or abbreviated 2 (45%; P = .34) protocols and the full protocol (52%). The abbreviated 1 and full protocol interpretation times were similar (2.98 vs. 3.56 minutes). In this pilot study, reader performance comparing two shortened breast MRI protocols to a standard protocol in a screening cohort were similar, suggesting that a shortened breast MRI protocol may be clinically useful, warranting further investigation.

Value of non-contrast sequences in magnetic resonance angiography of hepatic arterial vasculature

ObjectiveTo evaluate value of adding non-contrast MR angiographic sequence (In-Flow Inversion Recovery [IFIR]) to standard fat-suppressed T1-weighted postcontrast sequence (3D spoiled gradient echo [3D-GRE]) for evaluating hepatic arterial anatomy. MethodsRetrospective evaluation of 30 consecutive patients undergoing multiphase liver MRI. Individual vessels for IFIR/3D-GRE sequences were evaluated by two blinded readers using a four-point scale. Statistical analysis was performed using the Wilcoxon signed-rank test for vessel conspicuity between IFIR/3D-GRE sequences. ResultsIFIR alone diagnostically imaged 8.1% of vessels, 3D-GRE alone 25.8%, 55.8% by both 3D-GRE/IFIR, and 10.3% of vessels by neither. Two patients with variant vascular anatomy were visualized with both sequences. Addition of IFIR to 3D-GRE resulted in statistically significant increase in arterial visualization (p<0.001), 10% relative increase in identified vessels, and 3–5mi increase in acquisition time for total scan time of 30–35min. ConclusionsIFIR may be a useful adjunct to 3D-GRE in hepatic angiography without adding considerably to scan time. 10% more hepatic arteries were seen when combining information from IFIR/3D-GRE vs. 3D-GRE alone.

Quantifying Bone Marrow Edema in the Rheumatoid Cervical Spine Using Magnetic Resonance Imaging

To determine the reliability and feasibility of a new magnetic resonance imaging (MRI) score to quantify bone marrow edema (BME), synovitis, and erosions in the cervical spine of patients with rheumatoid arthritis (RA); and to investigate the correlations among neck pain, clinical markers of RA disease activity, and MRI features of disease activity in the cervical spine. Thirty patients with RA (50% with neck pain) and a Disease Activity Score 28-joint count > 3.2 had an MRI scan of their cervical spine. STIR, VIBE, and T1-weighted postcontrast sequences were used to quantify BME. MRI scans were scored for total BME, synovitis, and erosions using a new scoring method developed by the authors and assessed for reliability and feasibility. Associations between neck pain and clinical markers of disease activity were investigated. BME was present in 14/30 patients; 9/14 (64%) had atlantoaxial BME, 10/14 (71%) had subaxial BME, and 5/14 (36%) had both. Interobserver reliability for total cervical BME score was moderate [intraclass correlation coefficient (ICC) = 0.51]. ICC improved to 0.67 if only the vertebral bodies and dens were considered. There was no correlation between neck pain or clinical measures of RA disease activity and the presence of any MRI features including BME, synovitis, or erosions. Current RA disease activity scores do not identify activity in the cervical spine. An MRI score that quantifies BME, synovitis, and erosions in the cervical spine may provide useful information regarding inflammation and damage. This could alert clinicians to the presence of significant pathology and influence management.

Clinical Value of Dynamic MRI in the Diagnosis of Pituitary Microadenoma

MRI is today the first-choice technique for detection of pituitary microadenomas. The combination of T1-weighted spin-echo, T2-weighted spin-echo and T1-weighted spin-echo after intravenous gadolinium administration gives a clearly positive result in about 70% of cases. In the remaining 30% the hypersignal generated by the contrast agent can hide the smallest lesions. Dynamic MRI is considered capable of visualizing some of the smallest pituitary microadenomas not visible on conventional MRI, and has therefore become the most promising technique to image pituitary lesions. The purpose of this study is to compare the effectiveness of conventional and dynamic MRI. Fifty patients were examined with dynamic contrast-enhanced MRI of the pituitary gland. They were thought to have pituitary adenoma on the basis of clinical and biological data. MRI was performed at 1.5T (Siemens SP 63) with the acquisition of three sequences: 1) T2-weighted sequence 2) Dynamic study: (temporal resolution 17 s) 3) T1-weighted postcontrast sequence. In 10 cases (20%) no pathological findings were seen. In 32 cases (64%) pathological findings were seen both in dynamic and in SE T1 and T2-weighted images. In 8 cases (16%) pathological findings were observed only in the dynamic study. In 8 studies out of 50 (16%) dynamic MRI showed small (less than 7 mm) focal relatively hypointense areas in the pituitary gland, visible neither on SE T2-weighted pre-contrast nor on SE T1-weighted postcontrast images, leading to a diagnostic sensitivity from 64% to 80%. Dynamic MRI did not miss any lesions although in 3 cases the picture was more clear on SE sequences. We can conclude that dynamic MRI study of the pituitary gland improves accuracy in the diagnosis of pituitary microadenomas.