Radiation dose reduction and image quality improvement with ultra-high resolution temporal bone CT using deep learning-based reconstruction: An anatomical study.

PURPOSE: The purpose of this study was to evaluate the achievable radiation dose reduction of an ultra-high resolution computed tomography (UHR-CT) scanner using deep learning reconstruction (DLR) while maintaining temporal bone image quality equal to or better than high-resolution CT (HR-CT). MATERIALS AND METHODS: UHR-CT acquisitions were performed with variable tube voltages and currents at eight different dose levels (volumic CT dose index [CTDIvol] range: 4.6-79 mGy), 10242 matrix, and 0.25 mm slice thickness and reconstructed using DLR and hybrid iterative reconstruction (HIR) algorithms. HR-CT images were acquired using a standard protocol (120 kV/220 mAs; CTDI vol, 54.2 mGy, 5122 matrix, and 0.5 mm slice thickness). Two radiologists rated the image quality of seven structures using a five point confidence scale on six cadaveric temporal bone CTs. A global image quality score was obtained for each CT protocol by summing the image quality scores of all structures. RESULTS: With DLR, UHR-CT at 120 kV/220 mAs (CTDIvol, 50.9 mGy) and 140 kV/220 mAs (CTDIvol, 79 mGy) received the highest global image quality scores (4.88 ± 0.32 [standard deviation (SD)] [range: 4-5] and 4.85 ± 0.35 [range: 4-5], respectively; P = 0.31), while HR-CT at 120 kV/220 mAs and UHR-CT at 120 kV/20 mAs received the lowest (i.e., 3.14 ± 0.75 [SD] [range: 2-5] and 2.97 ± 0.86 [SD] [range: 1-5], respectively; P = 0.14). All the DLR protocols had better image quality scores than HR-CT with HIR. CONCLUSION: UHR-CT with DLR can be performed with up to a tenfold reduction in radiation dose compared to HR-CT with HIR while maintaining or improving image quality.

MR imaging signs of shoulder adhesive capsulitis: analysis of potential differentials and improved diagnostic criteria.

OBJECTIVE: To evaluate the prevalence of shoulder adhesive capsulitis (AC) signs on MR studies of patients with various common shoulder conditions. METHODS: MR images of 316 patients were retrospectively evaluated. Patients were divided into three groups: controls (66 patients), clinical AC (63 patients), and study group (187 patients). The final diagnosis of AC was reached clinically. The study group was composed of patients with focal and massive rotator cuff tears, active hydroxyapatite deposition disease, fractures around the shoulder, and post-surgery. The following AC signs were evaluated: inferior glenohumeral ligament (IGHL) thickening; coracohumeral ligament (CHL) thickening; and hyperintensity of the inferior glenohumeral ligament, which was graded in four classes. RESULTS: The IGHL signal intensity was statistically higher in patients with fractures than in controls (P = 0.008). There was no statistically significant difference in IGHL signal between the AC group and patients with massive rotator cuff tears and active hydroxyapatite deposition disease (P > 0.1). IGHL thickness in patients with fractures, massive rotator ruptures, and active hydroxyapatite deposition disease was significantly higher compared to controls (P < 0.02) and significantly lower compared to the AC group (P < 0.0001). Based on these findings, a grading system for fibro-inflammatory capsular changes is proposed. CONCLUSION: MR AC signs are frequent in patients with shoulder conditions other than AC; however, in these patients, capsular changes are less prominent than in patients with clinical AC.

Measurement of stapes footplate thickness using ultra-high-resolution computed tomography: stapes axial plane correlates better with otosclerosis than lateral semicircular canal plane.

BACKGROUND, AIMS: Stapes footplate thickness measurement using ultra-high-resolution CT has been described only in the lateral semicircular canal plane. The purpose of this study was to compare stapes footplate thickness between the lateral semicircular canal and stapes axial planes in patients with otosclerosis compared to controls. MATERIAL AND METHODS: We performed a retrospective single-center study of patients undergoing high-resolution temporal bone CT. Two radiologists measured stapes footplate thickness in both the lateral semicircular canal and stapes axial planes. RESULTS: Between February 2020 and October 2022, we collected 81 ears from 49 patients (75% of women; mean age 51.22 ± 16.6 years, 17 otosclerosis, and 64 controls). In the stapes axial plane, there was a significant anterior thickening in otosclerosis patients (Reader 1: 0.52 ± 0.12 [0.3-0.7] vs. 0.41 ± 0.08 [0.3-0.6], p = 0.001; Reader 2: 0.54 ± 0.06 [0.5-0.7] vs. 0.39 ± 0.08 [0.2-0.6], P < 0.001) compared to controls. These differences were not significant using the lateral semicircular canal plane. CONCLUSION: The stapes footplate was thickened at its AC in otosclerosis patients using only the stapes axial plane. SIGNIFICANCE: We propose to use the stapes axial plane instead of the lateral semicircular canal plane when analyzing the stapes.

Ultra-high-resolution CT of the temporal bone: The end of stapes prosthesis dimensional error and correlation with patient symptoms.

PURPOSE: To describe the reliability of ultra-high-resolution computed tomography (UHR-CT) in the measurement of titanium stapes prostheses using manufacturer data as a reference. MATERIALS AND METHODS: This retrospective study included patients treated by stapedectomy with titanium prostheses who underwent UHR-CT between January 2020 and October 2023. Images were acquired using an ultra-high-resolution mode (slice thickness: 0.25 mm; matrix, 1024 × 1024). Two radiologists independently evaluated the length, diameter, and intra-vestibular protrusion of the prosthesis. Post-operative air-bone gaps (ABGs) were recorded. RESULTS: Fourteen patients were enrolled (mean age, 44.3 ± 13.8 [SD] years, 9 females), resulting in 16 temporal bone UHR-CTs. The exact length was obtained in 81.3 % (n = 13/16) and underestimated by 0.1 to 0.3 mm in the remaining 18.7 % (n = 3/16) CT scans for both readers (mean misestimation: -0.02 ± 0.06 [SD] mm, overall underestimation of 0.43 %). The exact diameter was reported in 75 % (n = 12/16) and 87.5 % (n = 14/16) of the CT scans for readers 1 and 2, respectively, and was off by 0.1 mm in all discrepancies (mean misestimation: 0.01 ± 0.04 [SD] mm, overall overestimation of 2.43 %). Intravestibular prosthesis protrusion was of 0.5 ± 0.43 [SD] mm (range: 0-1) and 0.49 ± 0.44 [SD] mm (range: 0-1.1) for readers 1 and 2, respectively, and did not correlate with ABGs (r = 0.25 and 0.22; P = 0.39 and 0.47 for readers 1 and 2, respectively). Intra and interobserver agreements were excellent. CONCLUSION: UHR-CT provides 99.6 % and 97.6 % accuracy for prosthesis length and diameter measurements, respectively.

Quantitative and qualitative evaluation of three MSCT for high resolution bone imaging.

INTRODUCTION: Strategies for achieving high resolution varies between manufacturers. In CT, the helical mode with narrow collimation has long been considered as the gold standard for high-resolution imaging. More recently, incremental modes with small dexels and focal spot, have been developed but have not been compared with helical acquisitions under optimal conditions. The aim of this work is to compare the high-resolution acquisition strategies currently proposed by recent MSCT. METHODS: Three CT systems were compared. A phantom was used to evaluate geometric accuracy, uniformity, scan slice geometry, and spatial resolution. Human dry bones were used to test different protocols on real bone architecture. A blind visual analysis was conducted by trained CT users for classifying the different acquisitions (p-values). RESULTS: All systems give satisfactory results in terms of geometric accuracy and uniformity. The in-plane MTF at 5% were respectively 13.4, 15.9 and 18.1 lp/cm. Dry-bones evaluation confirms that acquisition#3 is considered as the best. CONCLUSIONS: The incremental acquisition coupled with à small focal spot, and a high-sampling detector, overpasses the reference of low-pitch helical acquisitions for high-resolution imaging. Cortical bone, bony vessels, and tumoral matrix analysis are the very next challenges that will have to be managed to improve normal and pathologic bone imaging thanks to the availability UHR-CT systems.

Ultra-high-resolution CT of the temporal bone: Comparison between deep learning reconstruction and hybrid and model-based iterative reconstruction.

PURPOSE: The purpose of this study was to evaluate the ability of ultra-high-resolution computed tomography (UHR-CT) to assess stapes and chorda tympani nerve anatomy using a deep learning (DLR), a model-based, and a hybrid iterative reconstruction algorithm compared to simulated conventional CT. MATERIALS AND METHODS: CT acquisitions were performed with a Mercury 4.0 phantom. Images were acquired with a 1024 × 1024 matrix and a 0.25 mm slice thickness and reconstructed using DLR, model-based, and hybrid iterative reconstruction algorithms. To simulate conventional CT, images were also reconstructed with a 512 × 512 matrix and a 0.5 mm slice thickness. Spatial resolution, noise power spectrum, and objective high-contrast detectability were compared. Three radiologists evaluated the clinical acceptability of these algorithms by assessing the thickness and image quality of the stapes footplate and superstructure elements, as well as the image quality of the chorda tympani nerve bony and tympanic segments using a 5-point confidence scale on 13 temporal bone CT examinations reconstructed with the four algorithms. RESULTS: UHR-CT provided higher spatial resolution than simulated conventional CT at the penalty of higher noise. DLR and model-based iterative reconstruction provided better noise reduction than hybrid iterative reconstruction, and DLR had the highest detectability index, regardless of the dose level. All stapedial structure thicknesses were thinner using UHR-CT by comparison with conventional simulated CT (P < 0.009). DLR showed the best visualization scores compared to the other reconstruction algorithms (P < 0.032). CONCLUSION: UHR-CT with DLR results in less noise than UHR-CT with hybrid iterative reconstruction and significantly improves stapes and tympanic chorda tympani nerve depiction compared to simulated conventional CT and UHR-CT with iterative reconstruction.

Olfactory cleft stenosis and obstruction on paranasal sinus CT scan in pre-septo-rhinoplasty patients: normal variants or pathologic findings?

OBJECTIVE(S): To determine the frequency of olfactory cleft (OC) stenosis and obstruction on paranasal sinus CT scans in pre-septorhinoplasty of patients who had septal deviation, septopyramidal deformation or nasal obstruction without other sinonasal conditions. METHODS: This retrospective study included patients referred to our institution between December 2013 and December 2021 for septorhinoplasty due to nasal obstruction without other sinonasal or neurological conditions. All patients underwent preoperative paranasal sinus CT scan and olfactory testing. OC stenosis was quoted as none, partial, or total (less than 1/3 contact between nasal septum and ethmoid turbinates, 1/3-2/3, more than 2/3, respectively), as well as OC obstruction as none, partial, or complete (obstruction of less than 1/3 of OC, 1/3-2/3, more than 2/3, respectively). Radiologic evaluation was validated by near perfect interobserver agreement. RESULTS: A total of 75 patients (32 women, 43 men) with a mean age of 44.2 ± 15.64 (23-74) years were included, of which 36 were normosmic and 39 hyposmic. OC stenosis was partial in 58.7% (n = 44) of the patients, absent in 28% (n = 21), and total in 13.3% (n = 10), without difference between normosmic and hyposmic patients (p = .66). OC obstruction was absent in 52% (n = 39) and partial in 46.7% (n = 35), without difference between normosmic and hyposmic patients (p = .51). Only one normosmic patient had complete OC obstruction. CONCLUSION: OC partial stenosis and partial obstruction were frequent findings in pre-septorhinoplasty patients without respiratory mucosa disease and did not influence their olfactory status. Total stenosis and complete obstruction were rarer and require further investigation. CLINICAL RELEVANCE STATEMENT: Isolated partial olfactory cleft stenosis and obstruction should be considered normal variants, whereas the impact of complete olfactory cleft stenosis and obstruction on patient's olfactory status remains to be determined. KEY POINTS: • The incidence of olfactory cleft stenosis and obstruction in asymptomatic patients remains unknown, even though it is encountered in clinical practice. • Partial and total olfactory cleft stenosis occurred in 58.7% and 13.3% of the patients; partial obstruction occurred in half of the cases, but complete obstruction was extremely rare. • There are frequent findings of partial olfactory cleft obstruction and stenosis, but complete obstruction and total stenosis should be further investigated.

In vivo depiction of cortical bone vascularization with ultra-high resolution-CT and deep learning algorithm reconstruction using osteoid osteoma as a model.

PURPOSE: The purpose of this study was to evaluate the ability to depict in vivo bone vascularization using ultra-high-resolution (UHR) computed tomography (CT) with deep learning reconstruction (DLR) and hybrid iterative reconstruction algorithm, compared to simulated conventional CT, using osteoid osteoma as a model. MATERIALS AND METHODS: Patients with histopathologically proven cortical osteoid osteoma who underwent UHR-CT between October 2019 and October 2022 were retrospectively included. Images were acquired with a 1024 × 1024 matrix and reconstructed with DLR and hybrid iterative reconstruction algorithm. To simulate conventional CT, images with a 512 × 512 matrix were also reconstructed. Two radiologists (R1, R2) independently evaluated the number of blood vessels entering the nidus and crossing the bone cortex, as well as vessel identification and image quality with a 5-point scale. Standard deviation (SD) of attenuation in the adjacent muscle and that of air were used as image noise and recorded. RESULTS: Thirteen patients with 13 osteoid osteomas were included. There were 11 men and two women with a mean age of 21.8 ± 9.1 (SD) years. For both readers, UHR-CT with DLR depicted more nidus vessels (11.5 ± 4.3 [SD] (R1) and 11.9 ± 4.6 [SD] (R2)) and cortical vessels (4 ± 3.8 [SD] and 4.3 ± 4.1 [SD], respectively) than UHR-CT with hybrid iterative reconstruction (10.5 ± 4.3 [SD] and 10.4 ± 4.6 [SD], and 4.1 ± 3.8 [SD] and 4.3 ± 3.8 [SD], respectively) and simulated conventional CT (5.3 ± 2.2 [SD] and 6.4 ± 2.5 [SD], 2 ± 1.2 [SD] and 2.4 ± 1.6 [SD], respectively) (P < 0.05). UHR-CT with DLR provided less image noise than simulated conventional CT and UHR-CT with hybrid iterative reconstruction (P < 0.05). UHR-CT with DLR received the greatest score and simulated conventional CT the lowest score for vessel identification and image quality. CONCLUSION: UHR-CT with DLR shows less noise than UHR-CT with hybrid iterative reconstruction and significantly improves cortical bone vascularization depiction compared to simulated conventional CT.

Low-Dose Remifentanil in Preterm Cesarean Section with General Anesthesia: A Randomized Controlled Trial.

BACKGROUND AND OBJECTIVE: The conventional technique of general anesthesia induction during a Cesarean section involves the use of opioids only after cord clamping. We hypothesized that the use of remifentanil before cord clamping might reduce the use of maternal supplemental anesthetic agents and improve the maternal hemodynamics status and neonatal adaptation of the preterm neonate. METHODS: A phase III, double-blind, randomized, placebo-controlled, hospital-based trial enrolled parturients undergoing a Cesarean section under general anesthesia before 37 weeks of gestation. Block randomization allocated pregnant women to remifentanil or placebo. The primary outcome was the rate of newborns with Apgar scores < 7 at 5 min. Secondary outcomes were maternal hemodynamic parameters, complications of anesthetic induction, use of adjuvant anesthetic agents, neonatal respiratory distress, umbilical cord pH, and lactate levels. RESULTS: A total of 52/55 participants were analyzed, comprising 27 women in the remifentanil group and 25 in the placebo group. Nine of 27 (33.3%) neonates had an Apgar score < 7 at 5 min in the remifentanil group versus 11/25 (44.0%) in the placebo group (p = 0.45, odds ratio = 0.66, 95 confidence interval 0.20-2.18). The blood cord gases, cognitive, behavior, sensory, sleeping, and feeding scores at 1 and 2 years of corrected age were not different. For the mothers, hemodynamic parameters, anesthesia duration, and the cumulative treatment dose until cord clamping did not differ between the groups. CONCLUSIONS: The use of a low dose of remifentanil before cord clamping for a Cesarean section appears to be safe both for the mother and the preterm newborn, but it does not improve maternal or neonatal outcomes. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: NCT02029898.

Computed Tomography Bone Imaging: Pushing the Boundaries in Clinical Practice.

Bone microarchitecture has several clinical implications over and above estimating bone strength. Computed tomography (CT) analysis mainly uses high-resolution peripheral quantitative CT and micro-CT, research imaging techniques, most often limited to peripheral skeleton assessment. Ultra-high-resolution (UHR) CT and photon-counting detector CT, two commercially available techniques, provide images that can approach the spatial resolution of the trabeculae, bringing bone microarchitecture analysis into clinical practice and improving depiction of bone vascularization, tumor matrix, and cortical and periosteal bone. This review presents bone microarchitecture anatomy, principles of analysis, reference measurements, and an update on the performance and potential clinical applications of these new CT techniques. We also share our clinical experience and technical considerations using an UHR-CT device.

Initial Evaluation of Focal Bone Lesions: How Do We Do It?

Focal bone lesions are frequent, and management greatly depends on the characteristics of their images. After briefly discussing the required work-up, we analyze the most relevant imaging signs for assessing potential aggressiveness. We also describe the imaging aspects of the various types of lesion matrices and their clinical implications.

Assessment of Scapholunate Instability on 4D CT Scans in Patients with Inconclusive Conventional Images.

Background Initial imaging work-up using radiography and CT arthrography sometimes can be insufficient to identify a scapholunate (SL) instability (SLI) in patients suspected of having SL ligament tears. Purpose To determine the diagnostic performance of four-dimensional (4D) CT in the identification of SLI and apply the findings to patients suspected of having SLI and with inconclusive findings on radiographs and CT arthrograms. Materials and Methods This prospective single-center study enrolled participants suspected of having SLI (recent trauma, dorsal pain, positive Watson test results, decreased grip strength) between March 2015 and March 2020. Participants with wrist fractures, substantial joint stiffness, or history of wrist surgery were excluded. Each participant underwent radiography, CT arthrography, and 4D CT on the same day. Participants were divided into three groups: those with no SLI, those with SLI, and those with inconclusive results. SL gap and radioscaphoid and lunocapitate angle were measured using semiautomatic quantitative analysis of 4D CT images by two independent readers. Receiver operating characteristic curves were used to evaluate the diagnostic performance of 4D CT. Thresholds were determined with the Youden index and were applied to the inconclusive group. Results Of the 150 included participants (mean age, 41 years ± 14 [SD]; 102 male, 48 female), there were 63 with no SLI, 48 with SLI, and 39 with inconclusive results. The maximum value and range of SL gap measurements on 4D CT scans showed high sensitivity (83% [40 of 48] and 90% [43 of 48], respectively) and high specificity (95% [59 of 62] and 81% [50 of 62], respectively) in the identification of SLI. At least one of these parameters was abnormal on 4D CT scans in 17 of 39 (44%) participants in the inconclusive group, and 10 of 17 (59%) participants had confirmed SLI. In the 22 participants in the inconclusive group with no indication of SLI at 4D CT, follow-up showed no evidence of SLI in 10 (45%) and enabled confirmation of SLI via arthroscopy in three (14%). Conclusion Scapholunate gap measurements on kinematic 4D CT scans enabled correct identification of SLI in 59% of participants with inconclusive results on conventional images. ClinicalTrials.gov registration no. NCT02401568 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Demehri and Ibad in this issue.

Methodology for quantitative evaluation of mandibular condyles motion symmetricity from real-time MRI in the axial plane.

Diagnosis of temporomandibular disorders is currently based on clinical examination and static MRI. Real-time MRI enables tracking of condylar motion and, thus, evaluation of their motion symmetricity (which could be associated with temporomandibular joint disorders). The purpose of this work is to propose an acquisition protocol, an image processing approach, and a set of parameters enabling objective assessment of motion asymmetry; to check the reliability and find the limitations of the approach, and to verify if the automatically calculated parameters are associated with the motion symmetricity. A rapid radial FLASH sequence was used to acquire a dynamic set of axial images for 10 subjects. One more subject was involved to estimate the dependence of the motion parameters on the slice placement. The images were segmented with a semi-automatic approach based on U-Net convolutional neural network, and the condyles' mass centers were projected on the mid-sagittal axis. Resulting projection curves were used for the extraction of various motion parameters including latency, velocity peak delay, and maximal displacement between the right and the left condyle. These automatically calculated parameters were compared with the physicians' scores. The proposed segmentation approach allowed a reliable center of mass tracking. Latency and velocity peak delay were found to be invariant to the slice position, and maximal displacement difference considerably varied. The automatically calculated parameters demonstrated a significant correlation with the experts' scores. The proposed acquisition and data processing protocol enables the automatizable extraction of quantitative parameters that characterize the symmetricity of condylar motion.

Zero echo time MRI in shoulder MRI protocols for the diagnosis of rotator cuff calcific tendinopathy improves identification of calcific deposits compared to conventional MR sequences but remains sub-optimal compared to radiographs.

OBJECTIVE: To compare the diagnostic performance of standard MRI and standard MRI + ZTE images for the detection of rotator cuff calcific tendinopathy (RCCT) and to describe the artifacts encountered with ZTE images, using computed radiography (CR) as a reference. METHODS: In a retrospective study, patients with suspicion of rotator cuff tendinopathy who underwent standard MRI + ZTE images after radiography were enrolled between June 2021 and June 2022. Images were independently analyzed for calcific deposit presence and ZTE images artifacts, by two radiologists. Diagnostic performance was calculated individually with MRI + CR as the reference standard. RESULTS: A total of 46 RCCT subjects (27 women; mean age, 55.3 years ± 12.4) and 51 control subjects (27 men; mean age, 45.5 ± 12.9) were evaluated. For both readers, there was an increase in the sensitivity for the identification of calcific deposits of MRI + ZTE compared to MRI (77% (95% CI: 64.5-86.8) and 75.4% (95% CI: 62.7-85.5) versus 57.4% (95% IC: 44.1-70) and 47.5% (95% IC: 34.6-60.7), for R1 and R2, respectively). Specificity was quite similar for both readers and both imaging techniques and ranged from 96.6% (95% IC: 93.3-98.5) to 98.7% (95% IC: 96.3-99.7). Hyperintense joint fluid (62.8% of patients), long head of the biceps tendon (in 60.8%), and subacromial bursa (in 27.8%) on ZTE were considered artifactual. CONCLUSION: The addition of ZTE images to a standard MRI protocol improved MRI diagnostic performance of RCCT, but with a suboptimal detection rate and a relatively high frequency of artifactual soft tissue signal hyperintensity. KEY POINTS: • Adding ZTE images to standard shoulder MRI improves the MR-based detection of rotator cuff calcific tendinopathy, but half of the calcification unseen with standard MRI remained unseen with ZTE MRI. On ZTE images, joint fluid and long head biceps tendon were hyperintense in about 60% of the shoulders, as well as the subacromial bursa in about 30%, without calcific deposit on conventional radiographs. • The detection rate of calcific deposits using ZTE images was dependent on the disease phase. In the calcific stage, it reached 100% in this study but remained at a maximum of 80.7% in the resorptive phase.

Radiological evolution of progestogen-induced meningioma: A monocentric retrospective study.

Cyproterone acetate (CPA) is known to induce meningioma, and recently, nomegestrol acetate (NMA) and chlormadinone acetate (CMA) were also involved. Progestagen-induced meningioma management starts with progestogen discontinuation and is either interventional (surgery and/or radiotherapy) or conservative (clinical and MRI radiological follow-up). We performed a retrospective volumetric radiological outcomSe study of progestogen-induced meningiomas diagnosed in our hospital. We analysed progestogen-related meningiomas diagnosed until 30 June 2021, with at least one diagnostic and one follow-up MRI results. Meningioma volumes were centrally retrospectively measured using a T1-weighted 3D millimeter sequence with gadolinium injection on a postprocessing console. We analysed 98 meningiomas of 38 females and one transgender (male-to-female), of which 25 (64.1%) had taken CPA, seven (17.9%) NMA, three (7.7%) CMA, and four (10.2%) several progestogens. Eleven patients (24 meningiomas) underwent interventional management, seven patients had meningiomas followed by conservative or interventional management, and 21 patients (51 meningiomas) had only conservative management. Of these 21 patients, 17 had discontinued their progestogen less than 6 months before, of which 14 (82.3%) had decreased or stable meningioma(s) during a 24-month median follow-up (3 to 75) period. Overall, four of the 39 patients experienced meningioma progression (three during conservative treatment and one after surgery), including two patients who had continued NMA or CMA treatment several years after diagnosis. Our study confirms a generally favourable outcome of progestogen-related meningioma after conservative treatment, especially for CPA. It also underlines the need for progestogen discontinuation at meningioma diagnosis.

Quantitative dynamic contrast-enhanced MRI of bone marrow perfusion at the proximal femur: influence of femoral head osteonecrosis risk factor and overt osteonecrosis.

OBJECTIVE: To evaluate the MRI perfusion changes in patients with risk factors for osteonecrosis and normally appearing femoral heads prior to overt femoral head osteonecrosis. METHODS: Fifty-eight patients (105 hips) were prospectively included in this ethics committee-approved study. There were 46 hips with no image anomalies and no risk factors for osteonecrosis of the femoral head (ONFH) risk factors, 38 with ONFH risk factors and no image abnormalities, and 21 with overt ONFH. All patients underwent DCE-MRI. Semi-quantitative (peak enhancement [PE], area under the curve [AUC], time to maximum enhancement [TME]) and quantitative perfusion parameters (volume plasma, KTRANS, and KEP) were calculated. Excessive alcohol consumption, corticosteroid use, and trauma were considered major risk factors for osteonecrosis of the femoral head. RESULTS: Measured at the femoral neck and compared to the healthy hips without OFNH risk factors, PE was significantly lower in the hips of patients with OFNH risk factors. Moreover, the difference was greater in females with risk factors, who presented significantly lower PE values (p = 0.0096). A PE threshold of 1.4% yielded a 92% sensitivity and 54% specificity for the presence of associated ONFH risk factors. The hips with overt OFNH compared to those with normally appearing showed an increase of PE of 45% in the neck (p < 0.014). Various epiphyseal femoral head perfusion parameters (PE, TME, AUC, and Ktrans) presented statistically significant differences in hips with ONFH and those without (p < 0.0001). CONCLUSION: DCE-MRI can identify perfusion marrow changes related to the presence of ONFH risk factors and adjacent to osteonecrosis areas. KEY POINTS: • Bone marrow perfusion changes may occur prior to overt ONFH and extend beyond the osteonecrosis area to the entire femoral head and neck. • Peak enhancement values were significantly reduced in patients with ONFH risk factors, compared to those without. • The presence of ONFH led to a significant increase in marrow perfusion adjacent to the osteonecrosis area.

Association between opportunistic vertebral bone density measurements and new vertebral fractures after percutaneous vertebral cementoplasty: a case-control study.

OBJECTIVES: To study the relationship between opportunistic CT bone density measurements and the occurrence of new vertebral fractures after percutaneous vertebral cementoplasty (PVC) of osteoporotic vertebral compression fractures (OVCF). METHODS: A prospective analysis of retrospective data of 275 patients with OVCF treated by PVC between 2014 and 2019 with a clinico-radiological follow-up one year after treatment was conducted. Opportunistic bone density measurements were obtained at the trabecular bone of the L1 or an adjacent vertebra in Hounsfield units performed on the preoperative CT study. These density measurements values ​​were then compared between patients with and without new OCVF and in various population subgroups. RESULTS: There were 275 patients included, with 53 (19%) presenting a new OCVF and 24 (9%) developing a fracture cascade. The median opportunistic density measurements ​​in patients with recurrent OCVF were lower than those without (median 52[40.5]) HU and 77[49] HU)(p < 0.00001). Among the patients with new OVCF the median opportunistic density measurements in patients with fracture cascades were also lower than those without (44 HU and 62 HU, respectively) (p < 0.0096). Patients with density measurements under 61 HU were 3.6 times more likely to present recurrent fractures and those with density under 54 HU were 9.8 times more likely to develop a fracture cascade. The 36 HU threshold yielded a high specificity (90-91%) for the prediction of recurrent fractures and fracture cascade but with low sensitivity (respectively 26% and 37%). CONCLUSION: Low opportunistic vertebral density measurements are associated with a higher risk of OVCF and fracture cascades after PVC. KEY POINTS: • Low opportunistic density measurements are associated with a higher risk of OVCF and fracture cascades after PVC. • Measuring bone density before performing a PVC could help predict the risk of new vertebral fracture after treatment • Patient management could be adapted according to bone density.

Initial Characterization of Focal Bone Lesions with Conventional Radiographs or Computed Tomography: Diagnostic Performance and Interobserver Agreement Assessment.

Objectives: To ascertain the role of CT and conventional radiographs for the initial characterization of focal bone lesions.Methods: Images from 184 patients with confirmed bone tumors included in an ethics committee-approved study were retrospectively evaluated. The reference for benign-malignant distribution was based on histological analysis and long-term follow-up. Radiographs and CT features were analyzed by 2 independent musculoskeletal radiologists blinded to the final diagnosis. Lesion margins, periosteal reaction, cortical lysis, endosteal scalloping, presence of pathologic fracture, and lesion mineralization were evaluated. Results: The benign-malignant distribution in the study population was 68.5-31.5% (126 benign and 58 malignant). In the lesions that could be seen in both radiographs and CT, the performance of these methods for the benign-malignant differentiation was similar (accuracy varying from 72.8% to 76.5%). The interobserver agreement for the overall evaluation of lesion aggressiveness was considerably increased on CT compared to radiographs (Kappa of .63 vs .22). With conventional radiographs, 18 (9.7%) and 20 (10.8%) of the lesions evaluated were not seen respectively by readers 1 and 2. Among these unseen lesions, 50%-61.1% were located in the axial skeleton. Compared to radiographs, the number of lesions with cortical lysis and endosteal scalloping was 26-34% higher with CT. Conclusion: Although radiographs remain the primary imaging tool for lesions in the peripheral skeleton, CT should be performed for axial lesions. CT imaging can assess the extent of perilesional bone lysis more precisely than radiographs with a better evaluation of lesion fracture risk.

Anatomy of the nasal latero-lateral cartilage articulation: a micro-MRI study in human specimens.

PURPOSE: To study the anatomy of the latero-lateral joint (LLJ) between the upper lateral (ULC) and lower lateral (LLC) crus of the nasal cartilages, usually described as a scroll articulation. METHODOLOGY: Six nasal pyramids were taken in monobloc from fresh cadavers and imaged on micro-MRI with 0.4 mm slice thickness. Images were jointly interpreted by two head and neck radiologists and one surgeon. The junction between the ULC and LLC, the presence of ligaments and of sesamoid or accessory cartilages were assessed. RESULTS: Eight LLJs could be analyzed, with four types of junctions: hook-shaped cephalic border of the LLC turned towards the nasal fossa and linear caudal border of the ULC (n = 3), hook-shaped caudal border of the ULC and linear cephalic border of the LLC lateral crus (n = 1), hook-shaped border of both cartilaginous edges with clinging (n = 1) (scroll articulation) or without clinging (n = 3). No ligament or sesamoid cartilage was found, but posterior accessory cartilages were seen in 75% of the cases. CONCLUSION: The classical scroll articulation of the LLJ has been observed in only 1/8 cases on micro-MRI images. The anatomy of the LLJ could explain the surgical difficulty in raising the tip of the nose in some patients and not in others.