Sagittal Magnetic Resonance Imaging Research Articles

Improvement of 2D cine image quality using 3D priors and cycle generative adversarial network for low field MRI-guided radiation therapy.

Cine magnetic resonance (MR) images have been used for real-time MR guided radiation therapy (MRgRT). However, the onboard MR systems with low-field strength face the problem of limited image quality. To improve the quality of cine MR images in MRgRT using prior image information provided by the patient planning and positioning MR images. This study employed MR images from 18 pancreatic cancer patients who received MR-guided stereotactic body radiation therapy. Planning 3D MR images were acquired during the patient simulation, and positioning 3D MR images and 2D sagittal cine MR images were acquired before and during the beam delivery, respectively. A deep learning-based framework consisting of two cycle generative adversarial networks (CycleGAN), Denoising CycleGAN and Enhancement CycleGAN, was developed to establish the mapping between the 3D and 2D MR images. The Denoising CycleGAN was trained to first denoise the cine images using the time domain cine image series, and the Enhancement CycleGAN was trained to enhance the spatial resolution and contrast by taking advantage of the prior image information from the planning and positioning images. The denoising performance was assessed by signal-to-noise ratio (SNR), structural similarity index measure, peak SNR, blind/reference-less image spatial quality evaluator (BRISQUE), natural image quality evaluator, and perception-based image quality evaluator scores. The quality enhancement performance was assessed by the BRISQUE and physician visual scores. In addition, the target contouring was evaluated on the original and processed images. Significant differences were found for all evaluation metrics after Denoising CycleGAN processing. The BRISQUE and visual scores were also significantly improved after sequential Denoising and Enhancement CycleGAN processing. In target contouring evaluation, Dice similarity coefficient, centroid distance, Hausdorff distance, and average surface distance values were significantly improved on the enhanced images. The whole processing time was within 20ms for a typical input image size of 512 × 512. Taking advantage of the prior high-quality positioning and planning MR images, the deep learning-based framework enhanced the cine MR image quality significantly, leading to improved accuracy in automatic target contouring. With the merits of both high computational efficiency and considerable image quality enhancement, the proposed method may hold important clinical implication for real-time MRgRT.

MRI phenotypes of herniated discs associated with adjacent disc degeneration.

Adjacent segment degeneration is commonly observed in patients after fusion surgery. Among the associated risk factors is the preoperative presence of adjacent disc degeneration (ADD). The risk factors and other spine phenotypes associated with preoperative ADD is critical to understand the pathological process and better prognosis postsurgery. Current study aims to assess and compare the magnetic resonance imaging(MRI) spinal phenotype of herniated level with and without ADD. Preoperative T2W sagittal lumbar MRI images of 155 lumbar disc herniated patients were analyzed for the presence of ADD (Pfirrmann grade III and above). The herniated disc level was assessed for the presence and absence of vertebral endplate (VEP) defects, Modic changes, and high intensity zone (HIZ). Mean age of patients was 38 ± 2 years, almost 62% were males. ADD was found in 57%, VEP defects were seen in 62% of the herniated level, 24.5% showed Modic changes, 3.8% showed spondylolishthesis, and 15.5% revealed HIZ. Age and other demographic factors did not have any significant effect on the presence of ADD, the patients with extruded andsequestered discs had more ADD (p = 0.02). VEP defects were significantly higher in levels with ADD (p = 0.02). Patients with ADD had significantly VEP defect scores (p = 0.01), Modic score (p = 0.002), HIZ score (0.02), andposterior bulge score (p < 0.001). Findings suggest that affected levels with VEP defects and severe grade of disc herniation have the greater likelihood of having ADD. Once developed this ADD may also affect the other spinal levels, and also can affect postoperative prognosis.

Abdominal Fat is a Reliable Indicator of Lumbar Intervertebral Disc Degeneration than Body Mass Index

The objective of this study was to determine whether abdominal fat status correlates with low back pain (LBP) and lumbar intervertebral disc degeneration (IVDD) and to identify a new anthropometric index to predict the likelihood of developing LBP. Patients with chronic low back pain admitted to the Affiliated Hospital of Southwest Medical University from June 2022 to May 2023 were collected as the experimental group. Volunteers without LBP from June 2022 to May 2023 were also recruited as the control group. They underwent lumbar spine magnetic resonance imaging and had their body mass index (BMI) measured. Abdominal parameters were measured on T2-weighted median sagittal magnetic resonance imaging at the L3/4 level: abdominal diameter, sagittal abdominal diameter (SAD), and subcutaneous abdominal fat thickness (SAFT). Each lumbar IVDD was assessed using the Pfirrmann grading system. The differences in abdominal parameters and BMI between the experimental and control groups were compared, and the correlations between abdominal parameters, BMI, LBP, and IVDD were analyzed. Abdominal diameter, SAD, and SAFT had moderate-to-strong correlations with BMI. SAD was significantly associated with severe IVDD at L4-L5 and L5-S1 levels with odds ratio of 3.201 (95% confidence interval [CI]: 1.850-5.539, P<0.001) and 1.596 (95% CI: 1.072-2.378, P=0.021), respectively. BMI had no significant association with severe IVDD. In women, SAFT and BMI were significantly correlated with LBP; in men, only SAFT was significantly correlated with LBP. Appropriate cutoff values for men and women were 1.52cm (area under the curve=0.702, 95% CI: 0.615-0.789, P < 0.001) and 1.97cm (area under the curve=0.740, 95% CI: 0.662-0.818, P < 0.001), respectively. Men and women with SAFT of >1.52cm and >1.97cm, respectively, had significantly higher rates of LBP. SAD could predict severe IVDD better than BMI. SAFT is a better predictor of LBP than BMI, especially in men, and reliably distinguished patients with LBP from asymptomatic subjects with reliable cutoff values for men and women.

Preoperative examination and intraoperative cerebrospinal fluid leakage test for minimally invasive surgery of spinal extradural arachnoid cysts: illustrative case.

Spinal extradural arachnoid cysts (SEACs) are rare and can cause spinal dysfunction. Total cyst removal and duraplasty via multiple laminectomies are commonly performed. However, to avoid postoperative spinal deformity and axial pain, a minimally invasive surgery via selective laminectomy may be optimal. Therefore, preoperative detection of the dural fistula site is required. A 25-year-old male presented with a 2-month history of progressive gait disturbance and back pain. Conventional magnetic resonance imaging (MRI) revealed SEACs at the T9 to L2 level but did not reveal the dural fistula. Further examinations were performed using sagittal time-spatial labeling inversion pulse MRI and cone-beam computed tomography myelography with a spinal intrathecal catheter, which indicated a dural fistula on the left side at the T12 level. On the basis of these results, dural repair was performed via selective laminectomy. Furthermore, an intraoperative cerebrospinal fluid leakage test by intrathecally injecting saline via a spinal catheter confirmed complete closure of the dural fistula, with no other fistulas. These comprehensive pre and intraoperative examinations may be useful for minimally invasive and selective surgeries in patients with SEACs.

T2 mapping for quantitative assessment of ankle cartilage of weightlifters

The research into the prevention of sports injuries among the population, particularly juveniles, has become crucial due to the increasing participation in physical exercises like fitness. To assess the difference in T2 values of ankle talar cartilage between weightlifters and healthy volunteers using quantitative magnetic resonance imaging (MRI) technique T2 mapping. Study design: Prospective. Prospective evaluation of T2 values of ankle cartilage of 50 weightlifters (30 adults and 20 juveniles) and 100 healthy volunteers (80 adults and 20 juveniles) using Siemens 3.0 T MRI with PDWI, T1WI, and T2 mapping sequences. Three physicians manually divided the talar cartilage of the ankle joint into six regions of interest. Three physicians utilized the anterior and posterior cut edges of the tibial cartilage as markers to identify the corresponding anterior and posterior cut edges of the talar cartilage on the sagittal MRI images. The medial and lateral sides were defined as half of the talar articular surface on the coronal plane. Differences in T2 values in each cartilage region were compared using independent sample T test or Mann–Whitney U test. The T2 values of talar cartilage were significantly increased in the athlete group relative to the volunteer group (35.11 and 31.99, P < 0.001), with the most significant difference observed in the juvenile athlete group compared to the volunteer group (34.42 and 28.73, P < 0.001). There was a significant difference in the T2 value of ankle talar cartilage between weightlifters and healthy volunteers, and juveniles may be more vulnerable to overuse sports injuries. This study contributes to understanding the cartilage health of juvenile athletes and the prevention of sports injuries.

Evaluating the Etiology of Osteochondritis Dissecans of the Knee: The Role of the Articular-Epiphyseal Cartilage Complex

Introduction: In pathologic form, osteochondritis dissecans (OCD) is a focal end-stage disease of articular cartilage. Comparative anatomy studies have demonstrated that injury to epiphyseal anlage cartilage leads to development of OCD in many species, whereas in humans, the exact etiology is suspected but remains unknown. A potential candidate is the articular-epiphyseal cartilage complex, and our hypothesis is that injury at the junction between the epiphyseal anlage cartilage and the articular cartilage results in childhood OCD.Methods: A retrospective, two-institution assessment of children with magnetic resonance imaging (MRI) of the affected knee before the onset of an OCD lesion was performed. Demographics were recorded, including the history of why each initial pre-OCD MRI (Index-MRI) was obtained. MRI measurements were made on the Index-MRI as well as the subsequent OCD-MRI of the epiphyseal ossification length (Growth), marrow edema, the distance of lesion from physis (Lesion Position), and the distance from articular surface (OCD Depth). Comparisons over time were then calculated.Results: Six children (seven knees) were identified with an Index-MRI (Pre-OCD development) obtained at median age 11.6 years and OCD-MRI obtained at a median of 1.9 years later. ‘Growth' occurred in at least one dimension for all children (sagittal MRI, p=0.018). As a group, the ‘Lesion Position' did not change significantly in any plane but two demonstrated continued ossification of the epiphysis and one demonstrated bone necrosis. As a group, the ‘OCD Depth' was significantly different (coronal plane, p=0.029 and sagittal plane, p=0.026) over time, with all lesions increasing their depth (since none existed on the Index-MRI).Discussion: Even though the articular-epiphyseal cartilage complex appeared to be involved with the etiology of knee OCD in this limited series, we found significant variation in the response to a presumed injury with either halted progression, continued ossification, or even regression of ossification adjacent to the OCD. This variation either indicates that there is a multimodal etiology, or that the articular-epiphyseal cartilage complex inconsistently responds to injury. This may explain the inconsistent response to management and calls for further basic science studies to ascertain the exact location of injury in the human articular-epiphyseal cartilage complex.Level of Evidence: III, Retrospective Cohort StudyKey Concepts•Osteochondritis dissecans may have more than one etiology that leads to a similar pathology pattern at the time of presentation.•Future study will be important to identify when certain patterns of progression are present that may indicate one management modality over another one.•Understanding the variation in OCD etiology may have repercussions regarding animal model development.

Microsurgical and fiber tract anatomy of the interthalamic adhesion.

The authors of this study aimed to define the microanatomy of the interthalamic adhesion (ITA) using microfiber dissection, magnetic resonance (MR) tractography, and histological analysis. Sagittal, coronal, and axial MR images from 160 healthy individuals 2-82 years of age were examined. The relationships between age range and ITA morphology as well as between gender and ITA morphology were evaluated statistically. Among these 160 individuals, 100 who had undergone MR tractography were examined. In this group, the presence of fiber tracts in the ITA and the relationship with ITA morphological types were examined. Thirty formalin-fixed human cadaveric brains were also examined endoscopically, and 6 hemispheres were dissected from the medial to lateral and superior to inferior directions under the microscope. Sections taken from one of the brains with an ITA type 2 with both thalami were examined histologically. Anti-neurofilament antibody was used in the histological examination. Four morphological types of ITA were observed. Type 1 had an adhesion/adherent appearance, type 2 had a bridge/commissure appearance, type 3 showed no adhesion, and type 4 had a double bridge. Tractographic examination revealed that 28% had no fiber tract transition in the ITA, 21% had a significant transition, and 51% had an indistinct transition. Statistically, the presence of the ITA was significantly higher in the pediatric (age) and female (gender) groups. In specimens with ITAs of a bridge/commissure appearance (type 2), fiber tracts showed clear transitions between thalami. In type 1 (adherent/adhesive appearance), fiber tracts were observed within the ITA, but a reciprocal transition was unclear. Dissection showed that these fiber tracts in the ITA reach the nucleus accumbens, caudate nucleus, and frontoorbital region anteriorly and the lateral habenula and posterior commissure posteriorly. Some fibers also joined the ansa peduncularis. In histological studies, axonal fibers moving in the ITA were observed with anti-neurofilament antibody staining. This is the first study to demonstrate fiber tracts of the ITA through fiber dissection and transillumination techniques as well as radiological and histological study. Statistical data were obtained by comparing the morphological group with age and gender groups. The anatomy of this structure, which has been neglected for many years, was reexamined. This study showed that the ITA has fibers connecting different parts of the brain, in contrast to previous studies suggesting that it was a simple massa.

A Convolutional Neural Network for Automated Detection of Cervical Ossification of the Posterior Longitudinal Ligament using Magnetic Resonance Imaging.

Retrospective cohort study. We aimed to develop and validate a convolutional neural network (CNN) model to distinguish between cervical ossification of posterior longitudinal ligament (OPLL) and multilevel degenerative spinal stenosis using Magnetic Resonance Imaging (MRI) and to compare the diagnostic ability with spine surgeons. Some artificial intelligence models have been applied in spinal image analysis and many of promising results were obtained; however, there was still no study attempted to develop a deep learning model in detecting cervical OPLL using MRI images. In this retrospective study, 272 cervical OPLL and 412 degenerative patients underwent surgical treatment were enrolled and divided into the training (513 cases) and test dataset (171 cases). CNN models applying ResNet architecture with 34, 50, and 101 layers of residual blocks were constructed and trained with the sagittal MRI images from the training dataset. To evaluate the performance of CNN, the receiver operating characteristic curves of 3 ResNet models were plotted and the area under the curve were calculated on the test dataset. The accuracy, sensitivity, and specificity of the diagnosis by the CNN were calculated and compared with 3 senior spine surgeons. The diagnostic accuracies of our ResNet34, ResNet50, and ResNet101 models were 92.98%, 95.32%, and 97.66%, respectively; the area under the curve of receiver operating characteristic curves of these models were 0.914, 0.942, and 0.971, respectively. The accuracies and specificities of ResNet50 and ResNet101 models were significantly higher than all spine surgeons; for the sensitivity, ResNet101 model achieved better values than that of the 2 surgeons. The performance of our ResNet model in differentiating cervical OPLL from degenerative spinal stenosis using MRI is promising, better results were achieved with more layers of residual blocks applied.

Study on the diagnostic value of different posterior cruciate ligament index measurement methods for anterior cruciate ligament injury

To compare the posterior cruciate ligament(PCL) index with six different measurement methods, and analyze and verify its clinical diagnostic value in anterior cruciate ligament (ACL) injury. The Magnetic resonance imaging (MRI) data of 225 knee joints in our hospital from May 2018 to March 2022 were retrospectively analyzed, aged from 18 to 60 years old, with a median of 32 years old. On the sagittal MRI images of 114 patients with ACL injury and 111 patients with intact ACL, Measure the straight-line distance (A) between the femoral attachment point and the tibial attachment point of the PCL on the MRI sagittal image and the maximum vertical distance (B) between the straight line and the arcuate mark point of the PCL on the sagittal image, calculate the PCL index and evaluate the diagnostic value of the PCL index for ACL injury. The PCL index of the ACL normal group and the ACL injury group were statistically described. There was no significant difference in PCL index 1, 2, 3 and 6 between the two groups(P>0.05). The difference of PCL index 4 and 5 between the two groups was statistically significant (P<0.001). This study only found that the PCL index 2, 6 in the ACL normal group had a negative correlation with the patient's age (correlation coefficient=-0.213, -0.819;P<0.05), and the PCL index 5 in the ACL injury group was significantly correlated with the patient's body mass index(BMI)had a negative correlation (correlation coefficient=-0.277, P<0.05). The change of PCL index is helpful for the diagnosis of ACL injury, PCL index 4 and 5 can be used as effective reference indexes for diagnosing ACL injury in clinic.

Respiratory Diaphragm Motion-Based Asynchronization and Limitation Evaluation on Chronic Obstructive Pulmonary Disease.

Background: Chronic obstructive pulmonary disease (COPD) typically causes airflow blockage and breathing difficulties, which may result in the abnormal morphology and motion of the lungs or diaphragm. Purpose: This study aims to quantitatively evaluate respiratory diaphragm motion using a thoracic sagittal magnetic resonance imaging (MRI) series, including motion asynchronization and limitations. Method: First, the diaphragm profile is extracted using a deep-learning-based field segmentation approach. Next, by measuring the motion waveforms of each position in the extracted diaphragm profile, obvious differences in the independent respiration cycles, such as the period and peak amplitude, are verified. Finally, focusing on multiple breathing cycles, the similarity and amplitude of the motion waveforms are evaluated using the normalized correlation coefficient (NCC) and absolute amplitude. Results and Contributions: Compared with normal subjects, patients with severe COPD tend to have lower NCC and absolute amplitude values, suggesting motion asynchronization and limitation of their diaphragms. Our proposed diaphragmatic motion evaluation method may assist in the diagnosis and therapeutic planning of COPD.

Experimental comparison of linear regression and LSTM motion prediction models for MLC-tracking on an MRI-linac.

Magnetic resonance imaging (MRI)-guided radiotherapy with multileaf collimator (MLC)-tracking is a promising technique for intra-fractional motion management, achieving high dose conformality without prolonging treatment times. To improve beam-target alignment, the geometric error due to system latency should be reduced by using temporal prediction. To experimentally compare linear regression (LR) and long-short-term memory (LSTM) motion prediction models for MLC-tracking on an MRI-linac using multiple patient-derived traces with different complexities. Experiments were performed on a prototype 1.0T MRI-linac capable of MLC-tracking. A motion phantom was programmed to move a target in superior-inferior (SI) direction according to eight lung cancer patient respiratory motion traces. Target centroid positions were localized from sagittal 2D cine MRIs acquired at 4Hz using a template matching algorithm. The centroid positions were input to one of four motion prediction models. We used (1) a LSTM network which had been optimized in a previous study on patient data from another cohort (offline LSTM). We also used (2) the same LSTM model as a starting point for continuous re-optimization of its weights during the experiment based on recent motion (offline+online LSTM). Furthermore, we implemented (3) a continuously updated LR model, which was solely based on recent motion (online LR). Finally, we used (4) the last available target centroid without any changes as a baseline (no-predictor). The predictions of the models were used to shift the MLC aperture in real-time. An electronic portal imaging device (EPID) was used to visualize the target and MLC aperture during the experiments. Based on the EPID frames, the root-mean-square error (RMSE) between the target and the MLC aperture positions was used to assess the performance of the different motion predictors. Each combination of motion trace and prediction model was repeated twice to test stability, for a total of 64 experiments. The end-to-end latency of the system was measured to be (389 ± 15)ms and was successfully mitigated by both LR and LSTM models. The offline+online LSTM was found to outperform the other models for all investigated motion traces. It obtained a median RMSE over all traces of (2.8 ± 1.3)mm, compared to the (3.2 ± 1.9)mm of the offline LSTM, the (3.3 ± 1.4)mm of the online LR and the (4.4 ± 2.4)mm when using the no-predictor. According to statistical tests, differences were significant (p-value <0.05) among all models in a pair-wise comparison, but for the offline LSTM and online LR pair. The offline+online LSTM was found to be more reproducible than the offline LSTM and the online LR with a maximum deviation in RMSE between two measurements of 10%. This study represents the first experimental comparison of different prediction models for MRI-guided MLC-tracking using several patient-derived respiratory motion traces. We have shown that among the investigated models, continuously re-optimized LSTM networks are the most promising to account for the end-to-end system latency in MRI-guided radiotherapy withMLC-tracking.

Significance of the Ancillary Posterior Knee Soft-Tissue Edema Sign in Traumatic Knee Injuries

Introduction/Background: Traumatic soft-tissue injuries of the knee involve a spectrum of pathologies of the soft-tissue envelope, menisci or rupture of supporting tendinous or ligamentous structures. Magnetic resonance imaging (MRI) is an excellent, noninvasive modality to assess these injuries to guide patient management and improve patient outcomes. Objective: To highlight and explore the clinico-radiological significance of posterior knee soft-tissue edema (PKSTO) ancillary sign in traumatic knee injuries. Materials and Methods: MRI of 150 consecutive young adults undergoing within 1 week of an acute knee injury were reviewed. The area of interest behind the knee was specifically assessed for the presence of PKSTO sign. MRI of patients with PKSTO was analyzed further for associated ligament and meniscal injuries. Results: There were 18 patients with PKSTO sign with a mean age of 21.7 years (range 9–39 years). There was a male preponderance. The most common associated injury found was of the anterior cruciate ligament with four patients having multiple injuries. The average volumetric area of PKSTO was 68.5 cm3 (1.5 cm3–486 cm3) with a proportional increase depending on the severity/number of ligamentous or meniscal pathologies. Conclusion: Detection of the PKSTO ancillary sign on sagittal MRI sequences is associated with clinically relevant knee soft-tissue injuries including multi-ligament and meniscal tears.

Utility of the angle between the cervical canal and the anatomical conjugate line for predicting pouch of Douglas obliteration in patients with posterior placenta previa.

Pouch of Douglas obliteration, which prevents exteriorization of the uterus, increases surgical morbidity in patients with placenta previa. We aimed to identify magnetic resonance imaging features that can predict pouch of Douglas obliteration preoperatively. We retrospectively assessed 39 women with posterior placenta previa who underwent magnetic resonance imaging for the preoperative assessment of placenta accreta spectrum. We defined the angle formed by the anatomical conjugate line (based on pelvimetry) and the cervical canal as the cervical inclination angle, which was measured on sagittal T2-weighted magnetic resonance imaging. Subsequently, we analyzed the correlation between the cervical inclination angle and pouch of Douglas obliteration. The median maternal age was 34 years (range, 22-44 years) and 26 (66.7%) women delivered at term. The median cervical inclination angle was 98° (range, 71-128). Pouch of Douglas obliteration was confirmed in six patients (15.4%). The cut-off value of the cervical inclination angle for the prediction of pouch of Douglas obliteration was 102° with a sensitivity of 66.7%, specificity of 78.8%, positive predictive value of 36.4%, and negative predictive value of 92.9% (area under the curve, 0.83). Measuring the cervical inclination angle may help in ruling out an obliteration of the pouch of Douglas. It may also be useful in the operative management of women with posterior placenta previa. However, caution should be exercised when generalizing the results of this study because of the small sample size, which makes the results prone to bias.

Anteater nose sign and reverse anteater nose sign: Are they specific for calcaneonavicular coalition?

The anteater nose sign has been described on imaging in the case of the calcaneonavicular coalition and is produced by a tubular elongation of the anterior calcaneal process that approaches or overlaps the navicular bone, resembling an anteater’s nose. Similarly, the reverse anteater sign refers to the posterior and lateral extension of the navicular bone, also seen in the case of the calcaneonavicular coalition. Originally described on lateral or oblique foot/ankle radiographs, this appearance is also observed in the case of magnetic resonance images (MRI) on sagittal sections. We describe a case of a talocalcaneal coalition, in which the MRI had a similar appearance, thereby confusing the imaging findings of the case, and discuss the key imaging features for the correct diagnosis. We also propose a new sign, “Opposing beak sign,” for this similar appearance in the case of a talo-calcaneal coalition, awareness of which as a distinct entity on sagittal MRI would help correct preoperative diagnosis and subsequent management.

Predictive factors for conversion from conservatively to surgically treatment osteoporotic thoracolumbar compression fractures based on sagittal parameters and magnetic resonance imaging features.

To investigate the relationship between sagittal plane characteristics of the spinal column and conservative treatment failure in acute osteoporotic spinal fractures (OSFs). As a retrospective study of single-institute data, thoracolumbar OSF patients with similar propensities in terms of location of fractures and results of bone mineral density were analyzed. Among them, 43 patients (group I) who needed reconstructive surgical interventions and 39 patients (group II) who obtained successful treatment through conservative care were included. General demographic data, radiographic features of fractures, and magnetic resonance imaging (MRI) features of fractures were analyzed. To investigate the relationship between global sagittal alignment of the spine and occurrence of delayed complication following OSFs, radiological sagittal parameters were analyzed. The number of cases requiring reconstructive surgery was significantly higher when the index vertebra showed diffuse or mid-portion bone marrow changes in MRI. In terms of sagittal parameters, pelvic incidence (group I 59.1° ± 11.9°, group II 54.6° ± 9.8°) and thoracolumbar angle (group I 26.5° ± 14.1°, group II 17.4° ± 11.2°) were significantly higher in group I. Logistic regression analysis showed that higher pelvic incidence (OR 1.09, 95% CI 1.01-1.18, p value < 0.05) and higher thoracolumbar angle (OR 1.09, 95% CI 1.02-1.17, p value < 0.05) were significant risk factors for delayed complications requiring reconstructive surgery following OSFs. Delayed complications requiring reconstructive surgery following OSFs are related to sagittal plane parameters of the spine such as high pelvic incidences, in addition to previously known radiographic characteristics of fractures.

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.

Magnetic Resonance Imaging Analysis Demonstrates Improved Reliability in Measuring Shoulder Glenoid Bone Loss Using a Two-Thirds Glenoid Height Technique Compared to the “Best-fit Circle”

To evaluate the superior to inferior glenoid height as a reliable reference in best-fit circle creation for glenoid anatomy. The morphology of the native glenoid was evaluated using magnetic resonance imaging (MRI) in patients without shoulder instability. Using T1 sagittal MRI images, two reviewers independently estimated glenoid size using the two-thirds technique and the "best-fit circle" technique at two different times. A student's t-test was used to determine significant difference between the two methodologies. Inter- and intra-rater reliability were calculated using interclass and intraclass coefficients. This study included 112 patients. Using the results of glenoid height and "best-fit circle" diameter, the diameter of the "best-fit circle" was found to intersect the glenoid line at 67.8% of the glenoid height on average. We found no significant difference between the two measures of glenoid diameter (27.6 vs 27.9, p =.456). The interclass and intraclass coefficients for the two-third method were 0.85 and 0.88, respectively. The inter-class and intra-class coefficients for the perfect circle methods were 0.84 and 0.73, respectively. We determined that the diameter of a circle placed on the inferior glenoid using the 'best-fit circle' technique corresponds to 67.8% of the glenoid height. Additionally, we found that constructing a perfect circle using a diameter equal to two-thirds the height of the glenoid may improve intra-class reliability.

Paper 38: Addition of a Lateral Extra-articular Tenodesis is Associated with Lower Quadriceps Tendon Autograft MRI Signal Intensity Two Years Following Anterior Cruciate Ligament Reconstruction in Skeletally Immature Adolescents

Objectives: In recent studies, quadriceps tendon autograft (QTA) has been shown to yield promising results in the treatment of anterior cruciate ligament (ACL) ruptures in pediatric and adolescent patients. Additionally, lateral extra-articular tenodesis (LET) has been found to reduce the risk of ACL re-tear in high-risk patients when performed concomitantly with ACL reconstruction (ACLR). The purpose of this study was to evaluate graft maturity two years after ACLR by comparing magnetic resonance imaging (MRI) signal intensity ratio (SIR) of QTA in patients that underwent a primary ACL reconstruction with a concomitant LET versus patients without a concomitant LET. Methods: After institutional review board approval, operative records of all pediatric patients ≤ 18 years old who underwent an ACLR from June 2015 to December 2021 were retrospectively reviewed. MRIs were ordered for this age cohort of patients for clinical growth plate surveillance. Patients were included if they underwent an ACLR using a QTA and had open distal femoral and proximal tibial physes. MRIs were excluded if they were external or were ordered due to a new injury. The final cohort included 28 patients: 13 without a LET (ACLR only) and 15 with a LET (ACLR+LET). Signal intensity ratio (SIR) was measured on sagittal MRI by averaging the signal at three regions of interest along the ACL graft and dividing by the signal of the insertion of the posterior cruciate ligament. Statistical analysis was performed to evaluate for differences in SIR values at 6 months, 1 year, and 2 years post-operatively in skeletally immature patients undergoing ACLR alone versus ACLR with LET. Results: A total of 43 patients had an MRI at a two-year follow-up, 28 of whom were included in the study. The mean age of the complete cohort was 12.63±3.62 years (ACLR+LET: 13.96±0.91 years vs. ACLR only: 13.51±1.19 years). There were no significant differences in SIR between groups on the 6-month MRI or the 12-month MRI. However, the average SIR of the ACLR+LET group was significantly lower than the average SIR of the ACLR-only group at the two-year post-operative time point (1.398 vs. 1.916, respectively, p=0.046). Conclusions: QTA MRI signal intensity is lower two years after surgery in patients that underwent ACLR with a LET versus ACLR alone. Lower MRI signal intensity correlates with increased graft maturity and structural integrity. These findings suggest improved graft maturation, remodeling, and structural integrity with the addition of a LET to an ACLR with QTA in skeletally immature patients. [Table: see text]

Poster 276: Assessment of Trochlear Cartilage Thickness and Volume Using Sagittal Magnetic Resonance Images to Quantify Trochlear Dysplasia: A Matched-Cohort Study

Objectives: Trochlear dysplasia is considered a major contributing factor for patellar instability. More recently, trochleoplasty procedures have become popularized to address this morphological abnormality. Both thick and thin flap trochleoplasty techniques exist, with the goal to deepen the trochlea while avoiding perforation of the trochlear cartilage during the procedure. However, the relative cartilage thickness in the dysplastic trochlea has not been well described. This study aimed to assess trochlear cartilage thickness and volume in knees with and without patellar instability and the relationship to measurements of trochlear dysplasia. Methods: 25 knees with symptomatic patellar instability were compared with 25 gender-matched knees. Retrospective chart review was performed to obtain demographic data. On sagittal images, trochlear cartilage thickness (TCT) and trochlear cartilage volume (TCV) were analyzed at the center, medial border, and lateral border of the trochlea. TCT was defined as the cartilage thickness halfway along the trochlear length at its maximum dimension. TCV was defined by total area of cartilage proximal to the plane of the intercondylar midpoint. Symptomatic and control values were compared using paired sample t-test. Stepwise multivariate linear regression was performed to assess for associations with standard radiographic parameters of trochlear dysplasia. Results: TCT was significantly different between the medial, central and lateral trochlea in both the symptomatic and control groups (p&lt;0.001). Only lateral TCT demonstrated a significant difference between groups, which was 20.3% (p=0.035) thicker in the symptomatic cohort compared to controls. No significant differences existed in TCV between symptomatic and control groups. In females, central TCT was 28.3% thicker in the symptomatic cohort (p=0.024), while medial TCV was 2.3x greater (p = 0.019). Males failed to demonstrate gender specific differences. Regression analysis demonstrated that patient height showed a significant relationship with all measurements except for medial TCV. Central TCT demonstrated a significant, independent relationship with trochlear depth (Coefficient 0.38, p = 0.011), while central TCV demonstrated a significant, independent relationship with trochlear depth (Coefficient 9.9, p &lt;0.001), sulcus angle (Coefficient 1.1, p &lt;0.001), and lateral trochlear inclination (Coefficient -1.1, p &lt;0.001). Conclusions: While trochlear dysplasia typically refers to abnormal bony morphology, this study demonstrates the role of differential contributions of chondral thickness and volume between knees with and without patellar instability, and that these measurements correlated with severity of dysplasia. Future studies should further investigate the relationship between TCT and TCV with other dysplasia parameters to better inform the surgical considerations of performing trochleoplasty in the treatment of patellar instability. [Table: see text]

Association of Trochlear Length on Sagittal MRI to Trochlear Dysplasia in Knees With Patellar Instability.

Trochlear dysplasia is a primary risk factor for patellar instability and leads to loss of the osteochondral constraint of the patella. Trochleoplasty techniques include the Peterson grooveplasty, which alters the length of the trochlea; however, a radiographic measurement of trochlear length to support this has not been described. To describe measurements to quantify trochlear length on sagittal magnetic resonance imaging in patients with and without patellar instability and to correlate trochlear length with measurements of trochlear dysplasia. Cross-sectional study; Level of evidence, 3. A total of 66 age- and sex-matched knees (36 female and 30 male; mean age, 20.8 ± 4.8 years) were included in this study, of which 33 had patellar instability. Trochlear extension length (TEL) and trochlear alpha angle (TAA) were measured on 3 sagittal magnetic resonance imaging scans (center of the knee, center of the medial condyle, and center of the lateral condyle), and measurements were compared between symptomatic and control knees. Receiver operating characteristic curve analysis was performed, and the area under the curve (AUC) was calculated to describe the accuracy of each measurement to distinguish between knees with and without patellar instability. Linear and multivariate regression analyses were performed to assess the relationship between sagittal measurements and axial measurements of trochlear dysplasia, including lateral trochlear inclination, sulcus angle, and trochlear depth, as well as patient size reflected by the epicondylar distance. In symptomatic knees, the central trochlea extended more proximally than in control knees, as determined by the TEL (14.0 ± 3.0 vs 11.5 ± 2.3 mm, respectively; P < .001) and TAA (68.4° ± 3.8° vs 70.5° ± 3.4°, respectively; P = .017). AUC calculations showed that a TEL ≥11 mm at the central trochlea was predictive of patellar instability in both male and female knees (AUC = 0.83 and 0.77, respectively), as was a TAA ≤67° in female knees (AUC = 0.72). An independent association between the central TEL and sulcus angle was found. The central TEL showed a weak correlation with patient size, as measured by the epicondylar distance, while the TAA did not. In knees with symptomatic patellar instability, the central trochlea was found to extend 2.5 mm more proximally than in control knees, and this increase in length correlated with severity of trochlear dysplasia. As radiographic examinations of the trochlea and grooveplasty procedures are often based on the proximal extent of the cartilaginous trochlea, further studies are needed to identify the role of trochlear length in the assessment and treatment of trochlear dysplasia in the setting of patellar instability.