Clinical Application

When treating healthy kidneys of eight patients with extracorporeally applied HIFU in a phase 1 study, Vallancien et al. [19] did not observe any significant changes in the usual laboratory parameters, except for a transient increase in creatine phosphokinase after a long pulse. Side effects included skin burns. Kohrmann et al. [41] applied HIFU to healthy kidney tissue of 24 patients immediately before nephrectomy. In 19 out of the 24 cases, hemorrhage or necrosis was detected macroscopically. Histologically, interstitial hemorrhages and fiber rupture, as well as collagen fiber shrinkage with eosinophilia, were detected in the focal area.

In a phase 2 study, Vallancien et al. [19] treated four patients with T2-T3 renal tumors with HIFU 2,6,8, and 15 days before they underwent nephrectomy. Histological examination of the treated kidneys revealed a coagulation necrosis in the targeted tumor area. In two cases, a small edema formed in the perirenal fat tissue during surgery. No subcapsular or perirenal hematomas were noted. The muscle wall (lumbar incision) was normal in all cases, and there were no lesions of the adjacent organs (colon, inferior vena cava, duodenum, ureter, and renal pelvis). During operations performed on days 2 or 3, a clearly demarcated necrotic area was detected, corresponding to the selected volume. No adverse systemic effects were observed. Two patients had localized first-degree and third-degree skin burns.

Ktirmann and colleagues [21] recently reported on a patient with three renal tumors who underwent HIFU in three sessions under general or sedation anesthesia and who was followed by clinical examinations and MRI for 6 months. After HIFU treatment, MRI indicated necrosis in the two tumors of the lower pole of the kidney within 17 and 48 days. The necrotic area in these two tumors shrunk thereafter within 6 months (tumor 1 shrank from 2.3 cm, as shown in Fig. 1, to 0.8cm, as shown in Fig. 2; tumor 2 shrank from 1.4cm, as shown in Fig. 1, to 1.1cm, as shown in Fig. 3). Unfortunately, one tumor in the upper pole (2.8 cm) was inadequately treated because of absorption of ultrasound energy by the interposed ribs. During one session, a skin burn of grade 2 occurred.

Wu et al. [22] reported on their preliminary experience using HIFU for the treatment of patients with advanced-stage renal malignancy. HIFU treatment (median hours of therapy, 5.4; range, 1.5 to 9) was performed in 12 patients with advanced-stage renal-cell carcinoma and 1 patient with colon cancer metasta-sized to the kidney (median tumor size, 8.7 cm; range, 2 to 15).All patients under-

Fig. 1. Before HIFU application: two tumors in the lower pole of the kidney

Fig. 1. Before HIFU application: two tumors in the lower pole of the kidney

Fig. 2. Six months after HIFU treatment: shrinking of tumor 1

went HIFU treatment safely, including 10 who had partial tumor ablation and 3 who had complete ablation. After HIFU, hematuria disappeared in 7 of 8 patients and flank pain of presumed malignant origin disappeared in 9 of 10 patients. The postoperative images showed decrease in or absence of tumor blood supply in the treated region and significant shrinkage of the ablated tumor. Of the 13 patients, 7 died (median survival, 14.1 months; range, 2 to 27) and 6 were still alive after a median follow-up of 18.5 months (range, 10 to 27). A minor skin burn was observed in the first patient, which had healed 2 weeks after HIFU.

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