High-resolution ultrasound of the paratenon of the Achilles calcaneal tendon: anatomical study and description of the paratendinous injection technique.

PURPOSE: The aim of this study is to determine if ultrasound (US) allows a precise assessment of the paratenon (PT) of the Achilles calcaneal tendon (AT), and to anatomically describe the US-guided paratendinous injection technique. METHODS: This study was initially conducted on eight cadaveric specimens using high-resolution ultrasound (HRUS) to examine the PT appearance, thickness, and its relationships with the AT, plantaris tendon (PLT), Kager's fat pad (KFP), sural nerve (SN), and fascia cruris (FC). US-guided paratendinous injection of China ink was performed in all specimens, followed by anatomical dissection to assess injectate distribution. Then, HRUS study of the PT was carried out bilaterally in twenty asymptomatic volunteers (40 legs). Two musculoskeletal radiologists recorded all data in consensus except PT thickness in volunteers which was recorded independently in order to calculate intra and inter-observer reliability. RESULTS: The PT was consistently identified with HRUS along its entire course in both cadaveric specimens (8/8) and volunteers (40/40). The mean PT thickness was 0.54 mm in cadavers and 0.39 mm in vivo, without any correlation with the AT thickness. Intra- and inter observer reliability were respectively excellent and good for PT thickness. All eight (100%) ex vivo China ink injections were accurate, demonstrating a circumferential distribution of the injectate between the PT and the AT, associated with an anterior spread to the KFP. CONCLUSION: HRUS allows visualization of the PT along its entire length, and assessment of its relationships to adjacent structures. US-guided paratendinous injections can accurately and safely deliver injectates in the paratendinous sheath.

Chemotherapy and adjuvant therapies' impact on the internal remodeling process of bone and its mechanical behavior for breast cancer patients.

Breast cancer is a significant public health issue affecting women worldwide. While advancements in treatment options have led to improved survival rates, the impact of breast cancer and its treatments on bone health cannot be overlooked. Bone remodeling is a complex process regulated by the delicate balance between bone formation and resorption. Any disruption to this balance can lead to decreased bone density, increased fracture risk, and compromised physical function. To investigate the effects of breast cancer and its treatments on bone remodeling, a finite element model was developed in this study. This model incorporated bone remodeling equations to simulate the mechanical behavior of bone under different conditions. The ABAQUS/UMAT software was used to simulate the behavior of bone tissue under the influence of breast cancer and treatments. Our findings suggest that bone loss is more pronounced after secondary breast cancer and treatment, leading to bone loss (6%-19% decrease in BV/TV), reduced bone stimulation, and decreased effectiveness of physical activity on recovery. These results highlight the importance of early intervention and management of bone health in breast cancer patients to mitigate the negative impact of cancer and treatment on bone remodeling.

French community grid for the evaluation of radiological artificial intelligence solutions (DRIM France Artificial Intelligence Initiative).

PURPOSE: The purpose of this study was to validate a national descriptive and analytical grid for artificial intelligence (AI) solutions in radiology. MATERIALS AND METHODS: The RAND-UCLA Appropriateness Method was chosen by expert radiologists from the DRIM France IA group for this statement paper. The study, initiated by the radiology community, involved seven steps including literature review, template development, panel selection, pre-panel meeting survey, data extraction and analysis, second and final panel meeting, and data reporting. RESULTS: The panel consisted of seven software vendors, three for bone fracture detection using conventional radiology and four for breast cancer detection using mammography. A consensus was reached on various aspects, including general target, main objective, certification marking, integration, expression of results, forensic aspects and cybersecurity, performance and scientific validation, description of the company and economic details, possible usage scenarios in the clinical workflow, database, specific objectives and targets of the AI tool. CONCLUSION: The study validates a descriptive and analytical grid for radiological AI solutions consisting of ten items, using breast cancer and bone fracture as an experimental guide. This grid would assist radiologists in selecting relevant and validated AI solutions. Further developments of the grid are needed to include other organs and tasks.

Infectious sacroiliitis: MRI- and CT-based assessment of disease extent, complications, and anatomic correlation.

OBJECTIVE: To describe the frequency of MR and CT features of infectious sacroiliitis (ISI) and assess its extent and complications MATERIALS AND METHODS: This retrospective study included patients with ISI who were evaluated between 2008 and 2021 in a single center. Two radiologists reviewed MRI and CT images to determine the anatomical distribution (unilateral/bilateral, iliac/sacral bone, proximal/middle/distal), severity (bone marrow edema [BME]/periostitis/erosions), concurrent infection (vertebral/nonvertebral), and complications (abscess/probable adjacent osteomyelitis/cavitation/devitalized areas/sequestrum/pelvic venous thrombosis) of ISI. Interobserver reproducibility was assessed. Correlation analysis evaluated the effect of the causative microorganism on severity. Two human bodies were dissected to outline possible ways that ISI can spread. RESULTS: Forty patients with ISI (40 years ± 22; 26 women) were evaluated. Ten patients had bilateral ISI. Concurrent vertebral infection was associated in 15% of cases. Reproducibility of sacral BME, periostitis, and reactive locoregional abnormalities was perfect (κ = 1). Reproducibility was low for erosion count (κ = 0.52[0.52-0.82]) and periarticular osteopenia (κ = 0.50[0.18-0.82]). Inflammatory changes were BME (42/42 joints), muscle edema (38/42), and severe periostitis along the ilium (33/37). Destructive structural changes occurred with confluent erosions (iliac, 20/48; sacral, 13/48), sequestrum (20/48), and cavitation (12/48). Complications occurred in 75% of cases, including periarticular abscesses (n = 30/47), probable adjacent osteomyelitis (n = 16/37), and pelvic thrombophlebitis (n = 3). Tuberculous ISI (6/40) correlated with sclerosis (rs = 0.45[0.16; 0.67]; p < 10-2) and bone devitalization (rs = 0.38[0.16; 0.67]; p = .02). The anatomical study highlighted the shared venous vascularization of sacroiliac joints, pelvic organs, and mobile spine. CONCLUSION: Complications of ISI are frequent, including abscesses, adjacent osteomyelitis, and periostitis. ISI had bilateral involvement nonrarely and is commonly associated with another spinal infection.

Opportunistic Computed Tomography Screening for Osteoporosis and Fracture.

Osteoporosis is underdiagnosed and undertreated, leading to loss of treatment for the patient and high costs for the health care system. Routine thoracic and/or abdominal computed tomography (CT) performed for other indications can screen opportunistically for osteoporosis with no extra cost, time, or irradiation. Various methods can quantify fracture risk on opportunistic clinical CT: vertebral Hounsfield unit bone mineral density (BMD), usually of L1; BMD measurement with asynchronous or internal calibration; quantitative CT; bone texture assessment; and finite element analysis. Screening for osteoporosis and vertebral fractures on opportunistic CT is a promising approach, providing automated fracture risk scores by means of artificial intelligence, thus enabling earlier management.

Ultra-high field magnetic resonance imaging of the quadriceps tendon enthesis in healthy subjects.

PURPOSE: Although enthesitis is a hallmark of several rheumatologic conditions, current imaging methods are still unable to characterize entheses changes because of the corresponding short transverse relaxation times (T2). A growing number of MR studies have used Ultra-High Field (UHF) MRI in order to assess low-T2 tissues e.g., tendon but never in humans. The purpose of the present study was to assess in vivo the enthesis of the quadriceps tendon in healthy subjects using UHF MRI. METHODS: Eleven healthy subjects volunteered in an osteoarthritis imaging study. The inclusion criteria were: no knee trauma, Lequesne index = 0, less than 3 h of sport activities per week, and Kellgren and Lawrence grade = 0. 3D MR images were acquired at 7 T using GRE sequences and a T2* mapping. Regions of interest i.e., trabecular bone, subchondral bone, enthesis, and tendon body were identified, and T2* values were quantified and compared. RESULTS: Quadriceps tendon enthesis was visible as a hyper-intense signal. The largest and the lowest T2* values were quantified in the subchondral bone region and the tendon body respectively. T2* value within subchondral bone was significantly higher than T2* value within the enthesis. T2* in subchondral bone region was significantly higher than the whole tendon body T2*. CONCLUSION: A T2* gradient was observed along the axis from the enthesis toward the tendon body. It illustrates different water biophysical properties. These results provide normative values which could be used in the field of inflammatory rheumatologic diseases and mechanical disorders affecting the tendon.

Anatomical study of the medial calcaneal nerve using high-resolution ultrasound.

OBJECTIVES: To determine whether high-resolution ultrasound (US) can identify the course and relations of the medial calcaneal nerve (MCN). METHODS: This investigation was initially undertaken in eight cadaveric specimens and followed by a high-resolution US study in 20 healthy adult volunteers (40 nerves) by two musculoskeletal radiologists in consensus. The location and course of the MCN as well as its relationship to adjacent anatomical structures were evaluated. RESULTS: The MCN was consistently identified by US along its entire course. The mean cross-sectional area of the nerve was 1 mm2 (range 0.5-2). The level at which the MCN branched from the tibial nerve was variable, located a mean of 7 mm (range - 7-60) proximal to the tip of the medial malleolus. At the level of the medial retromalleolar fossa, the MCN was located inside the proximal tarsal tunnel a mean of 8 mm (range 0-16) posterior to the medial malleolus. More distally, the nerve was depicted in the subcutaneous tissue at the surface of the abductor hallucis fascia with a mean direct distance to the fascia of 1.5 mm (range 0.4-2.8). CONCLUSIONS: High-resolution US can identify the MCN at the level of the medial retromalleolar fossa, as well as more distally in the subcutaneous tissue at the surface of the abductor hallucis fascia. In the setting of heel pain, precise sonographic mapping of the MCN course may enable the radiologist to make diagnosis of nerve compression or neuroma, and perform selective US-guided treatments. CLINICAL RELEVANCE STATEMENT: In the setting of heel pain, sonography is an attractive tool for diagnosing compression neuropathy or neuroma of the medial calcaneal nerve, and enables the radiologist to perform selective image-guided treatments such as diagnostic blocks and injections. KEY POINTS: • The MCN is a small cutaneous nerve which rises from the tibial nerve in the medial retromalleolar fossa to the medial side of the heel. • The MCN can be depicted by high-resolution ultrasound along its entire course. • In the setting of heel pain, precise sonographic mapping of the MCN course may enable the radiologist to make diagnosis of neuroma or nerve entrapment, and perform selective ultrasound-guided treatments such as steroid injection or tarsal tunnel release.

Automatic deep learning-based assessment of spinopelvic coronal and sagittal alignment.

PURPOSE: The purpose of this study was to evaluate an artificial intelligence (AI) solution for estimating coronal and sagittal spinopelvic alignment on conventional uniplanar two-dimensional whole-spine radiograph. MATERIAL AND METHODS: This retrospective observational study included 100 patients (35 men, 65 women) with a median age of 14 years (IQR: 13, 15.25; age range: 3-64 years) who underwent conventional uniplanar two-dimensional whole-spine radiograph in standing position between January and July 2022. Ten most commonly used spinopelvic coronal and sagittal parameters were retrospectively measured without AI by a junior radiologist and approved or adjusted by a senior musculoskeletal radiologist to reach final measurements. Final measurements were used as the ground truth to assess AI performance for each parameter. AI performances were estimated using mean absolute errors (MAE), intraclass correlation coefficient (ICCs), and accuracy for selected clinically relevant thresholds. Readers visually classified AI outputs to assess reliability at a patient-level. RESULTS: AI solution showed excellent consistency without bias in coronal (ICCs ≥ 0.95; MAE ≤ 2.9° or 1.97 mm) and sagittal (ICCs ≥ 0.85; MAE ≤ 4.4° or 2.7 mm) spinopelvic evaluation, except for kyphosis (ICC = 0.58; MAE = 8.7°). AI accuracy to classify low Cobb angle, severe scoliosis or frontal pelvic asymmetry was 91% (95% CI: 85-96), 99% (95% CI: 97-100) and 94% (95% CI: 89-98), respectively. Overall, AI provided reliable measurements in 72/100 patients (72%). CONCLUSION: The AI solution used in this study for combined coronal and sagittal spinopelvic balance assessment provides results consistent with those of a senior musculoskeletal radiologist, and shows potential benefit for reducing workload in future routine implementation.

Vertebral trabecular bone texture analysis in opportunistic MRI and CT scan can distinguish patients with and without osteoporotic vertebral fracture: A preliminary study.

PURPOSE: To investigate the potential of texture parameters from opportunistic MRI and CT for the detection of patients with vertebral fragility fracture, to design a decision tree and to compute a Random Forest analysis for the prediction of fracture risk. METHODS: One hundred and eighty vertebrae of sixty patients with at least one (30) or without (30) a fragility fracture were retrospectively assessed. Patients had a DXA, an MRI and a CT scan from the three first lumbar vertebrae. Vertebrae texture analysis was performed in routine abdominal or lumbar CT and lumbar MRI using 1st and 2nd order texture parameters. Hounsfield Unit Bone density (HU BD) was also measured on CT-scan images. RESULTS: Twelve texture parameters, Z-score and HU BD were significantly different between the two groups whereas T score and BMD were not. The inter observer reproducibility was good to excellent. Decision tree showed that age and HU BD were the most relevant factors to predict the fracture risk with a 93 % sensitivity and 56 % specificity. AUC was 0.91 in MRI and 0.92 in CT-scan using the Random Forest analysis. The corresponding sensitivity and specificity were 72 % and 93 % in MRI and 83 and 89 % in CT. CONCLUSIONS: This study is the first to compare texture indices computed from opportunistic CT and MR images. Age and HU-BD together with selected texture parameters could be used to assess risk fracture. Machine learning algorithm can detect fracture risk in opportunistic CT and MR imaging and might be of high interest for the diagnosis of osteoporosis.

Texture Parameters Measured by UHF-MRI and CT Scan Provide Information on Bone Quality in Addition to BMD: A Biomechanical Ex Vivo Study.

The current definition of osteoporosis includes alteration of bone quality. The assessment of bone quality is improved by the development of new texture analysis softwares. Our objectives were to assess if proximal femoral trabecular bone texture measured in Ultra high field (UHF) 7 Tesla MRI and CT scan were related to biomechanical parameters, and if the combination of texture parameters and areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry provided a better prediction of femoral failure than aBMD alone. The aBMD of 16 proximal femur ends from eight cadavers were investigated. Nineteen textural parameters were computed in three regions or volumes of interest for each specimen on UHF MRI and CT scan. Then, the corresponding failure load and failure stress were calculated thanks to mechanical compression test. aBMD was not correlated to failure load (R2 = 0.206) and stress (R2 = 0.153). The failure load was significantly correlated with ten parameters in the greater trochanter using UHF MRI, and with one parameter in the neck and the greater trochanter using CT scan. Eight parameters in the greater trochanter using UHF MRI combined with aBMD improved the failure load prediction, and seven parameters improved the failure stress prediction. Our results suggest that textural parameters provide additional information on the fracture risk of the proximal femur when aBMD is not contributive.

Multiscale Femoral Neck Imaging and Multimodal Trabeculae Quality Characterization in an Osteoporotic Bone Sample.

Although multiple structural, mechanical, and molecular factors are definitely involved in osteoporosis, the assessment of subregional bone mineral density remains the most commonly used diagnostic index. In this study, we characterized bone quality in the femoral neck of one osteoporotic patients as compared to an age-matched control subject, and so used a multiscale and multimodal approach including X-ray computed microtomography at different spatial resolutions (pixel size: 51.0, 4.95 and 0.9 µm), microindentation and Fourier transform infrared spectroscopy. Our results showed abnormalities in the osteocytes lacunae volume (358.08 ± 165.00 for the osteoporotic sample vs. 287.10 ± 160.00 for the control), whereas a statistical difference was found neither for shape nor for density. The osteoporotic femoral head and great trochanter reported reduced elastic modulus (Es) and hardness (H) compared to the control reference (−48% (p < 0.0001) and −34% (p < 0.0001), respectively for Es and H in the femoral head and −29% (p < 0.01) and −22% (p < 0.05), respectively for Es and H in the great trochanter), whereas the corresponding values in the femoral neck were in the same range. The spectral analysis could distinguish neither subregional differences in the osteoporotic sample nor between the osteoporotic and healthy samples. Although, infrared spectroscopic measurements were comparable among subregions, and so regardless of the bone osteoporotic status, the trabecular mechanical properties were comparable only in the femoral neck. These results illustrate that bone remodeling in osteoporosis is a non-uniform process with different rates in different bone anatomical regions, hence showing the interest of a clear analysis of the bone microarchitecture in the case of patients' osteoporotic evaluation.

Experimental-based mechanobiological modeling of the anabolic and catabolic effects of breast cancer on bone remodeling.

Bone is a biological tissue characterized by its hierarchical organization. This material has the ability to be continually renewed, which makes it highly adaptative to external loadings. Bone renewing is managed by a dynamic biological process called bone remodeling (BR), where continuous resorption of old bone and formation of new bone permits to change the bone composition and microstructure. Unfortunately, because of several factors, such as age, hormonal imbalance, and a variety of pathologies including cancer metastases, this process can be disturbed leading to various bone diseases. In this study, we have investigated the effect of breast cancer (BC) metastases causing osteolytic bone loss. BC has the ability to affect bone quantity in different ways in each of its primary and secondary stages. Based on a BR mathematical model, we modeled the BC cells' interaction with bone cells to assess their effect on bone volume fraction (BV/TV) evolution during the remodeling process. Some of the parameters used in our model have been determined experimentally using the enzyme-linked immune-sorbent assay (ELISA) and the MTT assay. Our numerical simulations show that primary BC plays a significant role in enhancing bone-forming cells' activity leading to a 6.22% increase in BV/TV over 1 year. On the other hand, secondary BC causes a noticeable decrease in BV/TV reaching 15.74% over 2 years.

Assessment of Bone Microarchitecture in Fresh Cadaveric Human Femurs: What Could Be the Clinical Relevance of Ultra-High Field MRI.

MRI could be applied for bone microarchitecture assessment; however, this technique is still suffering from low resolution compared to the trabecular dimension. A clear comparative analysis between MRI and X-ray microcomputed tomography (µCT) regarding microarchitecture metrics is still lacking. In this study, we performed a comparative analysis between µCT and 7T MRI with the aim of assessing the image resolution effect on the accuracy of microarchitecture metrics. We also addressed the issue of air bubble artifacts in cadaveric bones. Three fresh cadaveric femur heads were scanned using 7T MRI and µCT at high resolution (0.051 mm). Samples were submitted to a vacuum procedure combined with vibration to reduce the volume of air bubbles. Trabecular interconnectivity, a new metric, and conventional histomorphometric parameters were quantified using MR images and compared to those derived from µCT at full resolution and downsized resolutions (0.102 and 0.153 mm). Correlations between bone morphology and mineral density (BMD) were evaluated. Air bubbles were reduced by 99.8% in 30 min, leaving partial volume effects as the only source of bias. Morphological parameters quantified with 7T MRI were not statistically different (p > 0.01) to those computed from µCT images, with error up to 8% for both bone volume fraction and trabecular spacing. No linear correlation was found between BMD and all morphological parameters except trabecular interconnectivity (R2 = 0.69 for 7T MRI-BMD). These results strongly suggest that 7T MRI could be of interest for in vivo bone microarchitecture assessment, providing additional information about bone health and quality.

Ultrasound-Guided Perimeniscal Injections: Anatomical Description and Feasibility Study.

OBJECTIVES: To anatomically describe the ultrasound (US)-guided perimeniscal injection technique, and evaluate its feasibility in the treatment of meniscal pain. METHODS: This work was initially undertaken in four cadaveric specimens with US-guided medial and lateral perimeniscal injection of China ink, followed by cadaveric dissection to assess injectate distribution, and potential injury to intra-articular and peri-articular structures. Then, 35 consecutive patients who underwent US-guided perimeniscal corticosteroid injection under local anesthesia for the treatment of symptomatic medial (30/35) or lateral (5/35) degenerative meniscal tear were retrospectively evaluated. Clinical outcome was assessed using a 0-10 numerical verbal rating scale (VRS) to evaluate severity of pain before, during, and after procedure at 6 weeks follow-up. RESULTS: Seven of eight (87.5%) ex vivo injections were accurate. A single inaccurate medial perimeniscal injection infiltrated the tibial collateral ligament instead of the perimeniscal area. No anatomical specimen exhibited intrameniscal injection or injury to regional structures. All procedures (35/35) performed clinically were technically successful. Median VRS scores were: 7 (range, 3-9) before procedure, 5 (range, 0-10) during procedure, and 1.5 (range, 0-9) after procedure at 6 weeks follow-up (P <.0001). No complication was observed. CONCLUSIONS: US-guided perimeniscal injections can accurately and safely deliver injectates in the perimeniscal area. In addition, our data suggest that perimeniscal corticosteroid injection provides significant symptom relief at 6 weeks in patients with meniscal pain. Further studies with long-term follow-up will be required to evaluate the role of perimeniscal injections in the nonoperative management of meniscal pathology.

Intradiscal oxygen-ozone therapy for the treatment of symptomatic lumbar disc herniation: A preliminary study.

PURPOSE: To assess safety and effectiveness of computed tomography (CT)-guided intradiscal oxygen-ozone therapy (O2-O3 therapy) for the treatment of symptomatic lumbar disc herniation and radiological changes. MATERIALS AND METHODS: This study was conducted in twenty patients presenting lumbar disc herniation with resistant lumbar or lumbar radicular pain They underwent intradiscal oxygen-ozone therapy under CT guidance. They were treated at one- or two-disc levels, representing a total of 24 discs treated. MR imaging examinations were obtained before treatment and 2 months post-procedure to analyse treatment-related disc modifications including modification of the surfaces of the disc and of the herniated disc, and the variations in disc height according to the disc height index. Clinical outcomes were assessed using the visual analogue scale (VAS) to evaluate the severity of pain before the procedure, at primary (2 months) and at secondary (12 months) follow-ups. RESULTS: All the procedures were technically successful. The median VAS scores were 7.95 before the procedure, 3.9 at 2 months and 2.95 at 12 months. MRI analysis showed a significant decrease in herniation size at 2 months (-20%, p = 0.008). No immediate or late complications were observed. Only three patients (13.6%) underwent lumbar spine microdiscectomy in the year following ozone therapy. The treatment appeared to be more effective in cases of nerve root symptomatology. CONCLUSION: This study suggests that intradiscal O2-O3 therapy is safe and effective for the treatment of lumbar disc herniation associated with resistant lumbar or lumbar radicular pain.

Osteoid Osteoma: Percutaneous CT-guided Cryoablation Is a Safe, Effective, and Durable Treatment Option in Adults.

Background Cryoablation is playing an increasing role in the percutaneous treatment of bone tumors. However, despite its potential advantages over heat-based ablation techniques, the clinical safety and efficacy of cryoablation have not been established for osteoid osteoma treatment. Purpose To evaluate percutaneous CT-guided cryoablation for the treatment of osteoid osteoma in young patients and adults. Materials and Methods This retrospective study reviewed data from 50 consecutive patients who underwent percutaneous CT-guided cryoablation for the treatment of osteoid osteoma between January 2013 and June 2019 in a single institution. In 30 of 50 patients (60%), the procedure was carried out with the patient under local anesthesia and conscious sedation, with the cryoprobe covering the lesion from an extraosseous position, avoiding direct penetration of the nidus. Clinical and radiologic features, procedure-related data, visual analog scale (VAS) pain scores, complications, and overall success rate were evaluated. Statistical analyses were performed by using the nonparametric Friedman test and Wilcoxon signed rank test for repeated measures. Results Fifty patients (median age, 24 years; interquartile range [IQR], 19-38 years; 31 men) underwent CT-guided cryoablation for the treatment of osteoid osteoma, with a 96% (48 of 50 patients) overall clinical success rate. Of the two patients without clinical success, one patient had incomplete pain relief and the other experienced a recurrence of osteoid osteoma at 11 months, which was successfully treated with a second cryoablation procedure. The median VAS pain score was 8 (IQR, 7-8) before the procedure and 0 (IQR, 0-1; P < .001) after the procedure at both primary (6 weeks) and secondary (18-90 months) follow-up. Three of the 50 patients had minor complications (6%); no major complications were reported. Conclusion Osteoid osteoma was safely, effectively, and durably treated with CT-guided percutaneous cryoablation. In the majority of patients, treatment could be performed without general anesthesia, with the cryosphere covering the nidus from an extraosseous position. © RSNA, 2021.

Validation and Optimization of Proximal Femurs Microstructure Analysis Using High Field and Ultra-High Field MRI.

Trabecular bone could be assessed non-invasively using MRI. However, MRI does not yet provide resolutions lower than trabecular thickness and a comparative analysis between different MRI sequences at different field strengths and X-ray microtomography (µCT) is still missing. In this study, we compared bone microstructure parameters and bone mineral density (BMD) computed using various MRI approaches, i.e., turbo spin echo (TSE) and gradient recalled echo (GRE) images used at different magnetic fields, i.e., 7T and 3T. The corresponding parameters computed from µCT images and BMD derived from dual-energy X-ray absorptiometry (DXA) were used as the ground truth. The correlation between morphological parameters, BMD and fracture load assessed by mechanical compression tests was evaluated. Histomorphometric parameters showed a good agreement between 7T TSE and µCT, with 8% error for trabecular thickness with no significative statistical difference and a good intraclass correlation coefficient (ICC > 0.5) for all the extrapolated parameters. No correlation was found between DXA-BMD and all morphological parameters, except for trabecular interconnectivity (R2 > 0.69). Good correlation (p-value < 0.05) was found between failure load and trabecular interconnectivity (R2 > 0.79). These results suggest that MRI could be of interest for bone microstructure assessment. Moreover, the combination of morphological parameters and BMD could provide a more comprehensive view of bone quality.

Survey of MRI Usefulness for the Clinical Assessment of Bone Microstructure.

Bone microarchitecture has been shown to provide useful information regarding the evaluation of skeleton quality with an added value to areal bone mineral density, which can be used for the diagnosis of several bone diseases. Bone mineral density estimated from dual-energy X-ray absorptiometry (DXA) has shown to be a limited tool to identify patients' risk stratification and therapy delivery. Magnetic resonance imaging (MRI) has been proposed as another technique to assess bone quality and fracture risk by evaluating the bone structure and microarchitecture. To date, MRI is the only completely non-invasive and non-ionizing imaging modality that can assess both cortical and trabecular bone in vivo. In this review article, we reported a survey regarding the clinically relevant information MRI could provide for the assessment of the inner trabecular morphology of different bone segments. The last section will be devoted to the upcoming MRI applications (MR spectroscopy and chemical shift encoding MRI, solid state MRI and quantitative susceptibility mapping), which could provide additional biomarkers for the assessment of bone microarchitecture.

Medial meniscal ossicles: Associated knee MRI findings in a multicenter case-control study.

PURPOSE: The purpose of this study was to assess and compare the prevalence of meniscal, ligament and cartilage lesions on knee MRI in a series of age- and sex-matched patients with and without medial meniscal ossicle. MATERIALS AND METHODS: Forty-two knee MRI examinations obtained in 42 patients (36 men, 6 women; mean age, 42.5±22.2 [SD] years; range: 19-65years) on which a medial meniscal ossicle was present were compared to 42 knee MRI examinations obtained in 42 age- and sex-matched patients (36 men, 6 women; mean age, 41.8±20.6 [SD] years; range: 19-65years) on which no medial meniscal ossicles were present. Two radiologists (R1, R2) blinded to the presence of meniscal ossicle by reading only the fat-saturated intermediate-weighted MR images separately assessed the presence of meniscal, ligament and cartilage lesions on these 84 knee MRI examinations. Prevalence of meniscal and ligament lesions and degree of cartilage degradation at MRI were compared between knees with and those without medial meniscal ossicle. RESULTS: In knees with medial meniscal ossicle, R1 and R2 detected 33 (79%) and 38 (90%) medial meniscal lesions, respectively that involved the posterior root (n=25/32 for R1/R2), the posterior horn (n=19/14 for R1/R2) or the body (n=8/10 for R1/R2). The prevalence of posterior root tear (60% [25/42]/76% [32/42] for R1/R2) and that of anterior cruciate ligament (ACL) lesions (48% [20/42]/57% [24/42] for R1/R2) as well as the medial cartilage degradation score (3.35±0.87 [SD] for R1 and 3.92±0.78 [SD] for R2) were significantly greater in knees with than in knees without medial meniscal ossicle (root lesions: P<0.01 for both readers; ACL lesions and medial cartilage score: P<0.01 for both readers). CONCLUSION: On MRI examination, knees with a medial meniscal ossicle demonstrate a greater frequency of medial posterior root tear and of ACL lesions and a greater degree of medial femoro-tibial cartilage degradation by comparison with knees without medial ossicle.