Citations

Abstract Photon-counting detector CT (PCD-CT) directly detects individual photons and measures their energies, enabling the acquisition of multi-energy data from a single x-ray source with higher spatial resolution, thereby allowing visualization of smaller arteries and veins and other important imaging features not seen at conventional CT. It also substantially reduces calcium and stent blooming artifacts. Appropriate patient selection and task-based optimization of acquisition, reconstruction, and interpretation are critical to realize these benefits. Vascular imaging examinations for which early evidence shows that PCD-CT demonstrates higher diagnostic performance compared to conventional CT include coronary CT angiography (CTA) for evaluation of partially calcified plaques or stents, peripheral runoff CTA, detection of cerebrospinal fluid-venous fistulas, and head CTA for evaluation of small intracranial vessels and aneurysms. Current limitations include excessive image noise with the sharpest reconstruction kernels and challenges when adapting conventional CT protocols (eg, requiring sharper kernels, thinner slices, higher matrices, tailored scan modes) to achieve time-efficient image reconstruction and hanging protocols. New solutions and directions will include deep-learning-based image noise reduction, improved spectral separation, strategic triage of specific patient populations to PCD-CT systems, and subspecialty clinical practice recommendations for this new technology.

Abstract BACKGROUND Patients with primary brain tumors often have very complex histories, but an accurate understanding of their care timeline is critical to provide the best care possible. Extracting pertinent facts from the medical record can be time consuming and frustrating. We sought to apply generative AI large language models (LLM) to this problem in order to supply providers with concise, accurate, and focused data including graphs and tables. METHODS After evaluating multiple LLMs, GEMINI 2.5 Pro was selected. Prompt engineering was iteratively refined across a range of patients to generate concise outputs using tables, graphs, and prose to describe timing of chemoradiation, tumor markers, procedures, and trends in MRI results. The model inferred BT-RADS scores from the MRI report prose. Using a 5-point Likert scale, neuroradiologists assessed the AI-output both prospectively and retrospectively comparing it to the medical record. LLM’s compared AI summaries to source material. RESULTS Six neuroradiologists each ranked 25 prospective patient outputs as accurate (82%/16%/1%), useful (94%/6%/0%), trustworthy (86%/13%/1%), and satisfactory (86%/10%/1%) for Likert ratings of highly agree/agree/neutral, respectively. No responses were disagree or highly disagree. Interobserver agreement was high (Gwent AC2 > 0.95). The LLM evaluation of referenced portions of the record determined > 85% of summary statements were supported by source documents. While users estimated time savings of a 1-10 minutes per case, they felt the greater benefit was having more organized data presented efficiently. CONCLUSIONS AI summaries of the medical record of complex patients with primary brain tumors give providers an accurate, well-organized display of the pertinent facts necessary for high quality care and save time in chart review. These summaries, which are generated early each morning, have been found to be helpful and are now being incorporated into our clinical practice and multidisciplinary tumor board.

ABSTRACT Background Facet Joint Septic Arthritis (FJSA) is an infection of the spinal facet joints, for which previously described imaging findings are non‐specific. We present MRI findings of 20 patients who underwent facet biopsy for possible FJSA. Materials and Methods An internal database was reviewed for cases who underwent image‐guided spinal facet biopsy for possible infection and had pre‐biopsy contrast‐enhanced MRI. Cases were categorized as biopsy FJSA positive or negative and MRI was reviewed for synovitis, bone marrow enhancement, epidural phlegmon/abscess, and paraspinal muscle enhancement. The MRI findings were considered extensive if the involvement of the posterior paraspinal muscles spanned at least two vertebral bodies in the craniocaudal direction and at least half the length of the muscles in the anterior‐posterior direction. Results Twenty patients were included. Nine patients were FJSA positive, all of whom had synovitis, bone marrow enhancement of the facet joints, and epidural phlegmon. No patients had epidural abscess, but five patients had a paraspinal abscess. All nine patients demonstrated extensive paraspinal muscular enhancement. Eleven biopsy cases that were negative for FSJA were included. Their MRI findings demonstrated all with synovitis, six with bone marrow enhancement of the facet joints, six with epidural phlegmon, none with epidural abscess, and none with paraspinal abscess. Only one FJSA negative case had extensive paraspinal muscle enhancement. Conclusion The MRI appearance of FJSA has rarely been described in the literature; however, the diagnosis has a significant clinical impact. Facet enhancement with florid posterior paraspinal muscle enhancement should raise suspicion for FSJA.

Abstract To propose a novel entity of possible intraosseous pseudoprogression in clival chordoma following proton radiation therapy (PRT). A total of 38 consecutive patients who underwent surgical resection followed by PRT for clival chordoma between January 2015 and December 2023 were analyzed retrospectively. Follow-up magnetic resonance imaging (MRI) suggesting recurrence or progression was evaluated for validity. Apparent diffusion coefficient (ADC) and tumor-to-brainstem signal intensity ratio on contrast-enhanced T1-weighted imaging (Rce) were assessed. Pseudoprogression was defined as (1) MRI signs of recurrence or progression with no pathological confirmation despite obtaining a specimen, or (2) MRI signs of recurrence or regression with spontaneous resolution/regression. Of the 11 patients with MRI findings suggestive of recurrence or progression, 3 were diagnosed with recurrence, 5 with progression, and 3 with pseudoprogression. Patients with pseudoprogression were significantly younger than those with progression (p = 0.04), and all were female. The median time to recurrence, progression, and pseudoprogression was 31, 29, and 21 months, respectively. The three pseudoprogression cases were managed with gross-total resection followed by stereotactic radiosurgery, extensive biopsy, and observation, respectively. Although statistical significance was not reached, ADC (p = 0.33) and Rce (p = 0.13) tended to be higher in pseudoprogression cases. After PRT for clival chordoma, intraosseous pseudoprogression should be considered in the differential diagnosis, particularly in relatively young female patients, although the role of ADC and Rce on MRI remains inconclusive. Multidisciplinary teams managing chordomas should take this into account when determining the aggressiveness of treatment in such cases.

Rosai–Dorfman Disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare non-Langerhans cell histiocytic neoplasm. Although the disease classically presents as massive painless lymphadenopathy in young adults, RDD can also involve the central nervous system in some patients. CNS lesions, can cause headaches, neurologic deficits, and even neurologic deficits. The imaging appearance of CNS RDD typically mimics that of meningiomas: well-circumscribed dural-based lesions that often have dural tails. However, some imaging clues also exist that might help a radiologist recognize RDD, even before histopathologic confirmation. This radiology-pathology report of a patient with CNS RDD highlights the most pertinent clinical, imaging, and pathologic features of CNS RDD, and discusses what the neuroradiologist needs to know about the disease.

AbstractBackgroundCochlear implants (CIs) are used to rehabilitate moderate to profound sensorineural hearing loss and stimulate the auditory system via a multichannel electrode array positioned in the scala tympani. Imaging evaluation of CIs is substantially degraded by metallic artifacts. Photon‐counting detector (PCD)‐CT has the potential to minimize such artifacts, though this has not been convincingly established in prior studies. This study compared the visualization of CI electrodes on PCD‐CT to conventional energy integrating detector (EID)‐CT.Materials and MethodsFive patients with CIs were prospectively recruited to undergo temporal bone imaging on both EID‐CT and PCD‐CT scanners yielding 2D and 3D Volume Rendering Technique (VRT) images. Three nonblinded neuroradiologists reviewed 2D and 3D VRT images for the ability to resolve CI electrode leads using a Likert scale. The average Likert scores of PCD‐CT versus EID‐CT were calculated for each reader for both 2D and 3D VRT images. (Likert scores 1–5 based on inferior to superior rating of PCD‐CT compared to EID‐CT). Inter‐rater agreement was assessed using Krippendorff's alpha with ordinal weights. ResultsFive patients underwent temporal bone CT for CI array evaluation. As evidenced by 5‐point Likert scales that were independently used by the three reviewers, this study demonstrated superior resolution of CI electrode array using PCD‐CT as compared to EID‐CT with an average score of 4.2 ± 0.8 for 2D images and 4.9 ± 0.4 for 3D VRT images.ConclusionsPCD‐CT is superior to EID‐CT in the visualization of CI electrodes, particularly in 3D VRT imaging.

Dilated perivascular spaces (PVSs) are common and easily recognized on imaging. However, rarer giant tumefactive PVSs (GTPVSs) can have unusual multilocular cystic configurations, and are often confused for other pathologic entities, including neoplasms, cystic infarctions, and neuroepithelial cysts. Because GTPVSs are scarcely encountered and even more infrequently operated upon, many radiologists are unaware of the imaging and pathologic features of these lesions. Here, a case of a resected GTPVS is presented, highlighting both its radiologic and histologic characteristics, and discussing how such lesions can be differentiated from their closest mimickers on imaging.