. 2021 Jun 11;11(6):775. doi: 10.3390/brainsci11060775

Table 1.

Summary of the included studies.

First Author, Year	Study Design	Number of Patients (E/C)	Parameters for Analysis	Summary of the Outcome
Winter, 2015 [12]	Single-arm prospective study	14 (7 mild, 4 moderate, and 3 severe TBI)	$K^{T r a n s}$	Although there was no statistical significance, as TBI severity became more severe, the $K^{T r a n s}$ value increased. $K^{T r a n s}$ value was significantly correlated with the SPECT findings.
Yoo, 2019 [14]	Retrospective study	44 (mild TBI)/32	$K^{T r a n s}$ , $v_{e}$	$K^{T r a n s}$ and $v_{e}$ values at dorsolateral midbrain and $K^{T r a n s}$ at bilateral frontal gray-white matter were significantly higher in the TBI patients. Delayed recall scores were significantly correlated with $v_{e}$ values.
O’Keeffe, 2020 [11]	Single-arm prospective study	5 professional MMA fighters and 19 adolescent rugby players	Slope of contrast agent concentration	MMA fighters: the degree of BBB disruption was correlated with the duration and repeatability of the strike. Rugby players: BBB disruption was found in the periventricular regions.
Yoen, 2021 [13]	Retrospective study	42 (mild TBI)/29	$K^{T r a n s}$ , $v_{p}$	$The K^{T r a n s}$ value in the bilateral cerebral cortex was significantly higher in mild TBI patients. $v_{p}$ values in the bilateral cerebellar white matter and brainstem were significantly lower in mild TBI patients.

E, experimental group; C, control group; TBI, traumatic brain injury; SPECT, single-photon emission computed tomography; BBB, blood brain barrier; MMA, mixed martial arts; $K^{T r a n s}$ , volume transfer constant; $v_{e}$ , extravascular extracellular space volume fraction; $v_{p}$ , blood plasma volume fraction.