Table 1. Included studies with the clinical condition of focus, population size, details about scanner manufacturer, acquisition method and ADC calculation.
| Study id | Study (Ref. no.) | Clinical condition | Population size | Scanner manufacturer | Acquisition method | ADC calculation |
|---|---|---|---|---|---|---|
| 1 | Kato et al., 2008 (34) | Parotid gland tumor | 4 | Philips | EPI, FS NI | Mono-exponential |
| 2 | Wang et al., 2014 (35) | Kimura disease | 5 | Siemens | EPI, FS NI | Mono-exponential |
| 3 | Terra et al., 2017 (36) | Other parotid glands diseases, healthy parotid glands | 7 | GE | EPI, FS NI | Mono-exponential |
| 4 | Doornaert et al., 2015 (37) | Irradiated normal parotid parenchyma | 8 | Siemens | EPI + HASTE (SS-TSE), FS NI | Mono-exponential |
| 5 | Dirix et al., 2008 (38) | Irradiated normal parotid parenchyma | 8 | Siemens | EPI, FS NI | Mono-exponential |
| 6 | Thoeny et al., 2004 (8) | Normal parotid parenchyma | 8 | Siemens | EPI, FS NI | Mono-exponential |
| 7 | Juan et al., 2015 (10) | Irradiated normal parotid parenchyma | 11 | GE | EPI, FS NI | Mono-exponential |
| 8 | Thoeny et al., 2005 (39) | Normal parotid parenchyma | 12 | Siemens | EPI, FS NI | Mono-exponential |
| 9 | Liu et al., 2015 (40) | Irradiated normal parotid parenchyma, normal parotid parenchyma | 13 | GE | EPI, FS NI | Mono-exponential |
| 10 | Zhou et al., 2016 (41) | Irradiated normal parotid parenchyma | 18 | Philips | SS-EPI, SPAIR | IVIM, Bi-exponential |
| 11 | Louimu et al., 2017 (5) | Irradiated normal parotid parenchyma | 20 | GE | EPI, FS NI | Mono-exponential |
| 12 | Kato et al., 2011 (42) | Other parotid glands diseases, normal parotid parenchyma | 20 | Philips | EPI, STIR | Mono-exponential |
| 13 | Zhang et al., 2001 (4) | Irradiated normal parotid parenchyma | 21 | GE | EPI, FS NI | Mono-exponential b-values below 150 s/mm2 |
| 14 | Zhang et al., 2018a (6) | Irradiated normal parotid parenchyma | 23 | GE | EPI, FS NI | Mono-exponential |
| 15 | Habermann et al., 2007 (43) | Normal parotid parenchyma | 27 | Siemens | EPI, SPIR | Mono-exponential |
| 16 | Zhang et al., 2013 (44) | Irradiated normal parotid parenchyma | 28 | GE | EPI, FS NI | Mono-exponential |
| 17 | Zhou et al., 2017 (45) | Irradiated normal parotid parenchyma | 28 | Philips | SS-TSE, FS NI | Mono-exponential |
| 18 | Yoshino et al., 2001 (46) | Other parotid glands diseases, normal parotid parenchyma | 28 | Siemens | EPI, SPIR | Mono-exponential |
| 19 | Sumi et al., 2012 (47) | Parotid gland tumor | 31 | Philips | EPI, FS NI | IVIM, Mono-exponential |
| 20 | Xu et al., 2017 (9) | Sjögren's syndrome, normal parotid parenchyma | 31 | Siemens | EPI, FS NI | Mono-exponential |
| 21 | Zhou et al., 2018 (48) | Irradiated normal parotid parenchyma | 32 | Philips | EPI, FS SPAIR | DKI, Mono-exponential |
| 22 | Matsushima et al., 2007 (49) | Parotid gland tumor | 32 | NI | EPI, FS NI | Mono-exponential |
| 23 | Juan et al., 2009 (50) | Normal parotid parenchyma | 33 | GE | EPI, both FS and no-FS, NI | Mono-exponential |
| 24 | Marzi et al., 2015 (51) | Irradiated normal parotid parenchyma | 34 | GE | EPI, FS NI | IVIM, Mono-exponential |
| 25 | Zhang et al., 2018b (52) | Parotid gland tumor | 36 | Siemens | EPI, FS NI | Mono-exponential |
| 26 | Matsusue et al., 2017 (53) | Parotid gland tumor | 36 | GE | EPI, FS NI | Mono-exponential |
| 27 | Ikeda et al., 2004 (54) | Parotid gland tumor | 36 | GE | EPI, FS NI | Mono-exponential |
| 28 | Fruehwald-Pallamar et al., 2013 (55) | Parotid gland tumor | 38 | Philips | EPI, FS NI | Mono-exponential |
| 29 | Eida et al., 2007 (56) | Parotid gland tumor, normal parotid parenchyma | 41 | Philips | EPI, FS NI | Mono-exponential |
| 30 | Kato et al., 2017 (57) | Parotid gland tumor | 45 | Philips | EPI, FS STIR | Mono-exponential |
| 31 | Milad et al., 2017 (58) | Parotid gland tumor | 46 | Philips | EPI, FS NI | Mono-exponential |
| 32 | Motoori et al., 2004 (59) | Other parotid glands diseases, parotid gland tumor | 46 | GE | EPI, FS NI | Mono-exponential |
| 33 | Yabuuchi et al., 2008 (60) | |||||
| 34 | Zhang et al., 2018c (61) | Parotid gland tumor | 47 | Siemens | EPI, FS NI | Mono-exponential |
| 35 | Sumi et al., 2002 (62) | Parotid gland tumor | 51 | Siemens | EPI, FS NI | Mono-exponential |
| 36 | Ma et al., 2018 (63) | Sjögren's syndrome, other parotid glands diseases, normal parotid parenchyma | 58 | GE | EPI, FS NI | Mono-exponential |
| 37 | Regier et al., 2009 (64) | Parotid gland tumor | 60 | Siemens | EPI, FS NI | Mono-exponential |
| 38 | Sun et al., 2019 (65) | Sjögren's syndrome, normal parotid parenchyma | 65 | Siemens | EPI, FS NI | Mono-exponential |
| 39 | Ries et al., 2008 (66) | Parotid gland tumor, normal parotid parenchyma | 65 | Philips | EPI, TSS, FS NI | Mono-exponential |
| 40 | Celebi et al., 2013 (67) | Other parotid glands diseases, normal parotid parenchyma | 71 | Siemens | EPI, FS SPIR | Mono-exponential |
| 41 | Wang et al., 2001 (68) | Other parotid glands diseases | 75 | GE | EPI, FS STIR | Mono-exponential |
| 42 | Chang et al., 2014 (69) | Parotid gland tumor | 97 | Siemens | EPI, FS NI | Mono-exponential |
| 43 | Habermann et al., 2009 (70) | Normal parotid parenchyma | 100 | GE | EPI, both FS and no-FS, NI | Mono-exponential |
Philips, Philips Medical Systems, Best, Netherlands; Siemens, Siemens Medical Systems, Erlangen, Germany; GE, General Electric medical Systems, Milwaukee, WI, USA; EPI, echo planar imaging; HASTE, half-fourier acquisition single-shot turbo spin-echo; IVIM, intravoxel incoherent motion; DKI, diffusion kurtosis imaging; SPAIR, spectral pre-saturation attenuated inversion recovery; STIR, short-tau inversion recovery; SS, single-shot; TSE, turbo spin-echo; TSS, transversal single-shot; FS, fat-suppression; NI, type not indicated.