Mark, Ian

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.

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.

Background and Purpose Spontaneous intracranial hypotension (SIH) is caused by spinal cerebrospinal fluid (CSF) leaks. This study assessed whether the certainty and/or multifocality of CSF leaks is associated with the severity of intracranial sequelae of SIH. Materials and Methods A retrospective review was completed of patients with suspected SIH that underwent digital subtraction myelogram (DSM) preceded by brain MRI. DSMs were evaluated for the presence or absence of a CSF leak, categorized both as positive/negative/indeterminate and single versus multifocal. Brain MRIs were assessed for intracranial sequelae of SIH based on two probabilistic scoring systems (Dobrocky and Mayo methods). For each system, both an absolute “numerical” score (based on tabulation of findings) and “categorized” score (classification of probability) were tabulated. Results 174 patients were included; 113 (64.9%) were female, average age 52.0 ± 14.3 years. One or more definite leaks were noted in 76 (43.7%) patients; an indeterminate leak was noted in 22 (12.6%) patients. 16 (16.3%) had multiple leaks. There was no significant difference in the severity of intracranial findings between patients with a single versus multiple leaks ( p values ranged from .36 to .70 using categorized scores and 0.22–0.99 for numerical scores). Definite leaks were more likely to have both higher categorized intracranial scores (Mayo p = .0008, Dobrocky p = .006) and numerical scores ( p = .0002 for Mayo and p = .006 for Dobrocky). Conclusions Certainty of a CSF leak on diagnostic imaging is associated with severity of intracranial sequelae of SIH, with definite leaks having significantly more intracranial findings than indeterminate leaks. Multifocal leaks do not cause greater intracranial abnormalities.

Intrathecal blood after a percutaneous epidural blood patch is a known complication, one that has been previously attributed to inadvertent needle tip position in the subarachnoid space. We present two cases with imaging confirmation of an alternative mechanism, one that includes blood transferring from the epidural space to the subarachnoid space through a pre-existing dural defect.

CT myelography has been traditionally used to evaluate post-operative paraspinal fluid collections to discern CSF leaking into a pseudomeningocele versus a contained seroma. Rather than performing a lumbar puncture and injecting intrathecal contrast for myelography, we present the first report of direct contrast injection into a post-operative paraspinal pseudomeningocele for CSF leak confirmation and localization. This is a simple procedure that has several advantages over a conventional CT myelogram for the evaluation of post-operative paraspinal fluid collections.

Background Cerebrospinal fluid-venous fistulas (CSFVF) are a common cause of spontaneous intracranial hypotension (SIH). Transvenous embolization has emerged as a reliable treatment option. We review the clinical presentation, imaging, and clinical outcomes of 100 consecutive CSFVF patients who underwent embolization over 2 years. Methods Baseline clinical characteristics, imaging findings (including Bern SIH score), technical outcomes, and long-term imaging and clinical outcomes were collected. All patients had at least 3 months of clinical follow-up and had baseline MRI. 99/100 patients underwent follow-up imaging at ≥3 months post-treatment. Results 100 patients were included. Mean imaging and clinical follow-up duration was 8.3±7.7 months and 15.0±6.8 months, respectively. The mean duration of symptoms before embolization was 40.9±52 months. Mean baseline Bern SIH score was 5.9±3.3. The most common baseline symptoms were headache (96 patients), tinnitus (55 patients), and cognitive dysfunction (44 patients). Technical success rate was 100%. Mean post-treatment Bern SIH score was 0.9±1.6 (P<0.0001). Following treatment, 95% of patients reported significant improvement or resolution in symptoms (58 patients reporting resolution and 37 reporting improvement). 5 patients reported no improvement. There were no major procedural or periprocedural complications. 10 patients had minor procedural complications that did not result in any change in management (Onyx emboli, venous perforation). 19 patients had rebound intracranial hypertension requiring acetazolamide therapy. 7 patients had recurrent fistula at the initially treated level. Conclusions Transvenous embolization of CSFVF in SIH patients is safe and effective with a 95% treatment response, significant improvement in imaging outcomes, and a very low rate of complications.

We present an updated ultrafast dynamic computed tomography myelography technique that can be used for the localization of spontaneous spinal cerebrospinal fluid leaks in the setting of spontaneous intracranial hypotension. This has over twice the temporal resolution of previously described techniques at the same radiation dose output.