Table 1.

Periprostatic fat measurement techniques on imaging and their outcomes in previous studies.

Study	Reference standard	Treatment	Method	Imaging modality	Outcome
Woo et al.15 Korea N = 190	Radical prostatectomy	Surgery	Periprostatic and subcutaneous fat thicknesses.	Preoperative mid-sagittal T2W MRI. Measured the shortest perpendicular distance from symphysis pubis to skin and prostate.	Positive correlation between the periprostatic fat thickness and GS*
Roermund et al.7 Netherlands N = 902	Prostate biopsies (? number)	Brachytherapy	Periprostatic fat area (cm2)/subcutaneous fat thickness (cm).	Two transverse 3 mm-thick CT slices at different levels. Pelvic fat was defined by the density range −190 to −30 HU*. Fat density (%) was calculated by dividing periprostatic fat area by total contour area.	Periprostatic fat area and density were not correlated with Prostate cancer aggressiveness
Roermund et al. (2010) Netherlands N = 932	Prostate biopsies (? number)	External radiotherapy and brachytherapy	Periprostatic fat area (cm2)/Subcutaneous fat thickness.	Single transverse CT slice at the level of the femoral head and greater trochanter. Defined the pelvic fat by the density range −190 to −30 HU*. Fat density (%) was calculated by dividing periprostatic fat area by total contour area.	Higher periprostatic fat density had more often aggressive prostate cancer.
Bhindi et al.25 Canada N = 931	10–12 prostate biopsies	unknown	Periprostatic fat thickness.	Trans rectal ultrasonography (TRUS). The periprostatic fat was measured from the shortest perpendicular distance between pubic bone and prostate.	Periprostatic fat can be used as predictor for prostate cancer and high-grade prostate cancer at biopsy.
Tan et al.17 USA N = 295	12 core prostate biopsies	unknown	Periprostatic fat volume and prostate volume	3T MRIs. Periprostatic fat was marked from the level of its base to apex on T2W MR images ‘’cranial to caudal”. Ratio was calculated (fat volume/prostate volume)	Higher ratio may be a risk factor, is significantly associated with higher Gleason score
Zhang et al.16 China N = 184	Radical prostatectomy	Surgery	Periprostatic fat area (cm2) and Subcutaneous fat thickness	T2W transverse MRI slice at the level of the femoral head and greater trochanter of the femur.	Periprostatic fat can predict the prognosis of patient with radical retropubic prostatectomy.

*GS = Gleason score. *HU = Hounsfield unit.