Evaluating blood supply changes in the osteonecrosis of the femoral head using gadobutrol-based steady-state MR angiography.

OBJECTIVES: Assess the feasibility of using gadobutrol-based steady-state (SS) MR angiography (MRA) to evaluate the blood supply changes of osteonecrosis of the femoral head (ONFH). MATERIALS AND METHODS: Participants were recruited in this prospective study from December 2021 to May 2022 in a single center. The number of superior retinacular arteries (SRAs), inferior retinacular arteries (IRAs), anterior retinacular arteries (ARAs), and overall retinacular arteries (ORAs), as well as the affected rates of SRA and IRA, were determined and compared between healthy and ONFH hips and between hips across the Association Research Circulation Osseous (ARCO) staging I-IV. RESULTS: Twenty healthy and 64 ONFH hips were evaluated in 54 participants. There were significant differences between ARCO I-IV for the number of ORAs (mean of 3.5, 2.3, 1.7, and 0.8 for ARCO I-IV, respectively; p < .001), SRAs (median of 2.5, 1, 0.5, and 0 for ARCO I-IV, respectively; p < .001), and the affected rate of SRAs (20.00%, 65.22%, 77.78%, 92.31% for ARCO I-IV, respectively, p = 0.002). There were significant differences between ONFH and healthy hips for the number of ORAs (median of 5 vs. 2; p < .001), SRAs (median of 3 vs. 1; p < .001), IRAs (median of 1 vs. 1; p < .001), ARAs (median of 0 vs. 0; p = 0.04), and also the affected rate of SRAs (5.00% vs. 67.20%, p < .001) and IRAs (30% vs. 84.4%, p < .001). CONCLUSION: Gadobutrol-enhanced SS MRA is a feasible method for evaluation of hemodynamics in ONFH. CLINICAL RELEVANCE STATEMENT: Gadobutrol-enhanced magnetic resonance angiography can evaluate blood supply changes of ONFH and therefore helps to aid in the diagnosis and guide treatment of ONFH. KEY POINTS: • Gadobutrol-enhanced magnetic resonance angiography showed changes in the retinacular artery related to the severity of femoral osteonecrosis. • Gadobutrol-enhanced magnetic resonance angiography revealed a reduced blood supply to the ischemic necrotic femoral head compared to the healthy counterparts.

Evaluating prostate cancer bone metastasis using accelerated whole-body isotropic 3D T1-weighted Dixon MRI with compressed SENSE: a feasibility study.

OBJECTIVES: The study aimed to assess the efficiency of whole-body high-resolution compressed sensing-sensitivity encoding isotropic T1-Weighted Dixon (CSI-T1W-Dixon) scans in evaluating bone metastasis. METHODS: Forty-five high-risk prostate cancer patients with bone metastases were enrolled prospectively and underwent whole-body MRI sequences, which included the following: pre- and post-contrast CSI-T1W-Dixon and conventional multi-planar T1-Weighted Dixon (CMP-T1W-Dixon) (coronal, sagittal, and axial scans), short tau inversion recovery (STIR), and DWI. Comparison between the CMP-T1W-Dixon and CSI-T1W-Dixon images was done for the subjective image quality, the quantitative contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). Furthermore, the diagnostic performance based on per-lesion and per-patient basis utilizing non-contrast T1-weighted (T1)/T1+ contrasted T1-weighted (T1C)/T1 + T1C + STIR + DWI sequences was compared between the CSI-T1W-Dixon and CMP-T1W-Dixon methods using reference standards (combining biopsy data and 6-month imaging follow-up). RESULT: The CSI-T1W-Dixon images produced fewer image artifacts in the axial and coronal planes compared to the CMP-T1W-Dixon images. Also, the CSI-T1W-Dixon images provided better a CNR in fat-only images of all three planes and water-only images of the axial plane (p < 0.05). The CSI-T1W-Dixon showed a higher sensitivity than the CMP-T1W-Dixon techniques in analyzing T1-only images on a per-lesion basis (82.7% vs. 53.8% for sensitivity, p = 0.03). On a per-patient basis, no difference was found in the diagnostic capacity between the CSI-T1W-Dixon and CMP-T1W-Dixon sequences either alone or in combinations (p = 0.57-1). CONCLUSION: High-resolution CSI-T1W-Dixon with higher image quality and diagnostic capacity can replace the CMP-T1W-Dixon method in evaluating bone metastasis in clinical practice. KEY POINTS: • Compressed sensing isotropic acquisition for 3D T1-weighted Dixon images can improve the image quality with fewer artifacts compared to the anisotropic multiplanar acquisition. • Compressed sensing isotropic acquisition can save 67% of scanning time compared to anisotropic multiplanar acquisition. • Compressed sensing isotropic 3D T1-weighted Dixon images can offer better diagnostic performance with higher sensitivity compared to anisotropic multiplanar images.

Medical cooperative authenticated key agreement schemes with involvement of personal care assistant in telemedicine.

BACKGROUND AND OBJECTIVE: Due to the mature development of information and network technology, telemedicine is increasingly able to facilitate the implementation of long-term care for patients with disabilities. Such patients may, however, not be adept at usage of such technological products, thus personal care assistants (PCAs) are required to assist in such usage. While PCAs collaborate with patients in operating telehealth systems, such use also poses challenges to security and raises concerns involving the authenticity of all the related participants. Even mutual authentication between patients and physicians can be a challenge when patients change or have multiple physicians, which raises key management concerns. METHODS: A cooperative authenticated key agreement scheme is developed to address the various security scenarios when providing telemedicine care to patients with a disability. In addition, an enhanced version scheme with group key exchange functionality is proposed to satisfy situations where more than one physician is involved in providing services during a medical consultation situation. RESULTS: The proposed schemes achieve the scenarios of PCAs involvement and group consultation in telemedicine with perfect security properties including mutual authentication, session key agreement, forward secrecy, known-key security, impersonation attack prevention, replay attack prevention, and insider attack prevention. The performance analysis is demonstrated to show the feasibility of our schemes. CONCLUSIONS: Two schemes are presented for a patient with a disability in a telemedicine scenario. The first scheme establishes a solution for a typical situation where the patient and a personal care assistant cooperatively log into the telemedicine system and achieve a key agreement with the designated physician. Considering the case of multiple physicians' collaboration, the second scheme provides a solution by forming a group for the patient and physicians and then distributes a group key between the group members to set up a secure communication platform.

Improving the accuracy of pre-operative evaluation of neurovascular conflict in trigeminal neuralgia using magnetic resonance subtraction.

PURPOSE: To investigate the ability of magnetic resonance (MR) subtraction to evaluate neurovascular conflict (NVC) and to compare it with conventional MR protocols. METHODS: This prospective study included 82 patients with trigeminal neuralgia who underwent microvascular decompression for NVC. All patients had a pre-operative examination using 3T MRI. The MRI protocols used comprised 3D balanced (B)-fast field echo (FFE), 3D steady-state magnetic resonance angiography (MRA), and 3D T1-FFE sequences. MR subtraction images were obtained by subtracting native images from B-FFE and steady-state MRA. NVC evaluation was performed using subtraction images (MR subtraction) and combination images (conventional MR protocols using B-FFE and T1-FFE in combination). Clinical assessment of the degree of compression, the type of compressing vessel, and the location of conflict were undertaken by two independent observers. The two methods were then compared using surgical criteria. RESULTS: MR subtraction exhibited greater accuracy than the conventional method in terms of the estimated severity of conflict (87.80% vs. 57.32%, p < 0.05), and demonstrated better consistency with surgical findings (k = 0.794 vs. k = 0.365, p < 0.05). For the type of compressing vessel and the location of conflict, both methods were highly accurate and agreed to a similar extent with surgical findings (p = 0.987, compressing vessel; p = 0.665, location of conflict). CONCLUSION: MR subtraction proved reliable in NVC pre-operative evaluation, with increased accuracy when estimating severity. This result strongly supports the wider use of MR subtraction as the preferred choice in clinical application.

Detection of vascularity of femoral head using sub-millimeter resolution steady-state magnetic resonance angiography-initial experience.

OBJECTIVE: The purpose of this study was to use the steady-state (SS) magnetic resonance angiography (MRA) with a sub-millimeter resolution to detect the arteries supplying to the femoral head (FH). MATERIALS AND METHOD: SS MRA scanning of hips was performed bilaterally in 15 healthy volunteers. A blood pool contrast agent was used. The scanning protocol included a 0.8-mm3 isotropic T1-fast field echo sequence with spectral fat suppression technique. Two highly qualified radiologists independently evaluated the medial circumflex femoral artery (MCFA), the lateral circumflex femoral artery (LCFA), and the three retinacular arteries including superior retinacular artery (SRA), inferior retinacular artery (IRA), and anterior retinacular artery (ARA). The intraosseous branches of the three retinacular arteries were also evaluated. An orthopaedic surgeon was consulted in case of disagreement. Observation by the two radiologists and support from the orthopaedic surgeon served as the end result. Agreement between the two observer radiologists was evaluated. RESULTS: Interobserver agreement between the two radiologists was found to be substantial to perfect. Of the 30 hips, the LCFA and MCFA were detected in all hips; the SRA and IRA were detected in most hips (100%, 90%), and the ARA was detected in 13 hips (43%). The intraosseous branches of SRA and IRA were detected in 30 and 22 hips (100%, 73%), respectively, while the intraosseous branches of ARA were detected in 11 hips (37%). CONCLUSION: The main arteries supplying the FH can be detected by the SS MRA, making it a novel method to detect the vascularity of FH.