Use of Contrast‐Enhanced Fluid‐Attenuated Inversion Recovery Sequence to Detect Brain Lesions in Dogs and Cats

Abstract

BackgroundThe diagnostic value of a contrast‐enhanced T2‐weighted FLAIR sequence (ceFLAIR) in brain imaging is unclear.Hypothesis/ObjectivesThat the number of brain lesions detected with ceFLAIR would be no greater than the sum of lesions detected with nFLAIR and ceT1W sequence.AnimalsOne hundred and twenty‐nine animals (108 dogs and 21 cats) undergoing magnetic resonance imaging (MRI) of the head between July 2010 and October 2011 were included in the study.MethodsA transverse ceFLAIR was added to a standard brain MRI protocol. Presence and number of lesions were determined based on all available MRI sequences by 3 examiners in consensus and lesion visibility was evaluated for nFLAIR, ceFLAIR, and ceT1W sequences.ResultsEighty‐three lesions (58 intra‐axial and 25 extra‐axial) were identified in 51 patients. Five lesions were detected with nFLAIR alone, 2 with ceT1W alone, and 1 with ceFLAIR alone. Significantly higher numbers of lesions were detected using ceFLAIR than nFLAIR (76 versus 67 lesions; P = 0.04), in particular for lesions also detected with ceT1W images (53 versus 40; P =.01). There was no significant difference between the number of lesions detected with combined nFLAIR and ceT1W sequences compared to those detected with ceFLAIR (82 versus 76; P =.25).Conclusion and Clinical ImportanceUse of ceFLAIR as a complementary sequence to nFLAIR and ceT1W sequences did not improve the detection of brain lesions and cannot be recommended as part of a routine brain MRI protocol in dogs and cats with suspected brain lesions.

Abrogation of fluid suppression in intracranial postcontrast fluid‐attenuated inversion recovery magnetic resonance imaging: A clinical and phantom study

“…Previous veterinary studies, and many human studies do not provide correlative T2 weighted imaging data, although Kubota et al . correlated level of T2 signal with postcontrast‐T2 FLAIR lesions, and similar to our findings, Merhof et al . noted that “new” lesions were visible on T2 weighted images.…”

“…Kubota et al21 correlated level of T2 signal with postcontrast-T2 FLAIR lesions, and similar to our findings, Merhof et al1 noted that "new" lesions were visible on T2 weighted images. The discrepancy between pre-and postcontrast FLAIR images noted in one veterinary study 1 are also compatible with the reappearance of previously nulled fluid signal.…”

“…noted that “new” lesions were visible on T2 weighted images. The discrepancy between pre‐ and postcontrast FLAIR images noted in one veterinary study are also compatible with the reappearance of previously nulled fluid signal.…”

“…FLAIR has been variably reported in both veterinary, 1,2 and human studies, [3][4][5] with its use in meningeal based disease commonly reported as beneficial. [6][7][8] The mechanism for increased signal intensity on postcontrast-T2 FLAIR images is variably reported and includes mild T1 effects (in the heavily T2 weighted images), increased T1 contrast due to the use of inversion recovery sequences, magnetization transfer effects, and delayed enhancement.…”

“…Postcontrast T2 FLAIR imaging sequences have been investigated in a variety of intracranial pathologies with the goal of increasing diagnostic sensitivity. The diagnostic value of postcontrast‐T2 FLAIR has been variably reported in both veterinary, and human studies, with its use in meningeal based disease commonly reported as beneficial . The mechanism for increased signal intensity on postcontrast‐T2 FLAIR images is variably reported and includes mild T1 effects (in the heavily T2 weighted images), increased T1 contrast due to the use of inversion recovery sequences, magnetization transfer effects, and delayed enhancement .…”