Hideho Endo

Feasibility of insertion/implantation of 2.0-mm-diameter gold internal fiducial markers for precise setup and real-time tumor tracking in radiotherapy.

PURPOSE To examine the feasibility and reliability of insertion of internal fiducial markers into various organs for precise setup and real-time tumor tracking in radiotherapy (RT). MATERIALS AND METHODS Equipment and techniques for the insertion of 2.0-mm-diameter gold markers into or near the tumor were developed for spinal/paraspinal lesions, prostate tumors, and liver and lung tumors. Three markers were used to adjust the center of the mass of the target volume to the planned position in spinal/paraspinal lesions and prostate tumors (the three-marker method). The feasibility of the marker insertion and the stability of the position of markers were tested using stopping rules in the clinical protocol (i.e., the procedure was abandoned if 2 of 3 or 3 of 6 patients experienced marker dropping or migration). After the evaluation of the feasibility, the stability of the marker positions was monitored in those patients who entered the dose-escalation study. RESULTS Each of the following was shown to be feasible: bronchoscopic insertion for the peripheral lung; image-guided transcutaneous insertion for the liver; cystoscopic and image-guided percutaneous insertion for the prostate; and surgical implantation for spinal/paraspinal lesions. Transcutaneous insertion of markers for spinal/paraspinal lesions and bronchoscopic insertion for central lung lesions were abandoned. Overall, marker implantation was successful and was used for real-time tumor tracking in RT in 90 (90%) of 100 lesions. No serious complications related to the marker insertion were noted for any of the 100 lesions. Using three markers surgically implanted into the vertebral bone, the mean +/- standard deviation in distance among the three markers was within 0.2 +/- 0.6 mm (range -1.4 to 0.8) through the treatment period of 30 days. The distance between the three markers gradually decreased during RT in five of six prostate cancers, consistent with a mean rate of volume regression of 9.3% (range 0.015-13%) in 10 days. CONCLUSIONS Internal 2.0-mm-diameter gold markers can be safely inserted into various organs for real-time tumor tracking in RT using the prescribed equipment and techniques. The three-marker method has been shown to be a useful technique for precise setup for spinal/paraspinal lesions and prostate tumors.

Registration accuracy and possible migration of internal fiducial gold marker implanted in prostate and liver treated with real-time tumor-tracking radiation therapy (RTRT)

BACKGROUND AND PURPOSE We have developed a linear accelerator synchronized with a fluoroscopic real-time tumor-tracking system to reduce errors due to setup and organ motion. In the real-time tumor-tracking radiation therapy (RTRT) system, the accuracy of tumor tracking depends on the registration of the markers coordinates. The registration accuracy and possible migration of the internal fiducial gold marker implanted into prostate and liver was investigated. MATERIALS AND METHODS Internal fiducial gold markers were implanted in 14 patients with prostate cancer and four patients with liver tumors. Computed tomography (CT) was carried out as a part of treatment planning in the 18 patients. A total of 72 follow-up CT scans were taken. We calculated the relative relationship between the coordinates of the center of mass (CM) of the organs and those of the marker. The discrepancy in the CM coordinates during a follow-up CT compared to those recorded during the planning CT was used to study possible marker migration. RESULTS The standard deviation (SD) of interobserver variations in the CM coordinates was within 2.0 and 0.4 mm for the organ and the marker, respectively, in seven observers. Assuming that organs do not shrink, grow, or rotate, the maximum SD of migration error in each direction was estimated to be less than 2.5 and 2.0 mm for liver and prostate, respectively. There was no correlation between the marker position and the time after implantation. CONCLUSION The degree of possible migration of the internal fiducial marker was within the limits of accuracy of the CT measurement. Most of the marker movement can be attributed to the measurement uncertainty, which also influences registration in actual treatment planning. Thus, even with the gold marker and RTRT system, a planning target volume margin should be used to account for registration uncertainty.

Tumor location, cirrhosis, and surgical history contribute to tumor movement in the liver, as measured during stereotactic irradiation using a real-time tumor-tracking radiotherapy system.

PURPOSE To investigate the three-dimensional (3D) intrafractional motion of liver tumors during real-time tumor-tracking radiotherapy (RTRT). MATERIALS AND METHODS The data of 20 patients with liver tumors were analyzed. Before treatment, a 2-mm gold marker was implanted near the tumor. The RTRT system used fluoroscopy image processor units to determine the 3D position of the implanted marker. A linear accelerator was triggered to irradiate the tumor only when the marker was located within a permitted region. The automatically recorded tumor-motion data were analyzed to determine the amplitude of the tumor motion, curve shape of the tumor motion, treatment efficiency, frequency of movement, and hysteresis. Each of the following clinical factors was evaluated to determine its contribution to the amplitude of movement: tumor position, existence of cirrhosis, surgical history, tumor volume, and distance between the isocenter and the marker. RESULTS The average amplitude of tumor motion in the 20 patients was 4 +/- 4 mm (range 1-12), 9 +/- 5 mm (range 2-19), and 5 +/- 3 mm (range 2-12) in the left-right, craniocaudal, and anterior-posterior (AP) direction, respectively. The tumor motion of the right lobe was significantly larger than that of the left lobe in the left-right and AP directions (p = 0.01). The tumor motion of the patients with liver cirrhosis was significantly larger than that of the patients without liver cirrhosis in the left-right and AP directions (p < 0.004). The tumor motion of the patients who had received partial hepatectomy was significantly smaller than that of the patients who had no history of any operation on the liver in the left-right and AP directions (p < 0.03). Thus, three of the five clinical factors examined (i.e., tumor position in the liver, cirrhosis, and history of surgery on the liver) significantly affected the tumor motion of the liver in the transaxial direction during stereotactic irradiation. Frequency analysis revealed that for 9 (45%) of the 20 tumors, the cardiac beat caused measurable motion. The 3D trajectory of the tumor showed hysteresis for 4 (20%) of the 20 tumors. The average treatment efficiency of RTRT was 40%. CONCLUSIONS Tumor location, cirrhosis, and history of surgery on the liver all had an impact on the intrafractional tumor motion of the liver in the transaxial direction. This finding should be helpful in determining the smallest possible margin in individual cases of radiotherapy for liver malignancy.

Complications of Percutaneous Transhepatic Portal Vein Embolization

PURPOSE Percutaneous transhepatic portal vein (PV) embolization (PTPE) is a useful preoperative procedure for extended liver resection. The purpose of the present study was to assess the frequency of technical complications of PTPE and to discuss the risks of this procedure. MATERIALS AND METHODS PTPE was performed in 46 patients. Forty-seven procedures were performed because an initial puncture failure required that the procedure be performed twice in one patient. The technical success rate and technical complications were assessed. Complications were analyzed with regard to approach methods and puncture sites. Approach methods were categorized as contralateral or ipsilateral. Puncture sites were categorized into anterior, posterior, and lateral segments. The results were compared statistically with use of the Fisher exact test. RESULTS Technical success was achieved in 45 of 47 procedures (95.7%). Complications occurred in seven of 47 procedures (14.9%), including pneumothorax in two, subcapsular hematoma in two, arterial puncture in one, pseudoaneurysm in one, hemobilia in one, and PV thrombosis in one. Subcapsular hematoma and pseudoaneurysm occurred in the same procedure. No patient died as a result of complications. There was no significant difference between the contralateral and ipsilateral approaches. The incidence of complications was significantly higher in procedures involving puncture of the posterior segment than in those involving puncture of the anterior segment (P =.0374). CONCLUSION In cases in which the anterior segment cannot be visualized for puncture, PTPE via the lateral segment or transileocolic portal embolization should be considered rather than PTPE via the posterior segment.

Outcome of MR-guided percutaneous cryoablation for hepatocellular carcinoma

PURPOSE To assess the mid-term results of MR-guided percutaneous cryoablation for small hepatocellular carcinoma (HCC). METHODS Using an argon-based cryoablation system, MR-guided percutaneous cryoablation was performed. The number of tumors was three or fewer. The maximum diameter of tumors was less than 5 cm when solitary and no more than 3 cm when multiple. The Kaplan-Meier method was used to calculate the survival of patients. RESULTS Among 15 patients, 16 tumors were treated. The maximum tumor diameter ranged from 1.2 to 4.5 cm, with a mean of 2.5 +/- 0.8 cm (mean +/- standard deviation). The volume of iceballs measured on MR-images was greater than that of the tumors in all cases. The follow-up period ranged from 10 to 52 months, with a mean of 36.6 +/- 12.1 months. One-year and 3-year overall survival were 93.8 and 79.3%, respectively. The complete ablation rate was 80.8% at 3 years. Immediate complications were pneumothorax, hemothorax, and pleural effusion. An ablation zone was not absorbed and content exuded from a scar of the probe tract 4 months after cryoablation in one patient. CONCLUSION MR-guided percutaneous cryoablation appears to be a feasible modality and potentially good option for the treatment of small HCC.

Embolization of the replaced common hepatic artery before surgery for pancreatic head cancer: report of a case.

We report the case of a patient with pancreatic head cancer, whose replaced common hepatic artery (RCHA) arose from the superior mesenteric artery (SMA). We performed preoperative embolization of the RCHA, after which the liver blood flow was well maintained by the left gastric artery. The patient underwent a radical operation involving en bloc resection of the RCHA without any serious complications.

Magnetic resonance-guided percutaneous cryoablation of uterine fibroids: early clinical experiences.

PurposeUterine fibroids (leiomyomas) are the most common tumors of the uterus. The present study evaluated the feasibility and effectiveness of magnetic resonance (MR)-guided percutaneous cryoablation for uterine fibroids as a minimally invasive treatment alternative.MethodsFrom August 2001 to June 2002, MR-guided percutaneous cryoablation was performed on seven uterine fibroids in 6 patients who displayed clinical symptoms related to tumors. Using a horizontal-type open MR system, cryoablation probes were percutaneously placed in fibroids. Fibroids were ablated, and the site and size of ice balls were monitored on MR imaging. Postoperatively, patients completed a questionnaire to assess changes in presenting clinical symptoms, and MR images were obtained for all patients at follow-up. Changes in clinical symptoms and tumor volume were evaluated in each patient.ResultsAll treated patients showed reductions in tumor size. Mean volume reduction rate was 40.3% at 6 weeks postoperatively, and 79.4% at 9–12 months. All patients reported fever after treatment. Surgical drainage was required for abscess in the probe channel in one patient, and transient liver damage occurred in another. Subjective symptoms improved in all patients except one who had multiple tumors, and no patient complained of new symptoms after cryoablation during follow-up.ConclusionMR-guided percutaneous cryoablation represents a feasible and effective treatment for uterine fibroids.

Spontaneous Rupture of Hepatocellular Carcinoma Supplied by the Right Renal Capsular Artery Treated by Transcatheter Arterial Embolization

We present a case of spontaneous rupture of hepatocellular carcinoma (HCC) with poor liver function which was treated by transcatheter arterial embolization (TAE). The patient’s bilirubin value was 3.8 mg/dL. The tumor was fed by the right renal capsular artery according to selective arteriography. It was subsequently treated by TAE. With successful TAE, no hepatic failure was related to the treatment. We believe that if tumors are fed only by extrahepatic collateral vessels, TAE may be an effective treatment even in patients with poor liver function.

Usefulness of 3-Dimensional Reconstructed Images of Renal Arteries Using Rotational Digital Subtraction Angiography

PURPOSE We assess the feasibility of a 3-dimensional (D) reconstruction technique of rotational digital subtraction angiography (DSA) for visualization of the renal arteries. MATERIALS AND METHODS We evaluated 28 kidneys in 20 patients. Rotational DSA images were obtained during a deep inspiratory pause after contrast material injection through the renal artery. Acquired data were transferred to an image workstation and reconstructed as 3-D images. Visibility of the main trunk of the renal artery, segmental arteries, interlobar arteries and arcuate arteries was classified as grade 4-excellent, grade 3-good, grade 2-satisfactory and grade 1-poor. The 3-D reconstructed images were compared with conventional 2-D DSA performed just before the rotational DSA. The criteria for evaluation were visibility of the aneurysm neck in 8 cases of aneurysm, delineation of the feeding arteries in 6 cases of renal lesions and visibility of the relationship between renal branches in other cases. RESULTS Delineation of grades 4 to 1 was 93%, 7%, 0% and 0% for the main renal artery, 66%, 21%, 7% and 6% for segmental arteries, 61%, 11%, 21% and 7% for interlobar arteries, and 36%, 18%, 36% and 10% for arcuate arteries, respectively. The 3-D images had the advantage over 2-D DSA in 75% of cases. In all cases of aneurysm 3-D images were obviously more useful than 2-D DSA. CONCLUSIONS 3-D images of renal arteries obtained with rotational DSA are considered acceptable for clinical use.