Abstract
BackgroundT1 inversion recovery (T1IR) sequence improved tissue contrast by providing higher gray matter-white matter contrast ratio (GM-WM contrast ratio) and higher lesion contrast noise ratio (CNR). This study aims to highlight its significance in the evaluation of space-occupying lesions whether intra-axial or extra-axial and also in multiple sclerosis (MS) by comparing it with T1 spin echo (T1SE) sequence.ResultIn a total of 50 patients, 14 patients with extra-axial lesions, 18 patients with intra-axial lesions, and 18 patients with multiple sclerosis were included. The CNR was significantly higher for pre-contrast T1IR images than for pre-contrast T1SE (− 13.04 (1.20) vs − 7.73 (0.70); p value < 0.01). After giving intravenous contrast media, CNR in T1SE was higher than T1IR (11.14 (1.75) vs 9.41 (1.83)) without statistical significance (p value = 0.19) and CNR was higher in T1IR than T1SE in lesions with low enhancement ratio (ER). As well, the overall number of lesions was higher on T1IR especially in MS (10.67 (2.26) vs 3.89 (1.05); p value < 0.01).ConclusionOn pre-contrast sequences, T1IR could be used as an added sequence in most brain lesions giving higher lesion CNR. After giving intravenous contrast media, T1IR could be used in lesions with low ER. It also could be used in situations in which gadolinium injection is contraindicated and also could be used in follow-up of MS patient by detecting a higher number of lesions that can be easily missed in T1SE.
Highlights
T1 inversion recovery (T1IR) sequence improved tissue contrast by providing higher gray matterwhite matter contrast ratio (GM-WM contrast ratio) and higher lesion contrast noise ratio (CNR)
Subgroup analysis Comparing T1 spin echo (T1SE) and T1IR based on type of lesion The CNR was significantly higher in T1IR before contrast injection at all types of lesions either extra-axial, intra-axial, or multiple sclerosis (MS) with mean values − 13.90 (2.86), − 12.87 (2.40), and − 12.69 (1.63) and with p values 0.02, < 0.05, and 0.01, respectively (Figs. 2, 3, and 4)
We found that T1IR was statistically significant in MS group as regards to the number of lesions (10.67 (2.26) vs 3.89 (1.05); p value < 0.01; Fig. 4), but it showed no difference in extra- or intra-axial lesions with mean values 1.29 (0.16) vs 1.29 (0.16) (p value = 0.5) and 2.19 (0.94) vs 1.75 (0.57) (p value 0.13; Table 4)
Summary
T1 inversion recovery (T1IR) sequence improved tissue contrast by providing higher gray matterwhite matter contrast ratio (GM-WM contrast ratio) and higher lesion contrast noise ratio (CNR). Through reducing the acquisition time in this sequence and increasing its spatial resolution by applying multishot echo planar imaging and fast spin echo imaging, it became practical to be used in neuroimaging [2]. It improved tissue contrast by providing higher gray matter-white matter (GM-WM) contrast. It could be used in the diagnosis, monitoring disease progression, and treatment efficacy in multiple sclerosis (MS) as it detects the black hole lesions that show better correlation with clinical disability [4]. T1IR, by providing higher GM-WM contrast ratio and lesion CNR, might aid in revealing a higher number of cortical lesions in MS that go undetected in conventional MR
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