High‐field MRI using standard pulse sequences has moderate to substantial interobserver agreement and good accuracy for differentiation between intracranial extra‐axial histiocytic sarcoma and meningioma in dogs

Abstract

Intracranial extra‐axial histiocytic sarcoma shares common MRI features with meningioma. As histiocytic sarcoma carries a generally worse prognosis than meningioma, the ability to differentiate between these two neoplasms is of clinical value. The aim of this retrospective diagnostic accuracy and observer agreement study was to evaluate the accuracy and reliability of high‐field MRI to differentiate between these two tumors, using standard pulse sequences and published MRI features. A total of 51 dogs were included (26 meningiomas and 25 histiocytic sarcomas). Magnetic resonance imaging examinations were independently assessed by three experienced board‐certified radiologists, evaluating 18 imaging features. They were asked to assign each case to one of three categories (meningioma, histiocytic sarcoma, and undetermined). Agreement for the MRI diagnosis across all three reviewers was moderate (κ 0.54) while paired interobserver agreement ranged from moderate to substantial (κ 0.58‐0.74) with percent agreement ranging between 86.1% and 87.7%. Overall, the probability of correctly diagnosing meningioma in a dog with this tumor ranged between 79.2% and 94.4%, and the probability of correctly diagnosing histiocytic sarcoma in a dog with this tumor ranged between 76.0% and 92.3%. The overall probability to diagnose the correct tumor, irrespective of type, ranged between 79.2% and 89.7%. Histiocytic sarcomas tended to have more extensive edema and more often had combined perilesional and distant meningeal enhancement affecting both pachy‐ and leptomeninges, while for meningiomas, meningeal enhancement tended to more commonly be perilesional and pachymeningeal. Imaging features that seemed more useful to make a correct diagnosis included “location/type of meningeal enhancement,” “osseous changes in the adjacent neurocranium,” “cystic changes,” and “herniation severity.”

An Illustrated Scoping Review of the Magnetic Resonance Imaging Characteristics of Canine and Feline Brain Tumors

“…After the exclusion of studies describing experimentally induced brain tumors and other irrelevant records, de-duplication of records appearing repeatedly in our database searches using the different MeSH search phrases, and removal of studies that contained <3 cases, unconfirmed diagnoses, or limited MRI data, we identified 67 articles (Figure 1) that fulfilled the inclusion criteria, with these studies reporting a total of 1630 canine (from 59 studies) and 125 feline cases (from 9 studies) with tumors [2,[6][7][8][9][10][11][12][13]25,26,. A total of 62/67 studies were classified using Oxford hierarchal evidentiary criteria [27]: 45/62 (73%) were level 2b retrospective cohort studies [2,[6][7][8][9][10][11]25,26,29,[31][32][33][35][36][37][40][41][42]48,[51][52][53][54][55][56][57][58][59][63][64][65]…”

“…Meningiomas are also the primary diagnostic consideration for extra-axial meningealbased lesions that contain large solitary or multifocal cysts (Figure 3, Cases 7-9), which appear as well-demarcated T1W hypointense, T2W hyperintense, non-enhancing spherical to multiloculated regions [47,48]. Cystic meningiomas have comprised 13-32% of canine meningiomas included in the studies in this review [2,7,10,[30][31][32]40,48,[52][53][54], although an additional subset of meningiomas also contain smaller foci of intratumoral cysts/fluid or intratumoral hemorrhage, with hemorrhage appearing as conspicuous signal voids or susceptibility artifacts on T2*GRE or SWI [9,14,48,54].…”

“…Canine meningiomas have also been shown to cause displacement of local blood vessels in three dimensional time-of-flight magnetic resonance angiographic (3D TOF MRA) studies [53]. Meningiomas are also the most likely extra-axial, meningeal-based tumors to cause secondary changes in the skull adjacent to the tumor [9,40,52]. Bony changes most often consist of thickening and sclerosis of the calvarium (calvarial hyperostosis) but can also rarely include lysis [2,9,40,52].…”

“…Meningiomas are also the most likely extra-axial, meningeal-based tumors to cause secondary changes in the skull adjacent to the tumor [9,40,52]. Bony changes most often consist of thickening and sclerosis of the calvarium (calvarial hyperostosis) but can also rarely include lysis [2,9,40,52]. Calvarial hyperostosis (Table 1; Figure 3, Case 1) is observed much more frequently in feline meningiomas [9,40,52].…”

Intracranial Granular Cell Tumours in Three Dogs: Atypical Magnetic Resonance Imaging Features and Immunohistochemical Study

“…Meningiomas are extra-axial neoplasms of typical supratentorial location that most commonly affect the fronto-olfactory region [ 8 , 18 , 19 ], although they can arise from any meningeal source. They are typically round-to-ovoid tumours or they can less frequently present as plaquelike masses with a broad-based contact with the underlying bone [ 19 , 20 , 21 ]. However, plaquelike meningiomas accounted for less than 30% of cases in one study [ 22 ] and were all restricted to basilar and parasellar locations.…”