Establishing a 3-Tesla Magnetic Resonance Imaging Method for Assessing Diffuse Axonal Brain Injury in Rats

Traumatic brain injury (TBI) significantly contributes to death and disability worldwide. However, treatment options remain limited. Here, we focus on a specific pathology of TBI, diffuse axonal brain injury (DABI), which describes the process of the tearing of nerve fibers in the brain after blunt injury. Most protocols to study DABI do not incorporate a specific model for that type of pathology, limiting their ability to identify mechanisms and comorbidities of DABI. In this study, we developed a magnetic resonance imaging (MRI) protocol for DABI in a rat model using a 3-T clinical scanner. We compared the neuroimaging outcomes with histologic and neurologic assessments. In a sample size of 10 rats in the sham group and 10 rats in the DABI group, we established neurological severity scores before the intervention and at 48 h following DABI induction. After the neurological evaluation after DABI, all rats underwent MRI scans and were subsequently euthanized for histological evaluation. As expected, the neurological assessment showed a high sensitivity for DABI lesions indicated using the β-APP marker. Surprisingly, however, we found that the MRI method had greater sensitivity in assessing DABI lesions compared to histological methods. Out of the five MRI parameters with pathological changes in the DABI model, we found significant changes compared to sham rats in three parameters, and, as shown using comparative tests with other models, MRI was the most sensitive parameter, being even more sensitive than histology. We anticipate that this DABI protocol will have a significant impact on future TBI and DABI studies, advancing research on treatments specifically targeted towards improving patient quality of life and long-term outcomes.

Cerebrospinal fluid velocity changes of idiopathic scoliosis: a preliminary study on 3-T PC-MRI and 3D-SPACE-VFAM data

OBJECTIVES

To the best of our knowledge, there is no study on 3-Tesla (3-T) phase-contrast MRI (PC-MRI) and three-dimensional sampling perfection with application-optimized contrasts using different flip-angle evolutions (3D-SPACE-VFAM) in the evaluation of idiopathic scoliosis. This study aimed to investigate CSF abnormalities in the scoliotic spine using 3-T PC-MRI and 3D-SPACE-VFAM techniques.

METHODS

Thirty-four patients and 14 controls were examined with spinal PC-MRI and T2-weighted 3D-SPACE-VFAM techniques. Inter- and intra-reader agreements of flow-void phenomenon on 3D-SPACE-VFAM images, and velocity values on PC-MRI data were also evaluated.

RESULTS

There are statistically significant differences between scoliosis and control groups based on the highest and mean peak velocity values on PC-MRI images (p = 0.005 and p = 0.023, respectively). The main thoracic (MT) group's highest peak CSF velocity values were higher than the control group (p = 0.022). There is a significant difference between the patient and control groups regarding flow-void phenomenon scores on 3D-SPACE-VFAM images (p = 0.036). Inter- and intra-reader agreement values related to PC-MRI velocity measurements were perfect for all PC-MRI readings. Inter- and intra-reader agreement values of the flow-void phenomenon scores were moderate.

CONCLUSIONS

Our study has led us to conclude that idiopathic scoliosis is associated with CSF flow disturbances in parallel with the literature. MRI can demonstrate these abnormalities in a non-invasive and radiation-free way.

Non-contrast-enhanced 3-Tesla Magnetic Resonance Imaging Using Surface-coil and Sonography for Assessment of Hidradenitis Suppurativa Lesions

Hidradenitis suppurativa has a substantial negative effect on quality of life of affected persons. Diagnosis is based mainly on clinical examination. However, physical examination alone might underestimate disease severity compared with imaging modalities. We report here the application of non-contrast-enhanced 3-Tesla magnetic resonance imaging using surface-coil and sonography for assessment of hidradenitis suppurativa lesions based on topographic assessment of skin lesions. In addition, we review the literature regarding the application of ultrasound and magnetic resonance imaging in hidradenitis suppurativa.

Comparison of compressed sensing and conventional coronary magnetic resonance angiography for detection of coronary artery stenosis

PURPOSE

This study aimed to compare the efficacy of compressed sensing (CS) and conventional coronary magnetic resonance angiography (CMRA) in detecting coronary artery stenosis.

METHOD

Twenty-eight patients underwent 3 T contrast-enhanced CS and conventional CMRA; for late gadolinium enhancement (LGE) imaging, 0.1 mmol/kg gadolinium medium was infused. CS CMRA was scanned within the LGE waiting time. After the LGE image acquisition, conventional CMRA was performed. The diagnostic performance of both CMRA for the detection of significant stenosis was evaluated using coronary angiography as a reference. The analysis was conducted to examine the three main coronary artery vessels: left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA). These arteries were subdivided into 8 segments (LAD; main, proximal, and middle, LCX; proximal and distal, RCA; proximal, middle, and distal). Of these, hypoplastic segments and vessels after coronary stent implantation were excluded. The acquisition time of CS CMRA was compared with that of conventional CMRA.

RESULTS

The coronary arteries were evaluated in 197 segments. The sensitivity, specificity, and accuracy of CS CMRA in detecting significant stenosis were 85.2 %, 82.5 %, and 83.2 %, respectively, on a per-segment basis. Those of conventional CMRA were 85.2 %, 86.7 %, and 86.3 %, respectively. The acquisition time was 207 s (range, 144-258 s) for CS and 975 s (range, 787-1226s) for conventional CMRA (p < 0.001).

CONCLUSIONS

Similar to conventional CMRA, CS CMRA has shown potential for the detection of significant coronary artery stenosis.

Does 3-T fetal MRI induce adverse acoustic effects in the neonate? A preliminary study comparing postnatal auditory test performance of fetuses scanned at 1.5 and 3 T

BACKGROUND

Fetal MRI at 3 T is associated with increased acoustic noise relative to 1.5 T.

OBJECTIVE

The goal of this study is to determine if there is an increased prevalence of congenital hearing loss in neonates who had a 3-T prenatal MR vs. those who had it at 1.5 T.

MATERIALS AND METHODS

We retrospectively identified all subjects who had 3-T fetal MRI between 2012 and 2016 and also underwent universal neonatal hearing screening within 60 days of birth. Fetuses with incomplete hearing screening, magnetic resonance imaging (MRI) studies at both field strengths or fetuses affected by conditions associated with hearing loss were excluded. A random group of controls scanned at 1.5 T was identified. Five subjects had repeat same-strength MRIs (one at 3 T and four at 1.5 T). The pass/fail rate of the transient otoacoustic emissions test and auditory brainstem response test were compared using the Fisher exact test. A logistic regression was performed to assess the effects of other known risk factors for congenital hearing loss.

RESULTS

Three hundred forty fetal MRI examinations were performed at 3 T, of which 62 met inclusion criteria. A control population of 1.5-T fetal MRI patients was created using the same exclusion criteria, with 62 patients randomly selected from the eligible population. The fail rates of transient otoacoustic emissions test for the 1.5-T and 3-T groups were 9.7% and 6.5%, respectively, and for the auditory brainstem response test were 3.2% and 1.6%, respectively. There was no significant difference in the fail rate of either test between groups (P=0.74 for transient otoacoustic emissions test, and P=0.8 for auditory brainstem response test). The median gestational age of the 3-T group was 30 weeks, 1 day, significantly higher (P<0.001) than the 1.5-T group (median gestational age: 20 weeks, 2 days).

CONCLUSION

Our findings suggest that the increase in noise associated with 3 T does not increase the rate of clinically detectable hearing abnormalities.

3-tesla MRA: a systematic review and meta-analysis

BACKGROUND

Various protocols exist for magnetic resonance arthrogram (MRA) of the shoulder, including 3D isotropic scanning and positioning in neutral (2D neutral MRA), or abduction-external-rotation (ABER).

HYPOTHESIS

MRA does not improve diagnostic accuracy for labral tears when compared to magnetic resonance imaging (MRI) performed using 3-Tesla (3T) magnets.

METHOD

Systematic review of the Cochrane, MEDLINE, and PubMed databases according to PRISMA guidelines. Included studies compared 3T MRI or 3T MRA (index tests) to arthroscopic findings (reference test). Methodological appraisal performed using QUADAS-2. Pooled sensitivity and specificity were calculated.

RESULTS

Ten studies including 929 patients were included. Index test bias and applicability were a concern in the majority of studies. The use of arthroscopy as the reference test raised concern of verification bias in all studies. For anterior labral lesions, 3T MRI was less sensitive (0.83 vs. 0.87 p = 0.083) than 3T 2D neutral MRA. Compared to 3T 2D neutral MRA, both 3T 3D Isotropic MRA and 3T ABER MRA significantly improved sensitivity (0.87 vs. 0.95 vs. 0.94). For SLAP lesions, 3T 2D neutral MRA was of similar sensitivity to 3T MRI (0.84 vs. 0.83, p = 0.575), but less specific (0.99 vs. 0.92 p < 0.0001). For posterior labral lesions, 3T 2D neutral MRA had greater sensitivity than 3T 3D Isotropic MRA and 3T MRI (0.90 vs. 0.83 vs. 0.83).

CONCLUSIONS

At 3-T, MRA improved sensitivity for diagnosis of anterior and posterior labral lesions, but reduced specificity in diagnosis of SLAP tears. 3T MRA with ABER positioning further improved sensitivity in diagnosis of anterior labral tears.

LEVEL OF EVIDENCE

IV.

Post-mortem whole-body magnetic resonance imaging of human fetuses: a comparison of 3-T vs. 1.5-T MR imaging with classical autopsy

OBJECTIVE

To prospectively compare diagnostic accuracy of fetal post-mortem whole-body MRI at 3-T vs. 1.5-T.

METHODS

Between 2012 and 2015, post-mortem MRI at 1.5-T and 3-T was performed in fetuses after miscarriage/stillbirth or termination. Clinical MRI diagnoses were assessed using a confidence diagnostic score and compared with classical autopsy to derive a diagnostic error score. The relation of diagnostic error for each organ group with gestational age was calculated and 1.5-T with 3-T was compared with accuracy analysis.

RESULTS

135 fetuses at 12-41 weeks underwent post-mortem MRI (followed by conventional autopsy in 92 fetuses). For all organ groups except the brain, and for both modalities, the diagnostic error decreased with gestation (P < 0.0001). 3-T MRI diagnostic error was significantly lower than that of 1.5-T for all anatomic structures and organ groups, except the orbits and brain. This difference was maintained for fetuses <20 weeks gestation. Moreover, 3-T was associated with fewer non-diagnostic scans and greater concordance with classical autopsy than 1.5-T MRI, especially for the thorax, heart and abdomen in fetuses <20 weeks.

CONCLUSION

Post-mortem fetal 3-T MRI improves confidence scores and overall accuracy compared with 1.5-T, mainly for the thorax, heart and abdomen of fetuses <20 weeks of gestation.

KEY POINTS

• In PM-MRI, diagnostic error using 3-T is lower than that with 1.5-T. • In PM-MRI, diagnostic scan rate is higher using 3-T than 1.5-T. • In PM-MRI, concordance with classical autopsy increases with 3-T. • PM-MRI using 3-T is particularly interesting for thoracic and abdominal organs. • PM-MRI using 3-T is particularly interesting for fetuses < 20 weeks' gestation.

MRI of the anterior talofibular ligament, talar cartilage and os subfibulare: Comparison of isotropic resolution 3D and conventional 2D T2-weighted fast spin-echo sequences at 3.0 T

PURPOSE

To determine the accuracy of a three-dimensional (3D) T2-weighted fast spin-echo (FSE) magnetic resonance (MR) sequence compared with two-dimensional (2D) sequence for diagnosing anterior talofibular ligament (ATFL) tears, chondral lesion of the talus (CLT) and os subfibulare/avulsion fracture of the distal fibula (OSF).

MATERIALS AND METHODS

Thirty-five patients were included, who had undergone ankle MRI with 3D T2-weighted FSE and 2D T2-weighted FSE sequences, as well as subsequent ankle arthroscopy, between November 2013 and July 2014. Each MR imaging sequence was independently scored by two readers retrospectively for the presence of ATFL tears, CLT and OSF. The area under the receiver operating curve (AUC) was compared to determine the discriminatory power of the two image sequences. Interobserver agreement was expressed as unweighted kappa value.

RESULTS

Arthroscopic findings confirmed 21 complete tears of the ATFL, 14 partial tears of the ATFL, 17 CLTs and 7 OSFs. There were no significant differences in the diagnoses of ATFL tears (p = 0.074-0.501), CLT (p = 0.090-0.450) and OSF (p = 0.317) obtained from the 2D and 3D sequences by either reader. The interobserver agreement rates between two readers using the 3D T2-weighted FSE sequence versus those obtained with the 2D sequence were substantial (κ = 0.659) versus moderate (κ = 0.553) for ATFL tears, moderate (κ = 0.499) versus substantial (κ = 0.676) for CLT and substantial (κ = 0.621) versus substantial (κ = 0.689) for OSF.

CONCLUSION

Three-dimensional isotropic T2-weighted FSE MRI of the ankle resulted in no statistically significant difference in diagnostic performance compared to two-dimensional T2-weighted FSE MRI in the evaluation of ATFL tears, CLTs and OSFs.

Diagnosis of rotator cuff tears using 3-Tesla MRI versus 3-Tesla MRA: a systematic review and meta-analysis

OBJECTIVE

To compare the diagnostic accuracy of magnetic resonance imaging (MRI), 2-dimensional magnetic resonance arthrogram (MRA) and 3-dimensional isotropic MRA in the diagnosis of rotator cuff tears when performed exclusively at 3-T.

MATERIALS AND METHODS

A systematic review was undertaken of the Cochrane, MEDLINE and PubMed databases in accordance with the PRISMA guidelines. Studies comparing 3-T MRI or 3-T MRA (index tests) to arthroscopic surgical findings (reference test) were included. Methodological appraisal was performed using QUADAS 2. Pooled sensitivity and specificity were calculated and summary receiver-operating curves generated. Kappa coefficients quantified inter-observer reliability.

RESULTS

Fourteen studies comprising 1332 patients were identified for inclusion. Twelve studies were retrospective and there were concerns regarding index test bias and applicability in nine and six studies respectively. Reference test bias was a concern in all studies. Both 3-T MRI and 3-T MRA showed similar excellent diagnostic accuracy for full-thickness supraspinatus tears. Concerning partial-thickness supraspinatus tears, 3-T 2D MRA was significantly more sensitive (86.6 vs. 80.5 %, p = 0.014) but significantly less specific (95.2 vs. 100 %, p < 0.001). There was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA showed similar accuracy to 3-T conventional 2D MRA.

CONCLUSION

Three-Tesla MRI appeared equivalent to 3-T MRA in the diagnosis of full- and partial-thickness tears, although there was a trend towards greater accuracy in the diagnosis of subscapularis tears with 3-T MRA. Three-Tesla 3D isotropic MRA appears equivalent to 3-T 2D MRA for all types of tears.

3T magnetic resonance imaging testing of externally programmable shunt valves

Background:

Exposure of externally programmable shunt-valves (EPS-valves) to magnetic resonance imaging (MRI) may lead to unexpected changes in shunt settings, or affect the ability to reprogram the valve. We undertook this study to examine the effect of exposure to a 3T MRI on a group of widely used EPS-valves.

Methods:

Evaluations were performed on first generation EPS-valves (those without a locking mechanism to prevent changes in shunt settings by external magnets other than the programmer) and second generation EPS-valves (those with a locking mechanisms). Fifteen new shunt-valves were divided into five groups of three identical valves each, and then exposed to a series of six simulated MRI scans. After each of the exposures, the valves were evaluated to determine if the valve settings had changed, and whether the valves could be reprogrammed. The study produced 18 evaluations for each line of shunt-valves.

Results:

Exposure of the first generation EPS-valves to a 3T magnetic field resulted in frequent changes in the valve settings; however, all valves retained their ability to be reprogrammed. Repeated exposure of the second generation EPS-valves has no effect on shunt valve settings, and all valves retained their ability to be interrogated and reprogrammed.

Conclusions:

Second generation EPS-valves with locking mechanisms can be safely exposed to repeated 3T MRI systems, without evidence that shunt settings will change. The exposure of the first generation EPS-valves to 3T MRI results in frequent changes in shunt settings that necessitate re-evaluation soon after MRI to avoid complications.