Junji Machi

Ultrasound-guided radiofrequency thermal ablation of liver tumors: percutaneous, laparoscopic, and open surgical approaches

Only 10% to 20% of patients with primary and colorectal metastatic liver tumors are candidates for curative surgical resection. Even after curative treatment, tumors recur commonly in the liver. As a less invasive therapy, radiofrequency thermal ablation (RFA) of primary, metastatic, and recurrent liver tumors was performed under percutaneous, laparoscopic, or open intraoperative ultrasound guidance. The safety and local control efficacy of RFA were investigated. RFA was performed mostly in patients with unresectable hepatomas or metastatic liver tumors. Patients with large tumors, major vessel or bile duct invasion, limited extrahepatic metastases, or liver dysfunction were not excluded. An RFA system with a 15-gauge electrode-cannula with four-pronged retractable needles was used. All patients were followed for more than 8 months to assess morbidity and mortality, and to determine tumor recurrence. Sixty RFA operations were performed in 46 patients: 11 patients underwent repeat RFA once or twice. A total of 204 tumors were treated: 70 hepatomas and 134 metastatic tumors. Tumor size ranged from 5 mm to 180 mm (mean 36 mm). RFA was performed in 29 operations for 81 tumors percutaneously, in seven operations for 14 tumors laparoscopically, and in 24 operations for 109 tumors by open surgery. Combined colorectal resection was carried out in five operations and combined hepatic resection was carried out in three operations. There was one death (1.7%) from liver failure, and there were three major complications (5%): one case of bile leakage and two biliary strictures due to thermal injury. There were no intra-abdominal infectious or bleeding complications. The length of hospital stay ranged from 0 to 2, 1 to 3, and 4 to 7 days for percutaneous, laparoscopic, and open surgical RFA, respectively. During a mean follow-up period of 20.5 months, local tumor recurrence at the RFA site was diagnosed in 18 (8.8%) of 204 tumors. The risk factors for local recurrence included large tumor size and major vessel invasion: recurrence rates for tumors less than 4 cm, 4 to 10 cm, and greater than 10 cm, and for those with vessel invasion were 3.3%, 14.7%) 50%) and 47.8%) respectively. Ten of 18 tumors recurring locally were retreated by RFA, and eight of them showed no further recurrence. Ultrasound-guided RFA is a relatively safe, well-tolerated, and versatile treatment option that offers excellent local control of primary and metastatic liver tumors. The appropriate use of percutaneous, laparoscopic, and open surgical RFA is beneficial in the management of patients with liver tumors in a variety of situations.

Localization and Surgical Treatment of Pancreatic Insulinomas Guided by Intraoperative Ultrasound

BACKGROUND Approximately 20% to 60% of insulinomas cannot be localized preoperatively, and 10% to 20% cannot be found even during surgery. The operative complications associated with the blind surgical explorations are relatively high. METHODS Between January 1987 and December 1995, intraoperative ultrasound was used to localize insulinomas and guide surgical procedures in 28 patients. RESULTS Insulinomas were found by intraoperative systematic palpation in 24 patients (85.7%), while intraoperative ultrasound localized the tumors in 27 patients (96.4%). By the combination of these two techniques, all tumors were discovered. The surgical procedures were guided by intraoperative ultrasound. The operative complication rate was 14.3%. CONCLUSION Intraoperative ultrasound can accurately localize insulinoma, and delineate the spatial relationship between tumor and vital structures, such as pancreatic duct, common bile duct, and critical blood vessels. It can thereby help to increase the successful rate of surgery and avoid unnecessary blind pancreatectomy.

Laparoscopic ultrasonography versus operative cholangiography during laparoscopic cholecystectomy: review of the literature and a comparison with open intraoperative ultrasonography

BACKGROUND Laparoscopic ultrasonography (LUS) has been used increasingly over the last several years as a new imaging modality. To define the role of LUS during laparoscopic cholecystectomy, we evaluated LUS by prospectively comparing it with operative cholangiography (OC), by reviewing the literature on LUS, and by retrospectively comparing it with intraoperative ultrasonography performed during open cholecystectomy. STUDY DESIGN LUS and OC were compared prospectively in 100 consecutive patients during laparoscopic cholecystectomy. The success rate of examination, the time required, the accuracy in diagnosing bile duct calculi, and the delineation of biliary anatomy were evaluated. RESULTS The success rate of examination was 95% for LUS and 92% for OC. The main reason for unsatisfactory LUS was incomplete visualization of the distal common bile duct. The time required was 8.2 minutes for LUS and 15.9 minutes for OC (p<0.0001). Nine patients had bile duct calculi. LUS had one false-negative result and OC had two false-positives and one false-negative. The accuracies of LUS and OC were comparable except for a slightly better positive predictive value of LUS (100% versus 77.8%; p>0.1). In a literature review, 12 recent prospective studies comparing LUS and OC and three studies on open intraoperative ultrasonography were reviewed. Twelve studies of LUS with a total of 2,059 patients demonstrated results similar to the present study. The success rate was 88% to 100% for both tests. The time for LUS was approximately 7 minutes, about half of the time needed for OC. Overall, LUS was associated with fewer false-positive results than OC; the positive predictive value and specificity of LUS were better, while the sensitivity and negative predictive value of LUS and OC were comparable. OC detected ductal variations or anomalies more distinctly than LUS. Compared with open intraoperative ultrasonography, LUS had a slightly lower success rate and required a slightly longer time because it was technically more demanding, but the two procedures had a similar accuracy for diagnosing bile duct calculi. CONCLUSIONS Because of their different advantages and disadvantages, LUS and OC can be used in a complementary manner. There is a learning curve for LUS because of its technical difficulty. Once learned, however, LUS can be used as the primary screening procedure for bile duct calculi because of its safety, speed, and cost-effectiveness. OC can be used selectively, particularly when ductal anatomic variations or anomalies or bile duct injuries are suspected.

History of intraoperative ultrasound

Intraoperative ultrasound (IOUS) using A-mode or non-real-time B-mode imaging started in the 1960s; however, it was not widely accepted mainly because of difficulty in image interpretation. In the late 1970s, IOUS became one of the topics in the surgical communities upon the introduction of high-frequency real-time B-mode ultrasound. Special probes for operative use were developed. In the 1980s, all over the world the use of IOUS spread to a variety of surgical fields, such as hepatobiliary pancreatic surgery, neurosurgery, and cardiovascular surgery. IOUS changed hepatic surgery dramatically because IOUS was the only modality that was capable of delineating and examining the interior of the liver during surgery. After 1990, color Doppler imaging and laparoscopic ultrasound were incorporated into IOUS. Currently, IOUS is considered an indispensable operative procedure for intraoperative decision-making and guidance of surgical procedures. For better surgical practice, education of surgeons in the use of ultrasound is the most important issue.

The role of imaging ultrasound during pancreatic surgery.

Real-time ultrasound imaging was employed at 122 operations for the complications of pancreatitis, adenocarcinoma, and islet cell tumors. Ultrasound was found to be useful in 69% of the operations for pancreatitis and 66% of the operations for tumor. Assistance was provided in diagnosis or definition of pathology. Help in diagnosis consisted in detecting conditions that were not found on preoperative testing or at exploration and excluding conditions that were suspected on the basis of previous diagnostic studies or findings at operation. Better definition of pathology was provided by precise localization of structures, assessment of their size and surrounding anatomy, and distinction of tissue features that helped to recognize their identity. Ultrasound was usually more helpful in defining pathology than in diagnosis. Ultrasound enabled early orientation to important landmarks, reduced the need for contrast x-ray studies, and yielded unique information about the etiology of abnormalities. Although ultrasound has a slow learning curve, we believe that its use during pancreatic operations can significantly aid the surgeon and we recommend its wider application in surgical practice.

In vitro diagnosis of axillary lymph node metastases in breast cancer by spectrum analysis of radio frequency echo signals

Axillary lymph node status is of particular importance for staging and managing breast cancer. Currently, axillary lymph node dissection is performed routinely in cases of invasive breast cancer because of the lack of accurate noninvasive methods for diagnosing lymph node metastasis. We investigated the diagnostic ability of ultrasonic tissue characterization based on spectrum analysis of backscattered echo signals to detect axillary lymph node metastasis in breast cancer in vitro compared with in vitro B-mode imaging. Immediately after surgery, individual lymph nodes were isolated from axillary tissue. Each lymph node was scanned in a water bath using a 10-MHz instrument, and radio frequency data and B-mode images were acquired. Spectral parameter values were calculated, and discriminant analysis was performed to classify metastatic and nonmetastatic lymph nodes. Forty histologically characterized axillary lymph nodes were enrolled in this study, including 25 nonmetastatic and 15 metastatic lymph nodes. A significant difference existed in the spectral parameter values (slope and intercept) for metastatic and nonmetastatic lymph nodes. Spectral parameter-based discriminant function classification of metastatic vs. nonmetastatic lymph nodes provided a sensitivity of 93.3%, specificity of 92.0%, and overall accuracy of 92.5%. In comparison, B-mode ultrasound images of in vitro lymph nodes provided a sensitivity of 73.3%, specificity of 84.0%, and overall accuracy of 80.0%. Receiver operating characteristic (ROC) analysis comparing the efficacy of both methods gave an ROC curve area of 0.9888 for spectral methods, which was greater than the area of 0.8980 for B-mode ultrasound. Hence, this in vitro study suggests that the diagnostic ability of spectrum analysis may prove to be markedly superior to that of B-mode ultrasound in detecting axillary lymph node metastasis in breast cancer. Because of these encouraging results, we intend to conduct an investigation of the ability of spectral methods to classify metastatic axillary lymph nodes in vivo.

Technique of laparoscopic ultrasound examination of the liver and pancreas

Since the introduction of a recent laparoscopic ultrasound (LU), the value of this modality in examining the liver and pancreas has been reported. However, a precise scanning technique of LU has not previously been described. Based on our experience with intraoperative ultrasound during laparotomy, we have developed a technique for complete examination of the entire organs using a rigid LU probe. A 7.5-MHz rigid probe, 10 mm in diameter, was employed. The scanning was performed through three trocar ports: right subcostal, subxiphoid, and umbilical. For the liver, the subcostal scanning provided fundamental transverse views. The subxiphoid and umbilical scanning delineated the areas unable to be imaged by the subcostal scanning. For the pancreas, the subcostal and umbilical scanning demonstrated longitudinal and transverse views, respectively. The subxiphoid scanning enhanced examination of the pancreatic head. Three basic probe maneuvers (advancement-withdrawal, lateral movement, and rotation) and various scanning techniques (contact, probe-standoff, and compression scanning) should be utilized appropriately. With a rigid probe, complete LU examination of the liver and pancreas is possible using these techniques. We believe the present scanning method will help more surgeons learn LU.

In vitro investigation of lymph node metastasis of colorectal cancer using ultrasonic spectral parameters.

Lymph node involvement is one of the major factors affecting the prognosis of colorectal cancer. Various imaging methods, including ultrasound and computed tomography, are not sufficiently sensitive or specific for reliably determining lymph node involvement. We investigated the feasibility of using ultrasonic tissue characterization (UTC) based on spectrum analysis of backscattered echo signals for diagnosing lymph node metastasis of colorectal cancer in vitro. Forty lymph nodes, including 17 metastatic and 23 nonmetastatic nodes, from 11 colorectal cancer operations were investigated. Lymph nodes were scanned using a clinical instrument; B-mode imaging was performed for each lymph node, and radiofrequency (RF) data were acquired. The UTC parameters, slope and intercept, were calculated from the normalized power spectrum of the backscattered echo signals from each lymph node. The mean values of UTC parameters of metastatic and nonmetastatic lymph nodes were compared. The accuracy of UTC in distinguishing metastatic from nonmetastatic lymph nodes was calculated using discriminant analysis. Receiver operating characteristic (ROC) analysis was performed to compare the classification efficacy of UTC and B-mode ultrasound. UTC parameters demonstrated a significant difference in parameter values between metastatic and nonmetastatic lymph nodes. The overall accuracy in diagnosing the lymph node metastasis was 87.5% for UTC and 77.5% for B-mode ultrasound. ROC analysis produced an ROC curve area of 0.92 or 0.89 for UTC (depending on the performance-assessment algorithm) and 0.84 for B-mode ultrasound, which indicated that UTC performed markedly better than B-mode ultrasound in diagnosing metastatic lymph nodes. The advantages of UTC over conventional B-mode ultrasound in discriminating metastatic lymph nodes from nonmetastatic lymph nodes are extremely encouraging, and warrant an in vivo UTC study.

Focal Peliosis Hepatis Resembling Metastatic Liver Tumor

A 74 year old man had a history of subtotal gastrectomy for gastric cancer 9 years ago. Results of follow-up routine transabdominal ultrasonography 3 years ago and CT scan 5 years ago were normal except for the presence of multiple liver cysts. The patient had been asymptomatic. However, the most recent ultrasonogram using a 3.5 MHz probe (ATL Ultramark 9, Advanced Technology Laboratories, Bothell, WA) demonstrated a new 2 cm hyperechoic lesion at the dome of the right lobe of the liver (Fig. 1). Although this could represent a hemangioma or other benign tumor, malignancy needed to be ruled out. Biphasic CT scan was performed and confirmed the presence of the lesion (Fig. 2). The CT findings raised the possibility of a metastatic tumor more strongly. Because of the patient’s history of gastric cancer, upper gastrointestinal contrast study was performed; this showed a 2 × 5 cm irregular tumor in the upper thoracic esophagus, although the gastric remnant was normal. The esophageal tumor was a squamous cell esophageal cancer, diagnosed by subsequent endoscopy with biopsy. The treatment of esophageal cancer would be different depending on the pathologic nature of the liver lesion (i.e., metastatic or not). Percutaneous biopsy of the liver lesion was thought to be difficult owing to its size and location. MR imaging was thus performed and showed signal characteristics suggestive of a metastasis (Fig. 3). The patient had no other chronic diseases and was not taking any medication. Laboratory studies, including liver function tests, were unremarkable. The patient underwent laparotomy first to determine the histologic features of the Received March 25, 1998, from the Department of Surgery, University of Hawaii at Manoa, John A. Burns School of Medicine and Kuakini Medical Center, Honolulu, Hawaii. Revised manuscript accepted for publication June 7, 1998. Address correspondence to Junji Machi, MD, PhD, Department of Surgery, University of Hawaii at Manoa, John A. Burns School of Medicine, 320 Ward Avenue, Suite 200, Honolulu, HI 96814. ABBREVIATIONS

Radiofrequency ablation for multiple hepatic metastases.

With interest, I read an article by Dr. Sharon M. Weber and associates, titled “Survival After Resection of Multiple Hepatic Colorectal Metastases” published in the Annals of Surgical Oncology.1 They have shown excellent results of aggressive surgical resectional treatment of four or more metastatic tumors from colorectal cancer. Their findings are important because this number of multiple metastases has been considered to be a relative contraindication to hepatic resection. The morbidity and mortality of their experiences are excellent, as well as the long-term survival. Obviously, their results suggest that this kind of aggressive surgical approach is justified in selected patients. However, I think, many surgeons are not yet willing to perform surgical resection of bilobar metastatic tumors of more than four or five in number. Hepatic resection is still a major surgery, and a low morbidity and mortality achieved by experts like Dr. Weber and associates may not be possible by many general surgeons. As mentioned in their discussion, the use of radiofrequency thermal ablation (RFA) has been investigated over the last several years. This new modality has been used mainly for unresectable hepatic tumors. The main advantages of RFA treatment are its relative safety, less invasiveness, and the capability of percutaneous approach. Although bleeding and infectious complications are major risks for hepatic resection, these complications are rare with RFA. The local recurrence rate because of ablation treatment failure has been reported to be about 10%, even as low as 2%, 2–4 although the long-term results of this ablation are not available at this time. Another advantage of RFA is that it can be used for tumors that invade or are adjacent to major intrahepatic vascular structures that cannot be resected with an adequate or negative margin. In their discussion, they have described that most surgeons who perform local ablation are unwilling to treat more than three to five tumors or lesions greater than 4–5cm in size. I believe that this statement is not necessarily true. I know that some investigators of RFA have been treating more than five tumors and ones that are greater than 5 cm in size. In my experience with RFA of more than 100 operations for more than 300 hepatic tumors, the average size of the tumors was 36 mm, and about one third of the tumors were greater than 5cm in size.5 Also, in about one third of the operations, four or more tumors per operation have been ablated. Multimodality treatment is required, as they mentioned, to obtain the best chance for cure in patients with colorectal hepatic metastases. Surgical resection and ablation methods are the modality for local control. Even with these local control methods, many patients develop new recurrent tumors in the liver that are diagnosed at follow-up. Regional and/or systemic chemotherapy may decrease such hepatic recurrence. However, once these recurrences occur in the liver, another controversial issue is the indication for re-resection or repeat resection. In my experience and also that of other investigators, RFA can be repeated many times because of its relative safety. In particular, repeat percutaneous RFA is less invasive and is more acceptable to patients who have already had previous major operations. Also, RFA can be safely performed for synchronous multiple hepatic metastases in conjunction with colorectal resection for primary cancer. 6