T2-weighted Magnetic Resonance Imaging Sequences Research Articles

More negative sagittal tibial tuberosity-trochlear groove distances are correlated with larger patellofemoral chondral lesion size.

The purpose of this study is to assess the association between sagittal tibial tuberosity-trochlear groove (sTT-TG) distance and patellofemoral chondral lesion size in patients undergoing cartilage restoration procedures. A retrospective cohort analysis of patients who underwent an osteochondral allograft transplantation or matrix-induced autologous chondrocyte implantation in the patellofemoral compartment, from 2010 to 2020, were included if they had patellofemoral high-grade lesions, magnetic resonance imaging (MRI) and minimum 2-year follow-up. The preoperative sTT-TG distance was measured independently on axial T2-weighted MRI sequences by two authors, each at least two weeks apart. Intraoperative lesion size was reported according to operative report measurements by the attending surgeon. An interclass correlation coefficient (ICC) was calculated to assess intra- and inter-rater reliability, and categorical data analysis and linear regression models were used to assess the relationship between sTT-TG and lesion size. A total of 80 patients (50 females) with a mean age of 31.5 ± 10.4 years, body mass index of 27.0 ± 5.9 kg/m2 and follow-up of 61.5 ± 21.4 months were included. A total of 107 lesions were present: 63 patients with unipolar (patella = 41, trochlea = 22) and 22 with bipolar lesions. The mean MRI defect size was 1.6 ± 1.0 cm2 and the mean intraoperative defect size was 3.8 ± 2.4cm2. Intra- (ICC: 0.99,0.98) and inter-rater reliability (ICC: 0.96) were excellent for both MRI defect size and sTT-TG measurements. The mean sTT-TG was -4.8 ± 4.9 mm and was significantly inversely related to MRI defect size (-0.45, p < 0.01), intraoperative patellar lesion size (-0.32, p = 0.01), total lesion area (-0.22, p = 0.04), but not trochlear lesion size (-0.09, p = 0.56). Multivariable regression demonstrated a more negative sTT-TG remained an independent variable correlated with larger MRI-measured patellofemoral defect sizes and intraoperative patellar lesions. A more negative sTT-TG was an independent variable correlated with larger patellofemoral lesions in patients undergoing patellofemoral cartilage restoration. Level III, Diagnostic.

MRI T1-Weighted Fat Segmentation Based on Active Contour for Osteosarcoma Patients

Osteosarcoma (OS) is the most common and frequent primary bone cancer in children and adolescents. This type of bone cancer often developed at the long bones’ extremities close to the metaphyseal growth plates. To address these issues, OS quantitative analysis is performed using Magnetic Resonance Imaging (MRI) to plan surgical procedures and track the effectiveness of treatment. Fat suppression is commonly employed to eliminate the fat signal from T1-Weighted MRI sequence. The suppressed fat signal in T1-Weighted is important and often used to identify abnormalities in other MRI sequences. In clinical, MRI images must be interpreted by a radiologist. Manually outlining the tumour location is laborious and subjective. Image processing involves segmentation to separate information from the desired target region of the image. Active Contour (AC) is an algorithm often used in medical images for segmentation. Nevertheless, the process of mask initialization can be challenging and requires careful attention. This study proposes a method to define the mask initialization so that the AC has a starting point to extract fat in T1-Weighted for the purpose of fat suppression. From the results obtained, AC with the proposed mask initialization method successfully segmented the fat in T1-Weighted MRI images with accuracy, precision, recall and F1-score of 0.92, 0.86, 0.88 and 0.89 respectively.

Advantages of cone beam computed tomography for evaluation of subchondral insufficiency fractures of the knee compared to MRI

To determine the diagnostic yield of cone beam computed tomography (CBCT) compared with 3 T magnetic resonance imaging (MRI) for the evaluation of subchondral insufficiency fractures of the knee. Consecutive patients with subchondral insufficiency fractures of the knee examined by 3 T MRI and CBCT of the femoral condyles were reviewed. Two experienced raters graded the lesion severity on 3 T MRI and CBCT images: grade 1: no signs of a subchondral bone lesion; grade 2: subchondral trabecular fracture or cystic changes, but without infraction of the subchondral bone plate; grade 3: collapse of the subchondral bone plate. Ratings were repeated after six weeks to determine reliability. In addition, the bone lesion size was measured as elliptical area (mm2) and compared between CBCT and T1-weighted MRI sequences. Among 30 patients included (43.3% women; mean age: 60.9 ± 12.8 years; body mass index (BMI) 29.0 ± 12.8 kg/m2), the medial femoral condyle was affected in 21/30 patients (70%). The grading of subchondral lesions between MRI and CBCT did not match in 12 cases (40%). Based on MRI images, an underestimation (i.e., undergrading) compared with CBCT was observed in nine cases (30%), whereas overgrading occurred in three cases (10%). Compared to CBCT, routine T1-weighted 3 T sequences significantly overestimated osseus defect zones in sagittal (84.7 ± 68.9 mm2 vs. 35.9 ± 38.2 mm2, p < 0.01, Cohen’s d = 1.14) and coronal orientation (53.1 ± 24.0 mm2 vs. 22.0 ± 15.2 mm2, p < 0.01, Cohen’s d = 1.23). The reproducibility of the grading determined by intra- and inter-rater agreement was very high in MRI (intra-class correlation coefficient (ICC) 0.78 and 0.90, respectively) and CBCT (ICC 0.96 and 0.96, respectively). In patients with subchondral insufficiency fractures of the knee, the use of CBCT revealed discrepancies in lesion grading compared with MRI. These findings are clinically relevant, as precise determination of subchondral bone plate integrity may influence the decision about conservative or surgical treatment. CBCT represents our imaging modality of choice for grading the lesion and assessing subchondral bone plate integrity. MRI remains the gold standard modality to detect especially early stages.

Poster 267: Relationship Between Sagittal Tibial Tubercle-Trochlear Groove Distance and Outcomes Following Cartilage Restoration for Patellofemoral Articular Cartilage Lesions

Objectives: Increased contact force in the patellofemoral (PF) joint is a known contributor to cartilage damage and pain. A tibial tubercle that is posterior to the trochlear groove may lead to aberrant loading and cartilage wear. The sagittal tibial-tubercle trochlear groove distance (sTT-TG), defined as the distance between the nadir of the trochlear groove and the most anterior aspect of the tibial tubercle, aids in quantifying the degree of risk of acquiring new lesions. However, the relationship between sTT-TG and patient-reported outcomes following surgery has not been assessed. Therefore, the purpose of this study is to assess the association between sTT-TG and post-operative outcomes in patients undergoing cartilage restoration procedures for PF articular cartilage lesions. Methods: A retrospective review of patients who underwent osteochondral allograft (OCA) transplantation or autologous chondrocyte implantation (ACI) at a single academic institution from 2010 to 2020 was conducted. Patients were included they underwent OCA or ACI for a high-grade (Outerbridge 3 or 4) articular cartilage lesion located in the patellofemoral joint (unipolar or bipolar), if they were between 18 and 50 years of age at the time of surgery, had magnetic resonance imaging (MRI) available, and had a minimum 2-year clinical follow-up. Demographic data such as age, sex, body mass index (BMI), as well as defect characteristics including size, number, and grade were collected. Before surgery, sTT-TG distance was measured independently on axial T2-weighted MRI sequences by two raters (Rater A and Rater B). Both raters measured the sTT-TG for the entire cohort at two different time points with a two-week time interval between each rater’s initial and follow-up measurements. The Interclass Coefficient (ICC) using a single measure, absolute agreement, two-way mixed effects model was used to test the intra-rater reliability of Rater A and Rater B; mean measures were used to assess the inter-rater reliability for the combined mean of the two rater’s measurements. Patients were surveyed to assess pain and satisfaction on a Visual Analog Scale (VAS) from 0 to 100. Functional outcomes were collected using the Knee Injury and Osteoarthritis Outcome Score (KOOS). The rate of return to sports, complications, and graft failure were also recorded [JT1]. An independent samples t-test was used to compare lesion size between the OCA and ACI group. Linear and logistic regression models accounting for age, sex, BMI, and sTT-TG distance were used to assess the relationship between sTT-TG and PROs. Results: A total of 76 patients, mostly female (61.8%), with a mean age of 31.9 ± 8.3 years, BMI of 26.8, and 60.6 ± 23.6-month follow-up were included. There were 37 (48.7%) patients that underwent OCA transplantation and 39 (51.3%) that underwent ACI. A total of 98 lesions were identified, with the majority (n = 93, 94.9%) being Grade 4. Overall, 54 patients had unipolar lesions and 22 had bipolar lesions. The mean defect size was 2.9 ± 1.4 cm2 and 3.5 ± 2.9 cm2 for the OCA and ACI groups (p = 0.459), respectively, with an overall mean lesion area of 3.2 ± 2.3 cm2. Intra-rater reliability for sTT-TG measurements at each time point was excellent for Rater A (ICC of 0.99 [0.986-0.994] p&lt;0.001) and Rater B (ICC of 0.99 [0.985-0.994]). Inter-rater reliability was excellent (ICC of 0.97 [0.955-.982] p&lt;0.001), with an overall mean sTT-TG of -4.98 ± 4.93 mm (range: -18.9, 5.7). On average, 48.7% (n = 37) of patients returned to sport and of those, 22.4% (n=17) returned to a similar or higher level of sport activity. Mean pain and satisfaction were 26.7 ± 25.1 and 73.8 ± 27.7, respectively. Collectively, the mean KOOS subscores were - KOOS symptoms: 71.4 ± 2.3, KOOS pain: 79.5 ± 2.0, KOOS sport: 60.2 ± 2.8, and KOOS QoL: 52.0 ± 2.6. When controlling for age, sex, BMI, and follow-up, sTT-TG was not predictive of RTS (p=0.706), pain (p=0.698), satisfaction (0.757), or any KOOS subscore (p&gt;0.05). Although, older age was associated with worse satisfaction (-0.819, 95% CI [-1.608,-0.03] and inferior KOOS pain (-0.606, 95% CI [-1.096,-0.116]), KOOS sport (-0.739, 95% CI [-1.445,-0.032]), and KOOS QoL (-0.786, 95% CI [-1.455,-0.117] p&lt;0.05). Conclusions: In this cohort of patients that underwent an OCA or ACI for PF cartilage lesions, sTT-TG was not predictive of post-operative patient reported functional outcomes or complications. These findings suggest that while a more posterior tibial tubercle (negative sTT-TG) may contribute to a higher incidence of cartilage pathology, patients can have favorable short-term outcomes following cartilage restoration with OCA or ACI.

Optimising needle depth in temporomandibular joint arthrocentesis: a magnetic resonance-based study for safety and efficacy

The aim of this paper was to determine the optimal needle depth for temporomandibular joint (TMJ) arthrocentesis using magnetic resonance imaging (MRI), with the aim of improving procedural safety and efficacy in clinical practice. A retrospective analysis of 264 TMJ MRIs from 132 patients at Istanbul Medipol Mega University Hospital was conducted. T2-weighted MRI sequences were utilised to measure distances from skin to joint capsules at varying needle entry points, applying the double puncture technique. The study adhered to ethical standards with appropriate approvals. The analysis revealed significant gender-related variations in needle depths (females showing shorter distances than males, p < 0.05). No significant gender differences were found in condylar angles. An inverse correlation between age and condylar angle suggested age-related anatomical changes. Crucially, a 20 mm needle depth was identified as safer and more effective than the previously recommended 25 mm. This study underscores the necessity of revising needle depth to 20 mm in TMJ arthrocentesis. These findings hold significant implications for improving procedural safety and catering to demographic variations.

A Novel Positive-Contrast Magnetic Resonance Imaging Line Marker for High-Dose-Rate (HDR) MRI-Assisted Radiosurgery (MARS).

Magnetic resonance imaging (MRI) can facilitate accurate organ delineation and optimal dose distributions in high-dose-rate (HDR) MRI-Assisted Radiosurgery (MARS). Its use for this purpose has been limited by the lack of positive-contrast MRI markers that can clearly delineate the lumen of the HDR applicator and precisely show the path of the HDR source on T1- and T2-weighted MRI sequences. We investigated a novel MRI positive-contrast HDR brachytherapy or interventional radiotherapy line marker, C4:S, consisting of C4 (visible on T1-weighted images) complexed with saline. Longitudinal relaxation time (T1) and transverse relaxation time (T2) for C4:S were measured on a 1.5 T MRI scanner. High-density polyethylene (HDPE) tubing filled with C4:S as an HDR brachytherapy line marker was tested for visibility on T1- and T2-weighted MRI sequences in a tissue-equivalent female ultrasound training pelvis phantom. Relaxivity measurements indicated that C4:S solution had good T1-weighted contrast (relative to oil [fat] signal intensity) and good T2-weighted contrast (relative to water signal intensity) at both room temperature (relaxivity ratio > 1; r2/r1 = 1.43) and body temperature (relaxivity ratio > 1; r2/r1 = 1.38). These measurements were verified by the positive visualization of the C4:S (C4/saline 50:50) HDPE tube HDR brachytherapy line marker on both T1- and T2-weighted MRI sequences. Orientation did not affect the relaxivity of the C4:S contrast solution. C4:S encapsulated in HDPE tubing can be visualized as a positive line marker on both T1- and T2-weighted MRI sequences. MRI-guided HDR planning may be possible with these novel line markers for HDR MARS for several types of cancer.

Differentiation of hemispheric white matter lesions in migraine and multiple sclerosis with similar radiological features using advanced MRI.

White matter hyperintensities (WMHs), presented on T2-weighted or fluid-attenuated inversion recovery magnetic resonance imaging (MRI) sequences, are lesions in the human brain that can be observed in both migraine and multiple sclerosis (MS). Seventeen migraine patients and 15 patients with relapsing-remitting multiple sclerosis with WMHs, and 17 healthy subjects age-and sex-matched to the migraine group were prospectively enrolled and underwent conventional and advanced MRI studies with diffusion-and perfusion-weighted imaging and single voxel proton magnetic resonance spectroscopy. In both disease groups, elevated T2 relaxation time, apparent diffusion coefficient (ADC) values, and decreased N-acetyl-aspartate levels were found in the intralesional white matter compared to the contralateral normal-appearing white matter (NAWM), while there was no difference between the hemispheres of the control subjects. Migraine patients had the lowest intralesional creatine + phosphocreatine and myo-inositol (mI) values among the three groups, while patients with MS showed the highest intralesional T1 and T2 relaxation times, ADC, and mI values. In the contralateral NAWM, the same trend with mI changes was observed in migraineurs and MS patients. No differences in perfusion variables were observed in any groups. Our multimodal study showed that tissue damage is detectable in both diseases. Despite the differences in various advanced MRI measures, with more severe injury detected in MS lesions, we could not clearly differentiate the two white matter lesion types.

CT-like images based on T1-weighted gradient echo MRI sequences for the assessment of fractures of the hand and wrist compared to CT.

To evaluate the performance of a 3D T1-weighted gradient-echo (3D T1GRE) computed tomography (CT)-like magnetic resonance imaging (MRI) sequence for detecting and assessing wrist and hand fractures compared to conventional CT. Subjects with acute wrist or hand fracture in CT underwent additional 3T MRI including a CT-like 3D T1GRE sequence and were compared to patients without fractures. Two radiologists assessed fracture morphology on both modalities according to the Arbeitsgemeinschaft Osteosynthese (AO) and graded image quality and diagnostic confidence on a 5-point Likert scale. Besides diagnostic test evaluation, differences in image quality and diagnostic confidence between CT-like MRI and CT were calculated using the Wilcoxon test. Agreement of AO classification between modalities and readers was assessed using Cohen's Kappa. Twenty-eight patients with 43 fractures and 43 controls were included. Image quality (3D T1GRE 1.19 ± 0.37 vs. CT 1.22 ± 0.42; p = 0.65) and diagnostic confidence (3D T1GRE 1.28 ± 0.53 vs. CT 1.28 ± 0.55; p = 1.00) were rated excellent for both modalities. Regarding the AO classification, intra- (rater 1 and rater 2, κ = 0.89; 95% CI 0.80-0.97) and interrater agreement were excellent (3D T1GRE, κ = 0.82; 95% CI, 0.70-0.93; CT, κ = 0.85; 95% CI, 0.75-0.94). CT-like MRI showed excellent sensitivity, specificity and accuracy for fracture detection (reader 1: 1.00, 0.92, 0.96; reader 2: 0.98, 0.94, 0.96). CT-like MRI is a comparable alternative to CT for assessing hand and wrist fractures, offering the advantage of avoiding radiation exposure.

Improving portable low-field MRI image quality through image-to-image translation using paired low- and high-field images

Low-field portable magnetic resonance imaging (MRI) scanners are more accessible, cost-effective, sustainable with lower carbon emissions than superconducting high-field MRI scanners. However, the images produced have relatively poor image quality, lower signal-to-noise ratio, and limited spatial resolution. This study develops and investigates an image-to-image translation deep learning model, LoHiResGAN, to enhance the quality of low-field (64mT) MRI scans and generate synthetic high-field (3T) MRI scans. We employed a paired dataset comprising T1- and T2-weighted MRI sequences from the 64mT and 3T and compared the performance of the LoHiResGAN model with other state-of-the-art models, including GANs, CycleGAN, U-Net, and cGAN. Our proposed method demonstrates superior performance in terms of image quality metrics, such as normalized root-mean-squared error, structural similarity index measure, peak signal-to-noise ratio, and perception-based image quality evaluator. Additionally, we evaluated the accuracy of brain morphometry measurements for 33 brain regions across the original 3T, 64mT, and synthetic 3T images. The results indicate that the synthetic 3T images created using our proposed LoHiResGAN model significantly improve the image quality of low-field MRI data compared to other methods (GANs, CycleGAN, U-Net, cGAN) and provide more consistent brain morphometry measurements across various brain regions in reference to 3T. Synthetic images generated by our method demonstrated high quality both quantitatively and qualitatively. However, additional research, involving diverse datasets and clinical validation, is necessary to fully understand its applicability for clinical diagnostics, especially in settings where high-field MRI scanners are less accessible.

Examining the Role of Paraspinal Musculature in Postoperative Disability After Lumbar Fusion Surgery for Degenerative Spondylolisthesis.

Retrospective analysis of prospectively enrolled patients. To evaluate the relationship between paraspinal muscle (PM) atrophy and Oswestry Disability Index (ODI) improvement after spinal fusion surgery for degenerative lumbar spondylolisthesis. Atrophy of the PM is linked to multiple spinal conditions, sagittal malalignment, and increased postoperative complications. However, only limited evidence for the effect on patient-reported outcomes exists. Patients with degenerative lumbar spondylolisthesis undergoing decompression and fusion surgery were analyzed. Patients with missing follow-up, no imaging, or inadequate image quality were excluded. The ODI was assessed preoperatively and two years postoperatively. A cross-sectional area of the PM was measured on a T2-weighted magnetic resonance imaging sequence at the upper endplate of L4. On the basis of the literature, a 10-point improvement cutoff was defined as the minimum clinically important difference. Patients with a baseline ODI below the minimum clinically important difference were excluded. Logistic regression was used to calculate the association between fatty infiltration (FI) of the PM and improvement in ODI, adjusted for age, sex, and body mass index. A total of 133 patients were included in the final analysis, with only two lost to follow-up. The median age was 68 years (IQR 62-73). The median preoperative ODI was 23 (IQR 17-28), and 76.7% of patients showed improvement in their ODI score by at least 10 points. In the multivariable regression, FI of the erector spinae and multifidus increased the risk of not achieving clinically relevant ODI improvement ( P =0.01 and <0.001, respectively). No significant association was found for the psoas muscle ( P =0.158). This study demonstrates that FI of the erector spinae and multifidus is significantly associated with less likelihood of clinically relevant ODI improvement after decompression and fusion. Further research is needed to assess the effect of interventions.

Intracranial Arachnoiditis and Hydrocephalus

A 62-year-old man presented a diffuse and predominantly cisternal acute nonaneurysmal subarachnoid hemorrhage associated with hydrocephalus. An external ventricular drain was placed, followed by clinical deterioration after its removal. At this point, a heavily T2-weighted high-resolution sequence of a brain magnetic resonance imaging showed acute hydrocephalus recrudescence and multiple arachnoid adhesions in the supravermian and interpeduncular cisterns, creating a loculated/cystic appearance. The diagnosis of intracranial arachnoiditis was made. Intracranial arachnoiditis results from meningeal inflammation. Fibrosis and adhesions at the subarachnoid spaces may follow, restricting cerebrospinal fluid circulation, particularly at the cranial base. Hydrocephalus probably resulted from the combination of subarachnoid hemorrhage and extensive scaring at the basal cisterns, precluding transdural and transvenous cerebrospinal fluid efflux. Heavily T2-weighted high-resolution magnetic resonance imaging sequences allow an exquisite depiction of arachnoiditis, displaying obstructive cisternal membranes, and contribute to better etiologic assessment and management of hydrocephalus.

Imaging evaluation of a proposed 3D generative model for MRI to CT translation in the lumbar spine

BACKGROUND CONTEXTA computed tomography (CT) and magnetic resonance imaging (MRI) are used routinely in the radiologic evaluation and surgical planning of patients with lumbar spine pathology, with the modalities being complimentary. We have developed a deep learning algorithm which can produce 3D lumbar spine CT images from MRI data alone. This has the potential to reduce radiation to the patient as well as burden on the health care system. PURPOSEThe purpose of this study is to evaluate the accuracy of the synthetic lumbar spine CT images produced using our deep learning model. STUDY DESIGNA training set of 400 unpaired CTs and 400 unpaired MRI scans of the lumbar spine was used to train a supervised 3D cycle-Gan model. Evaluators performed a set of clinically relevant measurements on 20 matched synthetic CTs and true CTs. These measurements were then compared to assess the accuracy of the synthetic CTs. PATIENT SAMPLEThe evaluation data set consisted of 20 patients who had CT and MRI scans performed within a 30-day period of each other. All patient data was deidentified. Notable exclusions included artefact from patient motion, metallic implants or any intervention performed in the 30 day intervening period. OUTCOME MEASURESThe outcome measured was the mean difference in measurements performed by the group of evaluators between real CT and synthetic CTs in terms of absolute and relative error. METHODSData from the 20 MRI scans was supplied to our deep learning model which produced 20 “synthetic CT” scans. This formed the evaluation data set. Four clinical evaluators consisting of neurosurgeons and radiologists performed a set of 24 clinically relevant measurements on matched synthetic CT and true CTs in 20 patients. A test set of measurements were performed prior to commencing data collection to identify any significant interobserver variation in measurement technique. RESULTSThe measurements performed in the sagittal plane were all within 10% relative error with the majority within 5% relative error. The pedicle measurements performed in the axial plane were considerably less accurate with a relative error of up to 34%. CONCLUSIONSThe computer generated synthetic CTs demonstrated a high level of accuracy for the measurements performed in-plane to the original MRIs used for synthesis. The measurements performed on the axial reconstructed images were less accurate, attributable to the images being synthesized from nonvolumetric routine sagittal T1-weighted MRI sequences. It is hypothesized that if axial sequences or volumetric data were input into the algorithm these measurements would have improved accuracy.

Automated Radiomic Analysis of Vestibular Schwannomas and Inner Ears Using Contrast-Enhanced T1-Weighted and T2-Weighted Magnetic Resonance Imaging Sequences and Artificial Intelligence.

To objectively evaluate vestibular schwannomas (VSs) and their spatial relationships with the ipsilateral inner ear (IE) in magnetic resonance imaging (MRI) using deep learning. Cross-sectional study. A total of 490 adults with VS, high-resolution MRI scans, and no previous neurotologic surgery. MRI studies of VS patients were split into training (390 patients) and test (100 patients) sets. A three-dimensional convolutional neural network model was trained to segment VS and IE structures using contrast-enhanced T1-weighted and T2-weighted sequences, respectively. Manual segmentations were used as ground truths. Model performance was evaluated on the test set and on an external set of 100 VS patients from a public data set (Vestibular-Schwannoma-SEG). Dice score, relative volume error, average symmetric surface distance, 95th-percentile Hausdorff distance, and centroid locations. Dice scores for VS and IE volume segmentations were 0.91 and 0.90, respectively. On the public data set, the model segmented VS tumors with a Dice score of 0.89 ± 0.06 (mean ± standard deviation), relative volume error of 9.8 ± 9.6%, average symmetric surface distance of 0.31 ± 0.22 mm, and 95th-percentile Hausdorff distance of 1.26 ± 0.76 mm. Predicted VS segmentations overlapped with ground truth segmentations in all test subjects. Mean errors of predicted VS volume, VS centroid location, and IE centroid location were 0.05 cm 3 , 0.52 mm, and 0.85 mm, respectively. A deep learning system can segment VS and IE structures in high-resolution MRI scans with excellent accuracy. This technology offers promise to improve the clinical workflow for assessing VS radiomics and enhance the management of VS patients.

3D zero-echo time and 3D T1-weighted gradient-echo MRI sequences as an alternative to CT for the evaluation of the lumbar facet joints and lumbosacral transitional vertebrae.

Computed tomography (CT) is the reference standard for assessment of the bone. Magnetic resonance imaging (MRI) developments enable a CT-like visualization of the osseous structures. To assess the diagnostic performance of 3D zero-echo time (3D-ZTE) and 3D T1-weighted gradient-echo (3D-T1GRE) MRI sequences for the evaluation of lumbar facet joints (LFJs) and the detection of lumbosacral transitional vertebrae (LSTV) using CT as the reference standard. In total, 87 adult patients were included in this prospective study. Evaluation of degenerative changes of the facet joints at the L3/L4, L4/L5, and L5/S1 levels on both sides was performed by two readers using a 4-point Likert scale. LSTV were classified according to Castelvi et al. Image quality was quantitatively measured using the signal-to-noise (SNR) and contrast-to-noise (CNR) ratios. Intra-reader, inter-reader, and inter-modality reliability were calculated using Cohen's kappa statistic. Intra-reader agreement for 3D-ZTE, 3D-T1GRE, and CT was 0.607, 0.751, and 0.856 and inter-reader agreement was 0.535, 0.563, and 0.599, respectively. The inter-modality agreement between 3D-ZTE and CT was 0.631 and between 3D-T1GRE and CT 0.665. A total of LSTV were identified in both MR sequences with overall comparable accuracy compared to CT. Mean SNR for bone, muscle, and fat was highest for 3D-T1GRE and mean CNR was highest for CT. 3D-ZTE and 3D-T1GRE MRI sequences can assess the LFJs and LSTV and may serve as potential alternatives to CT.

Spinal epidural tuberculoma with osseous involvement: illustrative case.

A tuberculosis infection of the central nervous system can present as a localized, intraspinal tuberculoma. These lesions may cause spinal cord compression requiring early identification and surgical decompression to limit deleterious neurological sequelae. A 28-year-old female with a history of opioid use disorder presented with low-back pain in the setting of trauma with progressive bilateral lower extremity radiculopathy and paraparesis. T1- and T2-weighted magnetic resonance imaging sequences of the spine demonstrated a heterogeneously hyperintense extra-axial epidural mass at T11 with mass effect. Biopsy of the lesion revealed benign soft tissue with necrosis and caseating granulomatous inflammation consistent with tuberculoma. The patient underwent laminectomy and debulking of mass for decompression and was subsequently began antitubercular treatment with good neurological outcome. To the best of the authors' knowledge, there are only a handful of microbiologically and radiographically confirmed cases of spinal epidural tuberculoma in English literature. These lesions are rare and difficult to clinically and radiographically characterize in the absence of systemic pulmonary TB symptoms. Tuberculoma is an important differential for a spinal epidural mass, particularly because resection with systemic antitubercular treatment results in symptom resolution.

Evaluation of optic nerve by histogram analysis on MRI in patients with isolated optic neuritis

Objectives: We aimed to evaluate the Magnetic Resonance Imaging (MRI) histogram texture analyzis of the optic nerve by comparing patients of isolated optic neuritis with a healthy control group and to provide objective information without using contrast in the diagnosis of the disease. Methods: A total of 40 patients, including 20 patients with isolated optic neuritis (13 females, 7 males) and 20 healthy controls (11 females, 9 males), were included in the study. Non-contrast brain MR images of the patient and control groups were analyzed retrospectively. In the coronal T2-weighted MRI sequence of both groups, the Region of Interest (ROI) was placed in the extraocular anterior 1/3 of the optic nerve of both eyes. Numerical data were obtained using histogram analysis and the data were evaluated in the MATLAB program. The data were compared statistically. In addition, sensitivity and specificity were determined by Receiver Operating Characteristic (ROC) curve analysis. Results: As a result of histogram analysis, a significant difference was found between the mean values in the healthy and affected eye of the patients with isolated optic neuritis and the mean values of the control group (p &amp;lt; 0.05). A significant difference was found in standard deviation, minimum, maximum, median, variance values between both groups. ROC analysis was performed for mean value, AUC = 0.943 and when threshold value was selected as 354.258 Haunsfield Unit, two groups could be differentiated with 84.2% of sensitivity and 92.1% of specificity. We can say that patients with isolated optic neuritis also have histological effects on the clinically asymptomatic eye. Conclusions: Histogram analysis can be used in the diagnosis of the patients with isolated optic neuritis without the need to use contrast in their MRI. In addition, histological effect can be detected in the eye that does not show clinical symptoms with histogram analysis.

Molecular Magnetic Resonance Imaging of Aneurysmal Inflammation Using a Redox Active Iron Complex.

Inflammation plays a key role in driving brain aneurysmal instability and rupture, but clinical tools to noninvasively differentiate between inflamed and stable aneurysms are lacking. We hypothesize that imaging oxidative changes in the aneurysmal microenvironment driven by myeloid inflammatory cells may represent a noninvasive biomarker to evaluate rupture risk. In this study, we performed initial evaluation of the oxidatively activated probe Fe-PyC3A as a tool for magnetic resonance imaging (MRI) of inflammation in a rabbit model of saccular aneurysm. The difference in longitudinal relaxivity ( r1 ) in reduced and oxidized states of Fe-PyC3A was measured in water and blood plasma phantoms at 3 T. A rabbit saccular aneurysm model was created by endovascular intervention/elastinolysis with subsequent decellularization in situ. Rabbits were imaged at 4 weeks (n = 4) or 12 weeks (n = 4) after aneurysmal induction, when luminal levels of inflammation reflected by the presence of myeloperoxidase positive cells are relatively high and low, respectively, using a 3 T clinical scanner. Both groups were imaged dynamically using a 2-dimensional T1-weighted fast field echo pulse MRI sequence before and up to 4 minutes postinjection of Fe-PyC3A. Dynamic imaging was then repeated after an injection of gadobutrol (0.1 mmol/kg) as negative control probe. Rabbits from the 12-week aneurysm group were also imaged before and 20 minutes and 3 hours after injection of Fe-PyC3A using an axial respiratory gated turbo-spin echo (TSE) pulse sequence with motion-sensitized driven equilibrium (MSDE) preparation. The MSDE/TSE imaging was repeated before, immediately after dynamic acquisition (20 minutes postinjection), and 3 hours after injection of gadobutrol. Aneurysmal enhancement ratios (ERs) were calculated by dividing the postinjection aneurysm versus skeletal muscle contrast ratio by the preinjection contrast ratio. After imaging, the aneurysms were excised and inflammatory infiltrate was characterized by fluorometric detection of myeloperoxidase activity and calprotectin immunostaining, respectively. In vitro relaxometry showed that oxidation of Fe-PyC3A by hydrogen peroxide resulted in a 15-fold increase of r1 at 3 T. Relaxometry in the presence of blood plasma showed no more than a 10% increase of r1 , indicating the absence of strong interaction of Fe-PyC3A with plasma proteins. Dynamic imaging with Fe-PyC3A generated little signal enhancement within the blood pool or adjacent muscle but did generate a transient increase in aneurysmal ER that was significantly greater 4 weeks versus 12 weeks after aneurysm induction (1.6 ± 0.30 vs 1.2 ± 0.03, P < 0.05). Dynamic imaging with gadobutrol generated strong aneurysmal enhancement, but also strong enhancement of the blood and muscle resulting in smaller relative ER change. In the 12-week group of rabbits, MSDE/TSE imaging showed that ER values measured immediately after dynamic MRI (20 minutes postinjection) were significantly higher ( P < 0.05) in the case of Fe-PyC3A (1.25 ± 0.06) than for gadobutrol injection (1.03 ± 0.03). Immunohistochemical corroboration using anticalprotectin antibody showed that leukocyte infiltration into the vessel walls and luminal thrombi was significantly higher in the 4-week group versus 12-week aneurysms (123 ± 37 vs 18 ± 7 cells/mm 2 , P < 0.05). Magnetic resonance imaging using Fe-PyC3A injection in dynamic or delayed acquisition modes was shown to generate a higher magnetic resonance signal enhancement in aneurysms that exhibit higher degree of inflammation. The results of our pilot experiments support further evaluation of MRI using Fe-PyC3A as a noninvasive marker of aneurysmal inflammation.

Are Functional Gains Durable After Decompressive Surgery for Cervical Myelopathy?: Commentary on an article by Victor Hin Ting Yick, MBBS, et al.: "Neurological Survivorship Following Surgery for Degenerative Cervical Myelopathy. A Longitudinal Study on 195 Patients".

Commentary In degenerative cervical myelopathy, spine surgeons generally accept the concept that patients will show clinically meaningful improvement after spinal cord decompression. At a minimum, the spine literature and common sense support the notion that cord decompression will at least halt ongoing neurological deterioration. Surgeons may debate the best method of decompression (anterior or posterior) and whether decompression with fusion is necessary, but there is little dissension with regard to the need for a surgical procedure in the setting of moderate to severe myelopathy1. The extent to which early neurological improvement after the surgical treatment of degenerative cervical myelopathy is sustained in the long term is unknown. Using the concept of neurological survivorship and Kaplan-Meier curves, Yick et al. demonstrate that, although most patients improve after decompressive surgery, not all of these good early results are durable. The authors found that as many as 17.9% of patients will see a recurrent decline in neurological function by 10 years, and most of these patients who underwent failed treatment (74.3%) underwent a revision surgical procedure. Given the published high reoperation rates in cervical spine surgery, these results in degenerative cervical myelopathy are not particularly surprising. In a recent minimum 10-year follow-up of anterior cervical fusion in 159 patients, Buttermann reported a 31% reoperation rate2. In the current study, Yick et al. confirm what smaller, short-term studies have suggested: improvement after decompression for degenerative cervical myelopathy is fleeting in many patients and reoperation is common. Such knowledge is valuable when counseling patients both before and after the surgical procedure. In addition to describing the neurological survivorship of these patients, Yick et al. drilled down on the risk factors for failure. Some of these significant risk factors are patient-specific and are not controllable by the surgeon. These factors include renal failure and spinal cord signal change on T2-weighted magnetic resonance imaging sequences. A cord signal change, associated with cellular changes in the cord secondary to severe cord compression, is often irreversible3 and, as seen in the current study, is associated with ongoing declines in neurological function. Other significant risk factors are modifiable. Surgeons can use these factors to modify their surgical management of cervical myelopathy and, hopefully, improve future neurological survivorship. First, and most importantly, surgeons should not be performing suture laminoplasty. Patients treated with this technique had the worst neurological survivorship (31.2%) and tended to experience treatment failure early after the surgical procedure. Second, patients with ossification of the posterior longitudinal ligament did best when decompression was combined with fusion. Surgeons should give strong consideration to including fusion in patients with ossification of the posterior longitudinal ligament to improve outcomes. Conversely, surgeons might consider avoidance of fusion in younger patients with cervical compressive myelopathy. The top risk factor for late neurological decline was adjacent-level stenosis, proximal or distal to a fusion construct. In these patients, perhaps a posterior decompression without fusion or a laminoplasty with plating will result in better neurological survivorship. Yick et al. should be commended for their efforts to publish longer-term neurological outcomes for this complex group of patients. The strengths of the study include a large cohort of 195 patients and a mean follow-up of 76 months. The weaknesses of the study include a retrospective design with many patients (49) excluded because of incomplete follow-up. Furthermore, many of the included patients (37) had a follow-up period shorter than 2 years. Nevertheless, Yick et al. identify important predictive factors for neurological survivorship after surgical treatment of degenerative cervical myelopathy and give surgeons specific pearls to help with surgical planning. A long-term prospective study with a minimum 10-year follow-up is still necessary to define optimal surgical approaches for degenerative cervical myelopathy.

Development of a non-invasive method for testicular toxicity evaluation using a novel compact magnetic resonance imaging system.

In non-clinical animal studies for drug discovery, histopathological evaluation is the most powerful tool to assess testicular toxicity. However, histological analysis is extremely invasive; many experimental animals are needed to evaluate changes in the pathology and anatomy of the testes over time. As an alternative, small animal magnetic resonance imaging (MRI) offers a non-invasive methodology to examine testicular toxicity without radiation. The present study demonstrated the suitability of a new, ready-to-use compact MRI platform using a high-field permanent magnet to assist with the evaluation of testicular toxicity. To validate the utility of the MRI platform, male mice were treated with busulfan (40 mg/kg, intraperitoneal injection). Twenty-eight days after treatment, both testes in busulfan-treated and control mice (n = 6/group) were non-invasively scanned in situ by MRI at 1 tesla. On a T1-weighted 3D gradient-echo MRI sequences (voxel size: 0.23 × 0.23 × 0.50 mm), the total testicular volume in busulfan-treated mice was significantly smaller than in controls. On T1-weighted images, the signal intensity of the testes was significantly higher in busulfan-treated mice than in controls. The mice were sacrificed, and the testes were isolated for histopathological analysis. The weight of the testes in busulfan-treated mice significantly decreased, similar to the results of the non-invasive analysis. Additionally, periodic acid-Schiff stain-positive effusions were observed in the interstitium of the busulfan-treated mouse testes, potentially explaining T1 shortening due to a high concentration of glycoproteinaceous content. The present data demonstrated a rapid evaluation of testicular toxicity in vivo by compact MRI.

A Novel Perspective to Gamma-Knife Radiosurgery for Solitary Meningiomas: Adaptability of Fast Imaging Employing Steady-State Acquisition/Constructive Interference in Steady-State Magnetic Resonance Imaging.

To compare T1-weighted contrast-enhanced (T1+C) with fast imaging employing steady-state acquisition (FIESTA) magnetic resonance imaging (MRI) sequences to protect healthy brain tissue during meningioma treatment with Gamma-Knife radiosurgery (GKRS). After reviewing the data of 54 patients with solitary meningioma who underwent GKRS between January 2020 and June 2022, demographic characteristics were noted, tumor volumes on T1+C and FIESTA MRI sequences were measured, and sequences were compared. The patients were then divided into two groups according to the presence of invasion to intracranial venous sinuses (groups 1 and 2, respectively). SPSS 11.5 software was used for data analysis, with the level of significance set at 0.05. While no significant age and tumor size differences were observed between groups 1 and 2, sinus invasion was significantly higher among males. Tumor volumes measured in both groups were significantly smaller on FIESTA sequences than on T1+C sequences. The T1+C sequence has been the primary imaging method because of meningiomas' high contrast enhancement feature. However, the T1+C sequence during GKRS planning is an effective imaging method in treating meningiomas; FIESTA sequences can more precisely delineate the tumor border. In this study, we consider that using the FIESTA/CISS sequence MRI for planning meningioma therapy with Gamma-Knife can reduce target volume and prevent irradiation of healthy brain tissue.