Prospective Study to Evaluate the Role of Dual Point Contrast-enhanced Magnetic Resonance Imaging in Differentiation of Brain Tumoral from Nontumoral Tissue: A Magnetic Resonance/PET Study

Abstract

Background and purpose: Follow-up imaging of gliomas is crucial to look for residual or recurrence and to differentiate them from nontumoral tissue. Positron emission tomography (PET)-magnetic resonance imaging (MRI) is the problem-solving tool in such cases. We investigated the role of dual point contrast (DPC)-enhanced MRI to discriminate tumoral from the nontumoral tissue compared to PET-MRI taken as the gold standard.

Materials and methods: The institutional ethics committee approved the study, and consent was obtained from all the patients included in the study. We prospectively did immediate and 75-min delayed contrast MRI in glioma cases who came for follow-up as a part of PET-MRI study in our institute. Subtracted images were obtained using immediate and 75-min delayed contrast images. Color-coded subtracted images were compared with PET-MRI images. 75-min delayed contrast MRI and diffusion-weighted imaging (DWI) images with Gray Scale inversion were compared with PET attenuation-corrected images.

Results: We included 23 PET MRI cases done with different radiotracers in our study. Overall, we found PET-DPC correlation in (20/20 ~ 100%) cases of enhancing tumors. In two cases (DOPA and fluorodeoxyglucose), since they were nonenhancing low-grade gliomas and the other one was melanoma with intrinsic T1 hyperintensity and the DPC technique could not be used. DWI-PET correlated in 17/19 (~89.4%) cases, and perfusion-weighted imaging (PWI)-PET dynamic susceptibility contrast (DSC)/ASL correlated in 14/18 (~77.7%) cases after cases with hemorrhage were excluded.

Conclusion: DPC MRI showed a good correlation with PET MRI in discriminating tumoral from the nontumoral tissue. DPC MRI can act as a potential alternative to PET MRI in peripheral hospitals where PET is not available. However, the DPC technique is limited in low-grade nonenhancing gliomas.

Keywords: Brain tumors; dual point contrast magnetic resonance imaging; positron emission tomography.

Figure 1

Case of cerebral metastases in primary lung malignancy shows increased marginal uptake in right frontal lobe lesion (red arrow) in ¹⁸F-fluorodeoxyglucose(FDG) PET-AC(attenuation corrected) (a) and color-coded positron emission tomography images (e), peripheral enhancement (b) and washout in 75-min delayed postcontrast (c), marginal diffusion restriction (d) and marginal enhancement in subtracted T1 contrast image (f)

Figure 2

Operated case of glioblastoma multiforme, isocitrate dehydrogenase (IDH) wild type with recurrence (orange arrows), shows increased marginal uptake around the postoperative cavity in left frontal and occipital lobes in C11-methionine PET-AC (attenuation corrected) (a) and color-coded positron emission tomography images (e), peripheral enhancement (b) and washout in 75-min delayed T1 contrast (c), marginal diffusion restriction (d), around postoperative cavity with peripheral enhancement seen in subtracted T1 contrast image (f)

Figure 3

Operated case of anaplastic astrocytoma (World Health Organization grade III, isocitrate dehydrogenase1 (IDH1) negative, not otherwise specified (NOS) with recurrence (red arrows) shows peripheral rim of hypermetabolic lesions (¹⁸F-fluoroethyl-L-tyrosine positron emission tomography AC (a) and color-coded positron emission tomography images (e) in septum pellucidum, splenium of the corpus callosum, left parieto-occipital lobes. There is peripheral rim enhancement (b) with washout in 75 min delayed contrast images (c), corresponding marginal diffusion restriction (d) and contrast rim enhancement in the subtracted T1 contrast images (f)

Figure 4

Operated case of glioblastoma multiforme, isocitrate dehydrogenase (IDH) wild type with recurrence (green arrows), shows uptake in the left occipital lobe in ¹⁸F-dihydroxyphenylalanine(DOPA) PET-AC(attenuation corrected) (a) and color-coded positron emission tomography images (e), enhancement (b) and washout in 75-min delayed T1 contrast (c), enhancement in subtracted T1 contrast image (f), no diffusion restriction (d) due to areas of hemorrhage. Adjacent postoperative collection (asterisk) with no metabolic uptake and no enhancement seen in the left occipital region

Figure 5

Case of diffuse astrocytoma, World Health Organization grade II, status post (s/p) surgical resection shows postoperative cavity with no recurrence (asterisk). There is no diffusion-weighted imaging restriction (d), no enhancing lesion on immediate, 75 min delayed and subtracted contrast images (b, c and f) and no metabolic uptake on C11-methionine PET-AC(attenuation corrected) (a) and color-coded positron emission tomography (e)

Figure 6

Case of anaplastic Oligodendroglioma (ODG), Isocitrate dehydrogenase (IDH) mutant, 1p/19q co-deleted, World Health Organization grade III, postoperative and postchemoradiotherapy with radiation necrosis (asterisk) and recurrence (red arrows) along the periphery. There is peripheral rim enhancement (b) with progressive contrast filling in seen on 75-min delayed contrast images (c) and central areas of diffusion restriction (d) in the left frontal lobe and genu of corpus callosum consistent with radiation necrosis. There is central ametabolism and peripheral rim of hypermetabolism seen on C11-methionine PET-AC (attenuation corrected) (a) and color-coded positron emission tomography images (e) and peripheral rim of enhancement in subtracted T1 contrast images (f) suggestive of recurrence with central necrosis

Figure 7

Case of pleomorphic xanthoastrocytoma shows a solid cystic lesion in the right anterior temporal lobe with peripheral rim of enhancement (b) and incomplete washout in 75-min delayed contrast image (c) and no diffusion restriction (d). Focal peripheral hypermetabolism seen in the anterior aspect of the lesion on ¹⁸F-fluorodeoxyglucose(FDG) PET-AC(attenuation corrected) (a) and color-coded positron emission tomography images (e) with peripheral enhancement in subtracted T1 contrast images (f)

Figure 8

Case of diffuse astrocytoma, not otherwise specified (NOS), isocitrate dehydrogenase1 (IDH1) negative, World Health Organization grade 2, Ponto medullary region, postradiotherapy. There are patchy hypermetabolic areas (black arrow) in the pons on ¹⁸F-dihydroxyphenylalanine(DOPA) PET-AC(attenuation corrected) (a) and color-coded positron emission tomography images (e) with few areas of diffusion restriction (d: red arrow) and no enhancement in immediate (b) and 75-min delayed contrast images (c) and subtracted T1 contrast images (f)

Figure 9

Case of cerebellar melanoma, postoperative and postradiotherapy with residual lesion shows focal hypermetabolic lesion (black arrow) in the right middle cerebellar peduncle on ¹⁸F-fluorodeoxyglucose(FDG) PET-AC(attenuation corrected) (a) and color-coded positron emission tomography images (e) with patchy enhancement on subtracted T1 contrast (f) and no diffusion restriction (d). Immediate contrast (b) and 75-min delayed contrast images (c) are not helpful due to the intrinsic hyperintense nature of the melanoma