MRI-suspected low-grade glioma: is there a need to perform dynamic FET PET?

Abstract

Among the MRI-suspected LGG, kinetic but not conventional analysis of FET uptake enabled remarkably high sensitivity for detection of HGG. This held true even for lesions with low or diffuse tracer uptake. Lesions with reduced tracer uptake must be interpreted with caution, as they can also harbour HGG tissue.

Dynamic 18F‐FET PET in suspected WHO grade II gliomas defines distinct biological subgroups with different clinical courses

“…10 With respect to differentiation between lowand high-grade histology, it has been become clear, however, that conventional analyses of 18 F-FET PET with determination of static values such as the ratio of maximal 18 F-FET uptake within the tumor as compared to the background (SUV max /BG) lack specificity and sensitivity; this is explained by the marked overlap of the distributions of the uptake ratios in low-and high-grade tumors. 11 In contrast, dynamic analysis of 18 F-FET uptake over a period of 40 min has been shown to enable noninvasive tumor grading with high diagnostic power 12,13 : "Increasing" time-activity curves (TAC) of 18 F-FET uptake, with standard uptake values (SUV) constantly ascending or reaching a peak followed by a plateau has been demonstrated to indicate low-grade histology. "Decreasing" TAC, with SUVs exhibiting an early peak followed by a constant descend, correlate with a high-grade phenotype.…”

Diagnostic accuracy of F-18-fluoroethyltyrosine PET and PET/CT in patients with brain tumor

“…1 Flowchart of study identification and selection. *Note: Among these, a subpopulation of n = 14 studies with N = 525 patients did report target-to-background ratio (TBR) data, which were used for deriving TBR thresholds yielding the best diagnostic performances method [26], or (5) a fixed 25-mm 2 elliptic ROI centered on the area of most increased FET uptake [27,28]. In three studies, the method used to define the ROI was not specified [29][30][31].…”

“…Sixteen studies [8,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] with a total of N = 641 patients (Table 1) were eligible for inclusion in the present metaanalysis. Six studies had mixed populations with both primary brain tumor and recurrence (#1, 9, 11, 12, 13, and 14, Table 1) and one did not report histology results for all patients (#2, Table 1).…”

“…Quantitative tumor-to-background ratio (TBR) threshold for diagnosing brain tumor and glioma Individual patient meanTBR results were given in n = 9 studies (N = 271 patients) [18-22, 27-29, 31]) and max-TBR in n = 7 studies (N = 329 patients) [8,19,20,[24][25][26]30]. The ROC curve analysis indicated that meanTBR C1.6 For over a decade, FET-PET has been known to help in distinguishing between proliferating tumoral and nontumoral lesions [5,10].…”

“…Similarly, for gliomas, a meanTBR C1.7 and a maxTBR C2.2 demonstrated excellent diagnostic performances, with significantly lower meanTBR and maxTBR in low-grade than in high-grade gliomas. On dynamic acquisitions, several studies [8,23,26,39] reported accurate distinction between low-grade and high-grade untreated gliomas using information from tumor time-activity curves, such as an increasing/decreasing slope uptake pattern [26,39] or early-to-middle uptake ratio [23]. Whether combining conventional MRI with MRS, diffusion imaging and dynamic FET-PET imaging could provide better performances for diagnosing glioma that has not been established in large populations [40,41].…”