Ultrasound imaging (USI) has been demonstrated to produce valid and reliable measures to characterize the anatomical structure of the bladder wall and urethra, as well as motion of the anorectal angle during pelvic floor muscle (PFM) contraction. [1] USI has consequently been used to investigate urogenital morphology in both healthy and incontinent women, but not in women who have been irradiated for pelvic cancer. As many women report pelvic floor dysfunction after pelvic radiotherapy (RT) [2], evidence is needed to support the use of USI for the investigation of pelvic floor dysfunction in women with pelvic cancer treated with RT. This is important as tissue fibrosis after RT may impair image quality. Therefore, the aim of this study is to evaluate the feasibility of using USI to measure bladder wall thickness (BWT), urethral length (UL) and PFM function in women who have received pelvic RT.

This feasibility study was conducted in a university hospital as a prerequisite to a larger intra- and inter-rater reliability study in which women who have received RT for the treatment of a cancer located in the pelvic area, will participate. Six women with a history of RT for pelvic cancer underwent a 2D transperineal USI examination (Aplio 500, Toshiba, California, USA) of their pelvis. Using a 3-7MHz curved-array transducer, in dorsal lithotomy position and after complete bladder voiding, USI assessments were carried out independently by two trained raters: one resident in radiology (R1) and one physiotherapist (R2). R1 performed 2 assessments, each separated by a 30-minute interval, while R2 performed a single assessment on the same day. Five variables were collected 1) BWT, determined by the mean perpendicular distance (3 measures per image) between the inner and outer rim of the superior bladder wall; 2) UL, as the curved-path distance between the bladder neck and the point corresponding to the most inferior and posterior aspect of the pubic symphysis; 3) levator plate length at rest (LPR) as the distance between the ano-rectal angle and pubic symphysis; 4) levator plate length during a maximal voluntary contraction of the PFM (MVC); and 4) levator plate length during a maximal Valsalva manoeuvre (MVM). Feasibility and acceptability were determined by compliance with the assessment procedures, ability to identify anatomical landmarks, and tolerance with the assessment procedures and protocol duration. For each USI variable, three images were collected per assessment, the mean of these was retained for analysis. The range of values obtained, the mean of differences between raters, and the concordance between raters was determined graphically for each outcome.

Six women were assessed over a 2-month period. Participants were aged between 33 and 73 years old, were between 5 and 48 months post-RT, and had received between 21 and 57 total RT Gray (Gy) dose (see Table I). Descriptive analyses demonstrate compliance with the protocol for all measures. Anatomical landmarks were identified in all participants, regardless of their medical condition. Mean duration of a single assessment was 22 ± 9 min, which was longer for Rater 2 (R1: 18 ± 7 min; R2: 32 ± 3 min). No pain or discomfort was reported by participants (0/10 for every assessment and participant). Preliminary data from R1 and R2 assessments show the following means of difference and values ranged as follows: BWT: -0.4 mm [2.0 – 5.4], UL: 2.6 mm [24.7 – 38.0], LPR: -2.1 mm [46.9 – 58.4], MVC: 0.2 mm [37.7 – 51.8], and MVM: 0.6 mm [45.7 – 66.5]. Comparison of measurements between the two R1 assessments generated: BWT: 0.7 mm [1.6 – 3.4], UL: -0.2 mm [29.7 – 38.8], LPR: -2.5 mm [46.9 – 56.7], MVC: -0.2mm [39.1 – 53.3], and MVM: -2.9 mm [47.1 – 67.0]. A graphical representation of measures obtained during MVC allowed for the appreciation of concordance between raters and between repeated measures by R1 for this variable (Figure I).

Feasibility and acceptability of USI procedures for the measurement of BWT, UL and PFM variables are supported by compliance with the protocol, an adequate duration for the complete assessment and no discomfort reported by the participants. Mean differences between raters or between assessments by R1 are small in comparison with the range of values among participants, except for BWT. The ranges of values appear to correspond with existing values from the literature, [1, 3] and the intra-rater concordance of all measurements appears to be higher than inter-rater concordance. The shorter assessment duration for R1 may be explained by greater previous experience with USI.

This is the first time that USI has been used to investigate urogenital morphology in women who have received pelvic RT. Specifically we measured BWT, UL and PFM function. This study supports the feasibility and acceptability of USI for these variables in a heterogenous sample of women who previously received RT and thus in whom the soft tissues may have been affected. Raters with different experience in USI appear to show good concordance. Based on these results, we will move ahead to determine intra- and inter-rater reliability of these measures. USI is likely to be a valuable option for the investigation of pelvic floor dysfunctions in women who have been irradiated for pelvic cancer.

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Pomian A, Majkusiak W, Kociszewski J, et al. Demographic features of female urethra length. Neurourology and urodynamics. 2018.