Topics in Magnetic Resonance Imaging最新文献

Abstract: Magnetic resonance imaging (MRI) is used for diagnosing placenta accreta spectrum disorders (PASDs) because of its advanced soft-tissue contrast and spatial resolution capabilities, offering better contrast, improved spatial resolution, and a wider field of view compared with ultrasound. Using a 1.5-Tesla MRI protocol with multiple sequences, MRI can detect indicative signs of PASD such as placental signal heterogeneity, interruption of the myometrium-placenta interface, and abnormal vascularization. Specific sequences such as T2 SSFSE, FIESTA, and T1-weighted and diffusion-weighted imaging are used to assess placental attachment, myometrial invasion, and intraplacental hemorrhages. Significant MRI findings include thick low-signal T2 intraplacental bands, invasions into the cervix or bladder, and abnormal periplacental vascularity. MRI complements ultrasound and is crucial for the prenatal diagnosis of PASD, aiding in treatment planning and patient management, thereby reducing the associated fetal and maternal morbidity and mortality. The objective of this pictorial review was to outline the placental MRI technique and review the main imaging findings in placental MRI for PASD. This review encompasses anonymized patient images obtained following written consent.

Background: Since magnetic resonance imaging (MRI) is an extensively used and fundamental diagnostic imaging method and anxiety is one of the most important confounding factors in its performance, using guided imagery is recommended.

Objective: This study aimed to assess the effectiveness of guided imagery on the anxiety of patients undergoing MRI in 2023.

Methods: 88 patients were randomly assigned to intervention and control groups. The intervention group listened to the nature-based guided imagery audio file during their scan, and the control group did not receive any intervention. Data were collected using demographic information and the Spielberger Anxiety Questionnaire before and after the scan.

Results: There was no significant difference between the 2 groups before the intervention regarding demographic data and anxiety. In the intervention group, the mean anxiety decreased from 104.0 ± 14.6 to 92.4 ± 9.0, showing a significant reduction in the level of anxiety in both subscales (state and trait) and the total score (P < 0.001), compared with the control group and before the intervention.

Conclusion: The results showed that using guided imagery could decrease anxiety levels in patients undergoing MRI. Since patients' anxiety is one of the most important nursing diagnoses, performing cognitive methods, including guided imagery, as a simple, safe, inexpensive, and effective intervention should be considered.

Objectives: The radiological imaging industry is developing and starting to offer a range of novel artificial intelligence software solutions for clinical radiology. Deep learning reconstruction of magnetic resonance imaging data seems to allow for the acceleration and undersampling of imaging data. Resulting reduced acquisition times would lead to greater machine utility and to greater cost-efficiency of machine operations.

Materials and methods: Our case shows images from magnetic resonance arthrography under traction of the right hip joint from a 30-year-old, otherwise healthy, male patient.

Results: The undersampled image data when reconstructed by a deep learning tool can contain false-positive cartilage delamination and false-positive diffuse cartilage defects.

Conclusions: In the future, precision of this novel technology will have to be put to thorough testing. Bias of systems, in particular created by the choice of training data, will have to be part of those assessments.

Background: Altered size in the corpus callosum (CC) has been reported in individuals with autism spectrum disorder (ASD), but few studies have investigated younger children. Moreover, knowledge about the age-related changes in CC size in individuals with ASD is limited.

Objectives: Our objective was to investigate the age-related size of the CC and compare them with age-matched healthy controls between the ages of 2 and 18 years.

Methods: Structural-weighted images were acquired in 97 male patients diagnosed with ASD; published data were used for the control group. The CC was segmented into 7 distinct subregions (rostrum, genu, rostral body, anterior midbody, posterior midbody, isthmus, and splenium) as per Witelson's technique using ITK-SNAP software. We calculated both the total length and volume of the CC as well as the length and height of its 7 subregions. The length of the CC measures was studied as both continuous and categorical forms. For the continuous form, Pearson's correlation was used, while categorical forms were based on age ranges reflecting brain expansion during early postnatal years. Differences in CC measures between adjacent age groups in individuals with ASD were assessed using a Student t-test. Mean and standard deviation scores were compared between ASD and control groups using the Welch t-test.

Results: Age showed a moderate positive association with the total length of the CC (r = 0.43; Padj = 0.003) among individuals with ASD. Among the subregions, a positive association was observed only in the anterior midbody of the CC (r = 0.41; Padj = 0.01). No association was found between the age and the height of individual subregions or with the total volume of the CC. In comparison with healthy controls, individuals with ASD exhibited shorter lengths and heights of the genu and splenium of the CC across wide age ranges.

Conclusion: Overall, our results highlight a distinct abnormal developmental trajectory of CC in ASD, particularly in the genu and splenium structures, potentially reflecting underlying pathophysiological mechanisms that warrant further investigation.

Abstract: In this case report, we describe a 76-year-old woman, presenting with dizziness for the past 2 months, without other focal neurological signs. A magnetic resonance imaging of the brain was ordered by her GP. The MRI demonstrated multiple ring-enhancing lesions, both supratentorial and infratentorial. Lumbar puncture showed normal findings, in particular a normal cell count and culture. Because of the radiologic appearance, initially thought to be suggestive of cerebral abscesses, antibiotics were started. However, further workup revealed a new diagnosis of a stage IV (metastatic) small cell lung carcinoma, making diffuse brain metastases more likely. The patient was transferred to oncology/pneumology, where she was started on whole-brain radiotherapy, after which systemic therapy would start. However, because of further clinical deterioration, she was admitted at the palliative ward, where she died only 3 months after the initial presentation. In this case report, we emphasize the importance of keeping a broad differential diagnosis and briefly review the various possible pathologies causing ring-enhancing lesions.

Background: Currently, there is no evidence that MRI produces harmful effects on premature newborns, as well as short-term and long-term safety issues regarding radiofrequency fields and loud acoustic environment, while the examination that is being performed has not been clearly investigated. MRI of the brain conducted on preterm infants should be part of the diagnostic workup, when necessary. This article is intended to evaluate the short-term safety of MRI performed in preterm infants, when required, by analyzing all vital parameters available before, during, and after the MRI procedures.

Methods: We conducted a systematic review of the literature on electronic medical databases (PubMed and ClinicalTrials.gov) following the Preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We included all preterm infants who underwent MRI whose clinical, hemodynamic, and respiratory parameters were reported. The quality of the included articles was assessed using QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) tool.

Results: Six studies were included with a total of 311 preterm infants. No severe adverse event, such as death, occurred during MRI procedures. Vital signs remained stable in about two-thirds of all patients.

Conclusions: Given the general clinical safety of MRI, we suggest it as a tool to be used in preterm infants in Neonatal Intensive Care Units, when necessary. We further suggest the development of standard protocols to guide the use of MRI in preterm infants to maximize the clinical safety of the procedure.

Objectives: This study sought to prospectively investigate a novel quantitative biparametric prostate magnetic resonance imaging (MRI) protocol to detect prostate cancer (PCa) in biopsy-naïve men. Secondarily, this study reports the accuracy of fractional order calculus (FROC) diffusion and quantitative T2 compared with the Prostate Imaging Reporting & Data System (PI-RADS).

Methods: This prospective pilot study (NCT04175730) enrolled 50 prostate biopsy-naïve men who met eligibility criteria. All men received 3T MRI with T2 and diffusion-weighted imaging (DWI) (b-values: 50-4,000 s/mm2). Men with PI-RADS lesions ≥3 underwent targeted and systematic prostate biopsy, omitting systematic biopsy cores in peripheral zone lesions. DWI series images were fit to signal decay to calculate ADC (mm2/s) and the FROC model for coefficient DF (mm2/s). The primary end point was detection of Gleason grade group ≥2 (GG≥2) PCa. Receiver operating characteristic regression and area under the curve (AUC) were reported.

Results: Forty-eight men underwent MRI and biopsy. Mean age was 61.5 years (56-68), 29% were White, 52% were African American, mean PSA was 6.0 ng/mL (4.9-8.0), and mean PSA density was 0.14 ng/mL2. In total, 61 PI-RADS ≥3 lesions were targeted for biopsy. GG≥2 PC was found in 7% (1/14) of PI-RADS 3 lesions, 28% (10/36) of PI-RADS 4 lesions, and 36% (4/11) of PI-RADS 5 lesions. The AUC for detection of GG≥2 PC was 0.63 (0.5-0.76) for PI-RADS, 0.82 (0.68-0.96) for ADC, and 0.87 (0.77-0.97) for the FROC model.

Conclusion: This small prospective pilot study demonstrates the feasibility of a novel quantitative biparametic MRI protocol to detect prostate cancer in biopsy-naïve men.

Background: Longitudinal associations of noninvasive 2-dimensional phase-contrast magnetic resonance imaging (2D-PC-MRI) velocity markers of the superficial femoral artery (SFA) were analyzed along with the characteristics of peripheral artery disease (PAD). We hypothesized that the 2-year differences in MRI-based measures of SFA velocity were associated with longitudinal changes in markers of PAD.

Methods: A total of 33 (11 diabetic, 22 nondiabetic) patients with PAD with baseline and 2-year follow-up MRI scans were included in this secondary analysis of the Effect of Lipid Modification on Peripheral Artery Disease after Endovascular Intervention Trial (ELIMIT). Electrocardiographically gated 2D-PC-MRI was performed at a proximal and a distal location of the distal SFA territory. SFA lumen, wall, and total vessel volumes and the normalized wall index (NWI) were analyzed.

Results: Baseline characteristics did not differ between diabetic and nondiabetic PAD patients. Maximum proximal and distal SFA velocity measures did not differ between baseline and 2 years (41.98 interquartile range (IQR) (23.58-72.6) cm/s vs. 40.31 IQR (26.69-61.29) cm/s; P = 0.30). Pooled analysis (N = 33) showed that the 24-month change in the NWI was inversely associated with the 24-month change in the proximal maximal SFA velocity (beta = -168.36, R2 = 0.150, P value = 0.03). The 24-month change of the maximum velocity differences between the proximal and distal SFA locations was inversely associated with the 24-month changes in peak walking distance (beta = -0.003, R2 = 0.360, P value = 0.011).

Conclusion: The 2-year change of SFA plaque burden is inversely associated with the 2-year change of proximal peak SFA blood flow velocity. 2D-PC-MRI measured SFA velocity may be of interest in assessing PAD longitudinally.

Background: Skeletal bone age assessment for medical reasons is usually performed by conventional x-ray with use of ionizing radiation. Few pilot studies have shown the possible use of magnetic resonance imaging (MRI).

Purpose: To comprehensively evaluate feasibility and value of MRI for skeletal bone age (SBA) assessment in healthy male children.

Materials and methods: In this prospective cross-sectional study, 63 male soccer athletes with mean age of 12.35 ± 1.1 years were examined. All participants underwent 3.0 Tesla MRI with coronal T1-weighted turbo spin echo (TSE), coronal proton density (PD)-weighted turbo spin echo (TSE), and T1-weighted three-dimensional (3D) volume interpolated breath-hold examination (VIBE) sequence. Subsequently, SBA was assessed by 3 independent blinded radiologists with different levels of experience using the common Greulich-Pyle (GP) atlas and the Tanner-Whitehouse (TW2) method.

Results: In a mean total acquisition time of 5:04 ± 0:47 min, MR image quality was sufficient in all cases. MRI appraisal was significantly faster ( P < 0.0001) by GP with mean duration of 1:22 ± 0:08 min vs. 7:39 ± 0:28 min by TW. SBA assessment by GP resulted in mean age of 12.8 ± 1.2 years, by TW 13.0 ± 1.4 years. Interrater reliabilities were excellent for both GP (ICC = 0.912 (95% confidence interval [CI] = 0.868-0.944) and TW (ICC = 0.988 (95% CI = 0.980-0.992) and showed statistical significance ( P < 0.001). Subdivided, for GP, ICCs were 0.822 (95% CI = 0.680-0.907) and 0.843 (95% CI = 0.713-0.919) in Under 12 and Under 14 group. For TW, ICCs were 0.978 (95% CI = 0.958-0.989) in Under 12 and 0.979 (95% CI = 0.961-0.989) in Under 14 group.

Conclusion: MRI is a clinically feasible, rapidly evaluable method to assess skeletal bone age of healthy male children. Using the Greulich-Pyle (GP) atlas or the Tanner-Whitehouse (TW2) method, reliable results are obtained independent of the radiologist's experience level.

Objectives: Locally low-rank (LLR) denoising of functional magnetic resonance imaging (fMRI) time series image data is extended to multi-echo (ME) data. The proposed method extends the capabilities of non-physiologic noise suppression beyond single-echo applications with a dedicated ME algorithm.

Materials and methods: Following an institutional review board (IRB) approved protocol, resting-state fMRI data were acquired in 7 healthy subjects. A compact 3T scanner enabled whole-brain acquisition of multiband ME fMRI data at high spatial resolution (1.4 × 1.4 × 2.8 mm 3 ) with a 1810 ms repetition time (TR). Image data were denoised with ME-LLR preceding functional processing. The results of connectivity maps generated from denoised data were compared with maps generated with equivalent processing of non-denoised images. To assess ME-LLR as a method to reduce scan time, comparisons were made between maps computed from image data with full and retrospectively truncated durations. Assessments were completed with seed-based connectivity analyses using echo-combined image data. In a feasibility assessment, nondenoised and denoised full-duration echo-combined data were equivalently processed with independent component analysis (ICA) and compared.

Results: ME-LLR denoising yielded strengthened resting-state network connectivity maps after nuisance regression and seed-based connectivity analysis. In assessing ME-LLR as a scan reduction mechanism, maps generated from denoised data at half scan time showed comparable quality with maps generated from full-duration, non-denoised data, at both single subject and group levels. ME-LLR substantially increased temporal signal-to-noise ratio (tSNR) for image data respective to each individual echo and for image data after nuisance regression. Among echo-specific image volumes, increases in tSNR yielded by ME-LLR were most pronounced for image data with the longest echo time and thereby lowest SNR. ICA showed resting-state networks consistently identified between non-denoised and denoised data, with clearer demarcation of networks for ME-LLR.

Conclusions: ME-LLR is demonstrated to suppress non-physiologic noise, enhance functional connectivity map quality, and could potentially facilitate scan time reduction in ME-fMRI.