Faculty Bibliography

The transsphenoidal corridor for pituitary adenoma surgery was established as early as 1906 by Schloffer and was subsequently refined by Cushing throughout the early 20thcentury [1]. The use of intraoperative magnetic resonance imaging (iMRI) in endoscopic endonasal transsphenoidal resections, however, is a relatively contemporary addition to the surgical treatment of pituitary tumors. The morbidity of these cases has decreased over the years in light of advances in intraoperative navigation as well as improvements in endoscope dynamics and surgical instruments. Despite such improvements, a substantial number of patients require repeat surgeries or subsequent radiotherapy for residual and/or recurrent disease. This can be largely attributed to cavernous sinus invasion or suprasellar extension, which pose technical challenges to achieving gross total resections (GTRs). The rate of GTR for pituitary tumors cited in the literature varies from 59-88%.[2-3] The advantage of iMRI is that it provides the surgeon with immediate feedback regarding their progress and ability to safely achieve GTR which, in pituitary surgery, is critical for long term cure. Additionally, although there is concern for increased risk of postoperative endocrine dysfunction, Zhibin et al prove that this is not necessarily the case. In their series, 133 patients who underwent iMRI had higher rates of GTR and did not have a significant difference in postoperative hypopituitarism. [4] This study includes a combined retrospective and prospective comparative analysis of 238 patients who underwent transsphenoidal resection of a pituitary tumor from January 2013 until May 2019. All patients were operated on by one of four experienced neurosurgeons and one of three experienced otolaryngologists. There were 203 patients who did not undergo iMRI and 25 patients who did. A 3 tesla MRI magnet was used in all cases. All intraoperative images were read and interpreted by a senior neuroradiologist at our institution. Amongst the two groups, there was no statistically significant difference in patient age (p = 0.488), tumor size (microadenoma versus macroadenoma, p = 0.878), and primary versus recurrent tumor (p = 0.837). The use of iMRI did not yield a decrease in the length of stay (4.84 days in the no iMRI group and 5 in the iMRI group, p = 0.777). There were zero cases of a return to the OR for residual tumor in the intraoperative MRI group versus the non-MRI group. However, this did not reach statistical significance. This study did not yield a statistically significant difference in GTR (p = 0.75), near total resection (NTR, p = 0.167), or subtotal resection (p = 0.083). This is likely secondary to a low sample size and therefore power in the iMRI group. Finally, there was no significant difference in the number of patients requiring postoperative DDAVP (p = 0.099) or hydrocortisone (p = 0.873) after discharge. Preliminary results reveal a potential benefit of iMRI use to assess for residual disease which can be addressed immediately during the initial operation, thus decreasing the need for re-operations. Furthermore, the ability to correlate intraoperative findings with an intraoperative structure may lead to more precise identification and preservation of normal gland, which can possibly decrease the incidence of postoperative endocrine dysfunction

BACKGROUND:Spinal epidural lipomatosis (SEL) is a rare condition defined as pathological overgrowth of the normally present epidural fat within the spinal canal. SEL is associated with Cushing disease, obesity and chronic corticosteroid therapy. Diabetes mellitus type 1 (DM1) has not known to be a risk factor for SEL. The neurological symptoms of SEL are attributed mainly to mechanical compression on the spinal cord and the cauda equina. METHODS:A retrospective chart review of patients evaluated at NYU Multiple Sclerosis Care Center identified three diabetic patients with progressive myelopathy associated with SEL. We report the clinical course, diagnostic workup and outcomes in these three patients with SEL-associated myelopathy. RESULTS:Three patients (2 females and 1 male) had long-standing DM1 and developed progressive myelopathy in their early 40's. All were found to have thoracic SEL (extensive extradural T1, T2 hyperintense signal; biopsy confirmed in one case) with associated extensive abnormal cord signal in lower cervical/upper thoracic spinal cord. A comprehensive evaluation for metabolic, infectious, autoimmune and vascular causes of myelopathy that included serologies, cerebrospinal fluid analyses, and spinal angiography did not reveal an alternative cause for myelopathy. One of the patients underwent a surgical decompression of SEL with subsequent clinical and radiologic improvement. CONCLUSIONS:Our case series suggest that patients with DM1 and myelopathy of unknown cause should be evaluated for SEL. Timely diagnosis and appropriate intervention may forestall progression of neurological disability and even result in neurologic improvement. SEL should be considered on the short list of diagnoses that cause potentially reversible progressive myelopathy.

BACKGROUND AND PURPOSE/OBJECTIVE:Conventional imaging frequently shows overlapping features between benign and malignant parotid neoplasms. We investigated dynamic contrast-enhanced MR imaging using golden-angle radial sparse parallel imaging in differentiating parotid neoplasms. MATERIALS AND METHODS/METHODS:= 32) combined semiquantitative time-intensity curve metrics with ADC values. RESULTS:< .001). CONCLUSIONS:Golden-angle radial sparse parallel MR imaging allows high spatial and temporal resolution permeability characterization of parotid neoplasms, with a high negative predictive value for malignancy prediction. Combining time-to-maximum and ADC improves pleomorphic adenoma prediction compared with either metric alone.

Cavernous sinuses are paired interconnected venous plexuses situated in the floor of the middle cranial fossa on either side of the sella turcica and sphenoid sinus. They are lined by dura mater and consist of multiple venous channels within. The cavernous sinuses are intimately related to the internal carotid artery and its associated sympathetic plexus, the oculomotor nerve, the trochlear nerve, the abducens nerve, and the ophthalmic nerve. Cavernous sinuses are connected to the orbit, the pterygopalatine fossa, the infratemporal fossa, the nasopharynx, and the posterior cranial fossa by various foramina, fissures, and canals in the skull base. A multitude of structures in close relation to the cavernous sinus give rise to a myriad of possible pathologic conditions that can be broadly classified into (a) neoplastic, (b) vascular, (c) infective or inflammatory, or (d) miscellaneous lesions. These pathologic conditions can have overlapping clinical manifestations. Hence, imaging plays a crucial role in identifying the disease, assessing its extent, providing a pertinent differential diagnosis to guide further management, and suggesting a site or route for biopsy. MRI is the modality of choice to depict the cavernous sinuses, with CT and digital subtraction angiography playing supplementary roles in certain situations. In this article, the cavernous sinus lesions encountered in our institution during a 10-year period are reviewed. The purpose of the article is to (a) describe the anatomy of the cavernous sinus; (b) demonstrate the multimodality imaging spectrum of a wide variety of pathologic conditions involving the cavernous sinus, correlating with the histopathologic findings; (c) highlight important imaging clues for differential diagnosis; and (d) help the reader overcome potential pitfalls in interpretation. Online supplemental material is available for this article. ^©RSNA, 2019.

OBJECTIVE:Machine learning has recently gained considerable attention because of promising results for a wide range of radiology applications. Here we review recent work using machine learning in brain tumor imaging, specifically segmentation and MRI radiomics of gliomas. CONCLUSION/CONCLUSIONS:We discuss available resources, state-of-the-art segmentation methods, and machine learning radiomics for glioma. We highlight the challenges of these techniques as well as the future potential in clinical diagnostics, prognostics, and decision making.

Background/UNASSIGNED:While effective for the repair of large skull base defects, the Hadad-Bassagasteguy nasoseptal flap increases operative time and can result in a several-week period of postoperative crusting during re-mucosalization of the denuded nasal septum. Endoscopic transsphenoidal surgery for pituitary adenoma resection is generally not associated with large dural defects and high-flow cerebrospinal fluid (CSF) leaks requiring extensive reconstruction. Here, we present the posterior nasoseptal flap as a novel technique for closure of skull defects following endoscopic resection of pituitary adenomas. This flap is raised in all surgeries during the transnasal exposure using septal mucoperiosteum that would otherwise be discarded during the posterior septectomy performed in binostril approaches. Methods/UNASSIGNED:We present a retrospective, consecutive case series of 43 patients undergoing endoscopic transsphenoidal resection of a pituitary adenoma followed by posterior nasoseptal flap placement and closure. Main outcome measures were extent of resection and postoperative CSF leak. Results/UNASSIGNED:The mean extent of resection was 97.16 ± 1.03%. Radiographic measurement showed flap length to be adequate. While a defect in the diaphragma sellae and CSF leak were identified in 21 patients during surgery, postoperative CSF leak occurred in only one patient. Conclusions/UNASSIGNED:The posterior nasoseptal flap provides adequate coverage of the surgical defect and is nearly always successful in preventing postoperative CSF leak following endoscopic transsphenoidal resection of pituitary adenomas. The flap is raised from mucoperiosteum lining the posterior nasal septum, which is otherwise resected during posterior septectomy. Because the anterior septal cartilage is not denuded, raising such flaps avoids the postoperative morbidity associated with the larger Hadad-Bassagasteguy nasoseptal flap.

Background: Assessment of preoperative imaging is important for operative planning of meningioma resection. A hyperintense rim on T2-weighted (T2W) MRI is frequently thought to represent a CSF cleft between the tumor and the brain, suggesting a clean arachnoid plane. However, brain invasion (loss of arachnoid plane) is often encountered instead. We sought to further characterize this radiographic finding and identify correlates with intraoperative brain invasion and pathology in patients undergoing meningioma resection. Methods: Retrospective review of 42 patients (mean age: 54.2 years, SD: 13.0, 76% female) who underwent meningioma resection between 2013 and 2016 at a single institution. Demographic variables and pathology results were recorded. Radiographic variables on preoperative MRI included presence and size of a hyperintense rim on T2W MRI, a contrast-enhancing rim on fluid-attenuated inversion recovery (FLAIR), and adjacent edema. Operative reports were reviewed for identification of loss of arachnoid plane (brain invasion) noted during surgery. Radiographic findings were then correlated with brain invasion using nonparametric statistics. Results: Of 42 meningiomas resected, there were 29 (69%) WHO Grade I, 12 (29%) WHO Grade II, and 1 (2%) WHO Grade III. Twenty-three tumors (55%) were located at the skull base. On preoperative T2WI, 36 (86%) of meningiomas demonstrated a hyperintense cleft with a mean width of 2.86 mm (SD: 1.66) and 16 had adjacent edema. Twenty-six meningiomas demonstrated a contrast-enhancing rim on FLAIR with a mean width of 2.85 mm (SD: 1.06) and 28 meningiomas exhibited a rim that was both T2 hyperintense and enhancing on FLAIR. Intraoperatively, 24 (57%) of meningiomas were found to have partial or complete loss of an arachnoid plane between the tumor and adjacent brain parenchyma. Both a hyperintense T2 cleft and enhancing FLAIR rim were associated with loss of arachnoid plane (p=0.004 for T2, <0.001 for FLAIR, <0.001 for combined). Conclusion: Preoperative MRI of meningiomas often identifies a T2 hyperintense rim frequently thought to represent a CSF cleft. A correlation with enhancement on FLAIR and intraoperative loss of arachnoid plane suggests this may be a useful marker of brain invasion and could aid in operative planning and risk assessment

BACKGROUND:Hearing preservation is a goal for many patients with vestibular schwannoma. We examined pretreatment magnetic resonance imaging (MRI) and posttreatment hearing outcome after stereotactic radiosurgery. METHODS:From 2004 to 2014, a cohort of 125 consecutive patients with vestibular schwannoma (VS) treated via stereotactic radiosurgery (SRS) were retrospectively reviewed. MRIs containing three-dimensional constructive interference in steady state or equivalent within 1 year before treatment were classified by two radiologists for pretreatment characteristics. "Good" hearing was defined as American Academy of Otolaryngology-Head and Neck Surgery class A. Poor hearing outcome was defined as loss of good pretreatment hearing after stereotactic radiosurgery. RESULTS:Sixty-one patients met criteria for inclusion. Most had tumors in the distal internal auditory canal (55%), separated from the brainstem (63%), oval shape (64%) without cysts (86%), and median volume of 0.85 ± 0.55 cm. Pretreatment audiograms were performed a median of 108 ± 173 days before stereotactic radiosurgery; 38% had good pretreatment hearing. Smaller tumor volume (p < 0.005) was the only variable associated with good pretreatment hearing. 49 (80%) patients had posttreatment audiometry, with median follow-up of 197 ± 247 days. Asymmetrically decreased pretreatment cochlear CISS signal on the side of the VS was the only variable associated with poor hearing outcome (p = 0.001). Inter-rater agreement on cochlear three-dimensional constructive interference in steady state preservation was 91%. CONCLUSIONS:Decreased cochlear CISS signal may indicate a tumor's association with the cochlear neurovascular bundle, influencing endolymph protein concentration and creating an inability to preserve hearing. This important MRI characteristic can influence planning, counseling, and patient selection for vestibular schwannoma treatment.

Dynamic contrast-enhanced (DCE) MR imaging uses rapid sequential MR image acquisition before, during, and after intravenous contrast administration to elucidate information on the microvascular biologic function of tissues. The derived pharmacokinetic parameters provide useful information on tissue perfusion and permeability that may help to evaluate entities that otherwise appear similar by conventional imaging. When specifically applied to the evaluation of head and neck cancer, DCE-MR imaging may provide valuable information to help predict treatment response, discriminate between posttreatment changes and residual tumor, and discriminate between various head and neck neoplasms.