By using intraoperative ultrasound even after scanning with other imaging modalities, physicians can alter the course of surgery for liver tumors, and, in some cases, avoid surgery altogether, Austrian researchers have concluded.
Researchers from the University of Vienna assessed the impact of intraoperative ultrasound (IOUS) for liver tumors when preceded by magnetic resonance tomography (MRT), helical CT (HCT), or CT with arterial perfusion (CTAP). Dr. Rupert Prokesch from the university's department of radiology presented the results of this study at the European Congress of Radiology this month.
The group looked at 104 patients who underwent IOUS. Of these, 62 had preoperative HCT scans, 26 underwent MRI, 24 conventional CT, and eight patients had CTAP done prior to surgery. Of these, 37 had primary liver malignancies and 41 patients had metastatic lesions. Benign lesions were found in a dozen patients and 14 had other disease.
Overall, IOUS was able to detect lesions that hadn't been seen preoperatively in 26% of the cases; 12.5% of these lesions were malignant. The additional topographic information that was gathered by IOUS led the surgeon to change the operative strategy in about 37% of the cases, Prokesch said. In 26% of the cases, the decision against resection was made because of IOUS results. When used with CT or helical CT, the rate of lesions initially detected by IOUS was between 34%-40%. With MRT, CTAP, and MRT combined with helical CT, IOUS was first to detect nearly 17% of lesions.
Intraoperative ultrasound remains a highly useful tool for surgical planning, the study concluded. IOUS is almost a requirement for the preoperative staging of ethanol instillation and cryosurgery because of its ability to detect small, unknown lesions, Prokesch added.
Other studies back up the Austrian team's conclusions. Radiologists at Gazi University in Ankara, Turkey recommended that IOUS be done as a routine procedure with major liver surgery (Acta Radiol, January 2000, Vol.41(1), pp.97-101).
In this study, IOUS of the liver was performed in 116 patients, who also were evaluated preoperatively by ultrasonography, CT, and scintigraphy. Based on IOUS findings, the surgical procedure was altered in 43% of the cases or scaled back in 7% of the patients. IOUS revealed that 20% of the patients were inoperable.
"IOUS is a precise diagnostic method for staging the operability of liver tumors. Unnecessary surgical procedures can be avoided," the authors surmised.
Another paper, produced by German radiologists from the University of Witten-Herdecke in Wuppertal, compared the accuracy of IOUS to helical CT and portal-phase contrast enhancement (CTAP) in the preoperative detection of liver metastases. In this prospective study, 33 patients with colorectal carcinoma were evaluated with CTAP and IOUS. Both were able to detect all lesions measuring 5-10 mm. CTAP presented an ideal sensitivity of 100% but a low specificity of 68%. Sensitivity for IOUS was 98% and the specificity was 95%, although this modality did miss one metastasis that measured greater than 10 mm (World J Surg, January 2000, Vol.24 (1), pp. 43-47).
But a third study, out of Baylor University Medical Center in Dallas, found that iron oxide magnetic resonance imaging (Fe-MRI) outperformed contrast-enhanced CT and IOUS in the identification of hepatic tumors (Ann Surg Oncol, October 1999, Vol. 6(7), pp.691-698).
By Shalmali Pal
AuntMinnie.com staff writer
March 22, 2000
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