Department of Radiology, Yonsei University College of Medicine, Seoul, Republic of Korea.
Department of Radiology, Yonsei University College of Medicine, Seoul, Republic of Korea; Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Eur J Radiol. 2021 Jan;134:109409. doi: 10.1016/j.ejrad.2020.109409. Epub 2020 Nov 11.
Cryoneedles removal before sufficient thawing may lead to tissue damage and bleeding. We analyzed melting time of radiographic ice-ball in renal percutaneous cryoablation (PCA) using ultrasound.
Consecutive 27 patients who underwent PCA using cryoneedles of 2-4 for the renal mass (median size, 1.9 cm; range, 1.1-4.1 cm) were evaluated. Reconstructed CT images obtained during freezing were used to measure radiographic ice-ball volume. After completing final freezing, 5-min active thawing and following passive thawing were performed. Melting time of radiographic ice-ball during the thawing was analyzed by serial ultrasound examination. Melting time was defined as the time of complete disappearance of intrarenal posterior acoustic shadowing generated by radiographic ice-ball, which was analyzed by two independent radiologists. The relationship between total melting time and radiographic ice-ball volume was also analyzed by Spearman's rank correlation.
Median radiographic ice-ball volume was 30.5 cm (range, 26.6-37.3 cm). After 5-min active thawing, radiographic ice-ball needed additional passive thawing of median 8-min or 9-min for complete melting in analyses of two independent radiologists, respectively (p > 0.05). The range of total melting time during active and passive thawing was 9-min-to-15-min for both radiologists, respectively. A positive correlation was found between total melting time and radiographic ice-ball volume (Spearman's rho, 0.644 and 0.479 for radiologist 1 and 2).
In our PCA protocol, radiographic ice-ball needed approximately 10-min passive thawing after 5-min active thawing for complete melting. This may help determine safe removal time of cryoneedles.
在未充分解冻的情况下移除冷冻探针可能导致组织损伤和出血。我们分析了超声引导下肾经皮冷冻消融（PCA）中影像学冰球的融化时间。
连续 27 例因肾脏肿块（中位大小，1.9cm；范围，1.1-4.1cm）而行 PCA 的患者纳入本研究。使用冷冻过程中的重建 CT 图像来测量影像学冰球的体积。完成最终冷冻后，进行 5 分钟主动解冻和随后的被动解冻。通过连续超声检查分析解冻过程中影像学冰球的融化时间。将完全消失由影像学冰球产生的肾内后向声影的时间定义为融化时间，由两名独立的放射科医生进行分析。还通过 Spearman 秩相关分析来研究总融化时间与影像学冰球体积之间的关系。
中位影像学冰球体积为 30.5cm³（范围，26.6-37.3cm³）。在 5 分钟主动解冻后，两名独立放射科医生分析的结果分别为影像学冰球还需要额外的中位 9 分钟或 8 分钟的被动解冻才能完全融化（p＞0.05）。两位放射科医生的主动和被动解冻的总融化时间范围分别为 9 分钟至 15 分钟。总融化时间与影像学冰球体积之间存在正相关（放射科医生 1 和 2 的 Spearman's rho 值分别为 0.644 和 0.479）。
在我们的 PCA 方案中，在 5 分钟主动解冻后，影像学冰球需要大约 10 分钟的被动解冻才能完全融化。这可能有助于确定安全移除冷冻探针的时间。
