AJNR. American journal of neuroradiology最新文献

Background and purpose: Pituitary microadenomas can be challenging to see on MRI, particularly when they are small. The detection of microadenomas commonly relies on contrast-enhanced sequences, highlighting the adenoma that demonstrates hypoenhancement relative to the native pituitary on T1-weighted sequences. Detecting adenomas in patients with Cushing disease is crucial, as surgery is the standard of care treatment. Accurate pre-operative lesion localization is directly associated with improved outcomes. The purpose of our study was to determine the utility of contrast-enhanced CISS/FIESTA-C for identifying pituitary microadenomas in patients with Cushing disease.

Materials and methods: This cross-sectional study retrospectively reviewed pituitary MR images in patients with Cushing disease who had post-contrast CISS/FIESTA-C. Images were evaluated for lesion conspicuity (well-defined margins), as well as the signal intensity of the adenoma and native pituitary. The normalized signal intensity difference (nSID) was calculated by subtracting the lesion signal intensity from the pituitary signal intensity, and dividing by the pituitary signal intensity. Patient age, sex, and diagnosis based on intraoperative findings, pathology results, and post-operative adrenal insufficiency were recorded.

Results: 17 patients (15 female) were included in this study. 16 (94%) adenomas were discrete on CISS/FIESTA-C compared to 11 (65%) on T1-weighted imaging. The mean adenoma nSID with CISS/FIESTA-C was 0.512 (SD 0.12), relative to 0.242 (SD 0.15) on T1-weighted imaging (p<0.001).

Conclusion: In comparison to MRI T1-weighted images, contrast-enhanced CISS/FIESTA-C imaging detects a higher number of pituitary microadenomas with superior conspicuity. As up to 50% of patients with Cushing disease present without a pituitary lesion detect on MRI, post contrast CISS/FIESTA-C may be especially valuable as an additional sequence in this population.

Abbreviations: CISS = Constructive interference in steady state; FIESTA-C = fast imaging employing steady-state acquisition with cycling; SI = Signal Intensity, nSID = normalized signal intensity difference.

Laser interstitial thermal therapy (LITT) is a minimally invasive cytoreductive treatment option for patients with intracranial tumors. Utilizing real-time MR thermometry, LITT delivers tailored, targeted, and permanent cytotoxic thermal injury to intra-axial pathology. As a minimally invasive and nonionizing treatment option proved to be an effective, less morbid, and more efficient alternative to surgery, the utility of LITT has rapidly expanded. Along with this growth comes the need for neurosurgeons and neuroradiologists to accurately assess the radiographic outcomes of LITT in a standardized, dependable, and longitudinal fashion. We present a comprehensive overview of the indications and mechanisms of action of LITT for intra-axial brain tumors as well as guidance on thorough pre-, intra-, and postoperative imaging assessments. Using detailed case examples describing the contemporary uses of LITT, we hope to provide a foundational understanding of LITT that will inform imaging assessment and guide accurate multi disciplinary tumor board discussion.

Background: Long-term posttreatment surveillance imaging algorithms for head and neck squamous cell carcinoma are not standardized due to debates over optimal surveillance strategy and efficacy. Consequently, current guidelines do not provide long-term surveillance imaging recommendations beyond 6 months.

Purpose: We performed a systematic review to evaluate the impact of long-term imaging surveillance (ie, imaging beyond 6 months following completion of treatment) on survival in patients treated definitively for head and neck squamous cell carcinoma.

Data sources: A search was conducted on PubMed, EMBASE, Scopus, the Cochrane Central Register of Controlled Trials, and the Web of Science for English literature published between 2003 and 2024 evaluating the impact of long-term surveillance imaging on survival in patients with head and neck squamous cell carcinoma.

Study selection: We screened 718 abstracts and performed full-text review for 95 abstracts, with 2 articles meeting the inclusion criteria. The Risk of Bias in Non-Randomized Studies of Interventions assessment tool was used.

Data analysis: A qualitative assessment without a pooled analysis was performed for the 2 studies meeting inclusion criteria.

Data synthesis: No randomized prospective controlled trials were identified. Two retrospective 2-arm studies were included comparing long-term surveillance imaging with clinical surveillance and were each rated as having a moderate risk of bias. Each study included heterogeneous populations with variable risk profiles and imaging surveillance protocols. Both studies investigated the impact of long-term surveillance imaging on overall survival and came to different conclusions, with 1 study reporting a survival benefit for long-term surveillance imaging with FDG-PET/CT in patients with stage III or IV disease or an oropharyngeal primary tumor and the other study demonstrating no survival benefit.

Limitations: Limited heterogeneous retrospective data available precludes definitive conclusions on the impact of long-term surveillance imaging in head and neck squamous cell carcinoma.

Conclusions: There is insufficient quality evidence regarding the impact of long-term surveillance imaging on survival in patients treated definitively for head and neck squamous cell carcinoma. There is a lack of a standardized definition of long-term surveillance, variable surveillance protocols, and inconsistencies in results reporting, underscoring the need for a prospective multicenter registry assessing outcomes.

Background and purpose: This retrospective study evaluated the utility of contrast-enhanced (CE) T1-weighted 3D fast spinecho-based SPACE sequences for brain metastasis detection on 3T MRI compared to gradient recalled-echo-based 3D fast low-angle shot (FLASH) sequence.

Materials and methods: We identified all patients at a single institution who underwent SPACE and 3D FLASH sequences as part of a practice quality improvement project. Their medical records were retrospectively reviewed. Five certified neuroradiologists reviewed the images, with at least 2 weeks separation between scoring sequences for the same patient. The following parameters were evaluated: number of metastatic lesions, number of indeterminate lesions, lesion margin, contrast-to-noise ratio (CNR), extent of image artifacts, and overall image quality. CNR was also quantified for solidly enhancing lesions > 1 cm.

Results: We identified 220 patients who underwent SPACE and 3D FLASH sequences (the order of the sequences was equally distributed). Of these, 79 had brain metastases on imaging, and 7 were excluded; thus, 72 patients were included in the study. Twenty patients were scored by 2 radiologists. Out of the 92 evaluations, SPACE detected more lesions than did 3D FLASH in 35, while 3D FLASH detected more lesions in 10. More indeterminate lesions were seen on 3D FLASH (27) than on SPACE (9). For lesion margin, CNR, and overall image quality on a Likert scale, SPACE performed significantly better than did 3D FLASH, with less image artifacts (P < 0.00001). Higher quantitative CNRs were found on SPACE than on 3D FLASH images, although this result was not statistically significant (median = 22.9 vs. 15.5, respectively, P = 0.134). There was a high inter-reader lesion detection concordance with Krippendorf's alpha ordinals at 0.962 for SPACE, 0.870 for 3D FLASH, and 0.918 for the two sequences combined.

Conclusions: Compared with 3D FLASH, the SPACE sequence detected more metastatic lesions and was rated higher for image quality, lesion margin, and CNR, with fewer artifacts. Importantly, the SPACE sequence resulted in increased reader confidence, with fewer indeterminate lesions detected.

Abbreviations: FLASH = fast low-angle shot; FSE = fast spin-echo; GRE = gradient-recalled echo; MP-RAGE = magnetization-prepared rapid gradient echo; SPACE = Sampling Perfection with Application-optimized Contrasts using different flip angle Evolution; VIBE = volumetric interpolated breath-hold examination.

Background and purpose: Differentiating radiation necrosis (RN) from tumor progression (TP) after radiation therapy for brain metastases is an important clinical problem requiring advanced imaging techniques that may not be widely available and are challenging to perform at multiple time points. The ability to leverage conventional MRI for this problem could have a meaningful clinical impact. The purpose of this study was to explore contrast-enhanced T2 FLAIR (T2FLAIRc) as a new imaging biomarker of RN and TP.

Materials and methods: This single-institution retrospective study included patients with treated brain metastases undergoing DSC-MRI between January 2021 and June 2023. Reference standard assessment was based on histopathology or serial follow-up, including the results of DSC-MRI for a minimum of 6 months from the first DSC-MRI. The index test was implemented as part of the institutional brain tumor MRI protocol and preceded the first DSC-MRI. T2FLAIRc and gadolinium-enhanced T1 (T1c) MPRAGE signal were normalized against normal brain parenchyma and expressed as a z score. The mean signal intensity of enhancing disease for the RN and TP groups was compared using an unpaired t test. Receiver operating characteristic curves and area under the receiver operating characteristic curve (AUC) were derived by bootstrapping. The DeLong test was used to compare AUCs.

Results: Fifty-six participants (mean age, 62 [SD, 12.7] years; 39 women; 28 with RN, 28 with TP) were evaluated. The index MRI was performed, on average, 73 [SD, 34] days before the first DSC-MRI. Significantly higher z scores were found for RN using T2FLAIRc (8.3 versus 5.8, P < .001) and T1c (4.1 versus 3.5, P = .02). The AUC for T2FLAIRc (0.83; 95% CI, 0.72-0.92) was greater than that for T1c (0.70; 95% CI, 0.56-0.83) (P = .04). The AUC of DSC-derived relative CBV (0.82; 95% CI, 0.70-0.93) was not significantly different from that of T2FLAIRc (P = .9).

Conclusions: A higher normalized T1c and T2FLAIRc signal intensity was found for RN. In a univariable test, the mean T2FLAIRc signal intensity of enhancing voxels showed good discrimination performance for distinguishing RN from TP. The results of this work demonstrate the potential of T2FLAIRc as an imaging biomarker in the work-up of RN in patients with brain metastases.

This technical report describes use of a novel, conformable receive-only radiofrequency coil for 3T magnetic resonance (MR) neurography in a cohort of patients with occipital neuralgia. Applying a sub-millimeter, isotropic three-dimensional double-echo steady-state sequence, detailed visualization of the occipital nerves and associated pathologies could be achieved.ABBREVIATIONS: ABC＝ definition; XYZ＝ definition. FACE＝ Flexible Array coil for Cervical and Extraspinal; DESS＝ double-echo steady-state; C1, C2, C3＝ First, second, and third cervical vertebrae respectively.

In recent years, generative artificial intelligence (AI), particularly large language models (LLMs) and their multimodal counterparts, Multi-Modal Large Language Models (MM-LLMs), including Vision Language Models (VLMs), have generated considerable interest in the global AI discourse. LLMs, or pre-trained language models (such as ChatGPT, Med-PaLM, LLaMA, etc.), are neural network architectures trained on extensive text data, excelling in language comprehension and generation. MM-LLMs, a subset of foundation models, are trained on multimodal datasets, integrating text with another modality, such as images, to better learn universal representations akin to human cognition. This versatility enables them to excel in tasks like chatbots, translation, and creative writing while facilitating knowledge sharing through transfer learning, federated learning, and synthetic data creation.Several of these models can have potentially appealing applications in the medical domain, including, but not limited to, enhancing patient care by processing patient data, summarizing reports and relevant literature, providing diagnostic, treatment, and follow-up recommendations, and ancillary tasks like coding and billing. As radiologists enter this promising but uncharted territory, it is imperative for them to be familiar with the basic terminology and processes of LLMs. Herein, we present an overview of the LLMs and their potential applications and challenges in the imaging domain.ABBREVIATIONS: AI: Artificial Intelligence; BERT: Bidirectional Encoder Representations from Transformers; CLIP: Contrastive Language-Image Pretraining; FM: Foundation Models; GPT: Generative Pre-trained Transformer; LLM: Large language model; NLP: natural language processing; VLM: Vision Language Models.

Post-dural puncture headache is an increasingly recognized cause of chronic headache. Outside of clinical history and myelography that requires an additional dural puncture, there is no reliable diagnostic test to evaluate for persistent dural defects. We describe the injection of iodinated contrast into the dorsal epidural space under CT guidance in 5 patients as a potential tool to visualize persistent dural defects.

Transcranial focused ultrasound (FUS) is a versatile, MR-guided, incisionless intervention with diagnostic and therapeutic applications for neurologic and psychiatric diseases. It is currently FDA-approved as a thermoablative treatment of essential tremor and Parkinson disease. However, other applications of FUS including BBB opening for diagnostic and therapeutic applications, sonodynamic therapy, histotripsy, and low-intensity focused ultrasound neuromodulation are all in clinical trials. While FUS targeting for essential tremor and Parkinson disease has classically relied on an indirect, landmark-based approach, development of novel, advanced MR imaging techniques such as DTI tractography and fast gray matter acquisition T1 inversion recovery has the potential to improve individualized targeting and thus potentially enhance treatment response, decrease treatment times, and avoid adverse effects. As the technology advances and the number of clinical applications increases, the role of the neuroradiologist on a multidisciplinary team will be essential in pairing advanced structural and functional imaging to further this image-guided procedure via a precision medicine approach. This multi-institutional report, written by an experienced team of neuroradiologists, neurosurgeons, and neurologists, summarizes current practices, the use of advanced imaging techniques for transcranial MR-guided high-intensity FUS, recommendations for clinical implementation, and emerging clinical indications.

Background and purpose: The role of the venous compartment in cerebral small vessel disease has yet to be fully understood. As such, we evaluated how deep medullary veins integrity relates to MRI-based small vessel disease severity markers and glymphatic function assessed by DTI measures in patients with a recent small subcortical infarct.

Materials and methods: We gathered demographic, clinical, and 3 Tesla-MRI imaging data from 50 patients with a recent small subcortical infarct. We evaluate the venular integrity using two visual scales based on their appearance on SWI. We assessed the number of lacunes and microbleeds, white matter hyperintensities volume, perivascular spaces volume in basal ganglia and white matter, summary-small vessel disease score, and brain volume. Diffusivity measures in normal-appearing white matter included free water fraction, mean diffusivity and fractional anisotropy with and without free water correction, and DTI along the perivascular spaces. After categorizing the cohort in quartiles according to both venular scores, we assessed their correlations with small vessel disease markers and diffusivity measures using multivariable ordinal regression analyses adjusting for age, sex, smoking, and summary small vessel disease score.

Results: In univariate analysis most of the imaging variables, except for microbleeds, perivascular spaces in white matter and DTI-along the perivascular spaces, were associated with one or both venular scores. In multivariate analysis (OR, 95% CI), free water (1.33, 1.03-1.73), mean diffusivity (4.56, 1.32-15.81), fractional anisotropy (0.77, 0.63-0.93), free water-corrected mean diffusivity and fractional anisotropy (2.39, 1.06-5.39;0.78, 0.65-0.94, respectively), associated with vein appearance, while only brain volume (0.48, 0.25-0.94), fractional anisotropy with and without free water correction (0.82,0.86-0.99; 0.83, 0.7-0.99, respectively) remained significant for vein count.

Conclusions: In patients with a recent small subcortical infarct, disruption of the deep medullary veins, increased extracellular water, and white matter injury appear to be associated.

Abbreviations: SVD=small vessel disease; DMV=deep medullary veins; WMH=white matter hyperintensities; PVS=perivascular spaces; DTI-ALPS=diffusion tensor image analysis along the perivascular spaces; FW=free water; MD=mean diffusivity; FA= fractional anisotropy; BG=basal ganglia.