Yoshiyuki Yamaguchi1, Takao Kamai1, Minoru Kobayashi2. 1. Department of Urology, Dokkyo Medical University, Tochigi, Japan. 2. Department of Urology, Utsunomiya Memorial Hospital, Tochigi, Japan.
Abstract
AIM: We examined the comparative accuracy of the portable ultrasound bladder scanner, Lilium α-200, and conventional ultrasonography (CUS) in bladder volume measurement. We also examined factors that could lead to measurement errors. METHODS: Postvoid residual (PVR) volume was measured by Lilium α-200 and CUS with catheterized volume as a comparator in 224 consecutive men, of which 109 were also measured for the serially inflated bladder with saline. The measurement accuracy with respect to the actual volume was evaluated by calculating the error volume (EV), % error volume (%EV), and their absolute values. Absolute %EV of ≤20% was designated as nonerror. The measurement of prostate volume, abdominal thickness, and pelvimetry was performed on magnetic resonance images. RESULTS: PVR volumes measured by CUS are better correlated with actual volumes (r = .779) than those of Lilium α-200 (r = .606). When the measurement accuracy was indicated by absolute values of EV and %EV, CUS provided a more accurate estimate (21 ± 21 ml, 60 ± 42%) than Lilium α-200 (32 ± 45 ml, 91 ± 142%). The frequency of error was significantly increased at lower bladder volumes. Overestimation was associated with larger prostate size for the Lilium α-200, while underestimation was associated with greater bladder flattening for both methods. CONCLUSION: PVR volumes measured by Lilium α-200 were fairly correlated with actual volumes. However, their relative errors were too large to correctly predict the actual volume. Flattened bladder and a large prostate may hinder accurate measurements. Consequently, Lilium α-200 is not superior to CUS and its feasibility is limited to when the precise measurement is not required.
AIM: We examined the comparative accuracy of the portable ultrasound bladder scanner, Lilium α-200, and conventional ultrasonography (CUS) in bladder volume measurement. We also examined factors that could lead to measurement errors. METHODS: Postvoid residual (PVR) volume was measured by Lilium α-200 and CUS with catheterized volume as a comparator in 224 consecutive men, of which 109 were also measured for the serially inflated bladder with saline. The measurement accuracy with respect to the actual volume was evaluated by calculating the error volume (EV), % error volume (%EV), and their absolute values. Absolute %EV of ≤20% was designated as nonerror. The measurement of prostate volume, abdominal thickness, and pelvimetry was performed on magnetic resonance images. RESULTS: PVR volumes measured by CUS are better correlated with actual volumes (r = .779) than those of Lilium α-200 (r = .606). When the measurement accuracy was indicated by absolute values of EV and %EV, CUS provided a more accurate estimate (21 ± 21 ml, 60 ± 42%) than Lilium α-200 (32 ± 45 ml, 91 ± 142%). The frequency of error was significantly increased at lower bladder volumes. Overestimation was associated with larger prostate size for the Lilium α-200, while underestimation was associated with greater bladder flattening for both methods. CONCLUSION: PVR volumes measured by Lilium α-200 were fairly correlated with actual volumes. However, their relative errors were too large to correctly predict the actual volume. Flattened bladder and a large prostate may hinder accurate measurements. Consequently, Lilium α-200 is not superior to CUS and its feasibility is limited to when the precise measurement is not required.