Ultrasound-based liver computer assisted surgery.

Ongoing research toward development of a computer-assisted, ultrasound-based software/hardware tool to improve instrument positioning in moving organs during minimally invasive abdominal surgery is presented. The main objective of this research is to calculate, in real time and without user intervention, the pre-/intra-operative 3D/2D image misalignment due to patient respiration and the shift induced by the surgical instrument. Our methodology applied to the particular case of the liver, and partial results related to the image registration approach, based on organ segmentation and shape description, are presented. Preliminary results are highly encouraging. Among other benefits, use of this tool will increase surgeon confidence and improve surgery outcomes.

Image-guided prostate cryosurgery: state of the art.

BACKGROUND: Cryosurgery was first used to treat prostate cancer in the early 1970s but it was not until 1993, when the results from percutaneous ultrasound-guided cryosurgery were published, that the potential advantages of this treatment became apparent. Changes in equipment and techniques have improved the results of cryosurgery, in both tumor control and lower morbidity. METHODS: The author has reviewed data of his own and those of others concerning the changes in techniques employed and outcomes from prostate cryosurgery. RESULTS: Ultrasound-guided percutaneous transperineal placement of the cryoprobes allows monitoring of freezing in real time. Monitoring temperature at critical locations, separating the rectum and prostate by saline injection, and using argon gas rather than liquid nitrogen-based equipment have improved results and lowered complication rates. The technique produces outcomes similar to those obtained with brachytherapy and three-dimensional conformal radiation therapy. CONCLUSIONS: Advantages of cryosurgery include the ability to re-treat patients without added morbidity and to treat salvage postradiation patients with acceptable results and morbidity. The recent demonstration that "nerve-sparing" cryosurgery is possible suggests that cryosurgery may be used more often.

Percutaneous diskectomy in the treatment of herniated lumbar disks.

APLD and the minimally invasive approach to spine surgery has stood the test of time successfully. With the advent of new imaging technologies to aid in the guidance of spine procedures, such as three-dimensional ultrasound, interventional MR imaging, and fluoroscopic CT, and the development of flexible instruments that can be navigated within the disk, the stage is now set for major breakthroughs in the treatment of herniated lumbar disks (i.e., the minimally invasive removal of extruded and free disk fragments). With the active role of radiologists and sophisticated imaging, minimally invasive spinal intervention has a bright and exciting future.

Cryosurgery for prostate cancer: improved glandular ablation by use of 6 to 8 cryoprobes.

OBJECTIVES: To describe and assess the efficacy for increased glandular destruction by using 6 to 8 cryoprobes in place of the traditional 5 probes. METHODS: In April 1996, a revised method for cryosurgery was begun that uses 6 to 8 cryoprobes, and by July 1997, 81 men had been treated. This group was compared retrospectively to our last 82 cases done before April 1996 using 5 cryoprobes. All cases were consecutive. To ensure that the groups were similar, comparison was performed of entrance prostate-specific antigen (PSA), clinical stage, and Gleason score. Six months after cryosurgery, PSA and residual epithelial acini were compared between the two groups. RESULTS: The two groups were comparable for all the above parameters (P >0.05). The degree of overall glandular kill was greater for the 6 to 8-probe method (P = 0.023). Complete glandular ablation for the 5-probe and 6 to 8-probe methods was 39% and 53%, respectively, and the difference was not significant (P = 0.072). However, when one combined the complete glandular ablation group with the none to few residual acini group, 67.5% for the 5-probe method and 88.9% for the 6 to 8-probe method, a significant difference was found (P = 0.001). The odds of having many remaining acini versus having none to few were 3.5 times greater in the 5-probe group than in the 6 to 8-probe group. The mean and median PSA for the 5- and 6 to 8-probe groups were 0.19 and 0.1 versus 0.11 and 0.07 ng/mL, respectively, a significant difference (P = 0.02). No difference was found in rates of tumor persistence or complications. CONCLUSIONS: A revised method for cryosurgery using 6 to 8 cryoprobes has proved to be more effective for near-glandular ablation than the traditional 5-probe method. It was easily applied, had a wide margin of safety, and even shortened learning time. These innovations have permitted a closer approach to the goal of complete glandular destruction.

Nuances in percutaneous discectomy.

This article presents an update of the field of percutaneous discectomy and a perspective as to where percutaneous discectomy currently fits in the treatment of patients with herniated discs. The future of minimally invasive disc surgery is also entertained, and a novel approach to lumbar disc surgery is presented.

Minimally invasive disc surgery. Nucleotomy versus fragmentectomy.

There is continued debate as to the optimum surgical management of a herniated disc with sciatica. There are proponents of conventional microdiscectomy as well as those who advocate minimally invasive approaches, including central disc decompression or nucleotomy as well as arthroscopic lumbar microdiscectomy and fragmentectomy. In this controversy (I), Dr. Gary Onik takes the position that central disc decompression is both safe and efficacious and may be the procedure of choice for recurrent disc herniations (II). Dr. Parvis Kambin takes the opposing position and advocates arthroscopically assisted fragmentectomy as the procedure of choice.

Effect of thermal variables on frozen human primary prostatic adenocarcinoma cells.

OBJECTIVES: Recent advances in imaging technology and cryotechnology have rekindled interest in prostate cryosurgery. Cryosurgery, however, cannot be applied precisely without knowing how the thermal variables used during the procedure affect tissue destruction. The goal of this article is to provide quantitative values for the relationship between thermal variables during freezing and the destruction of human primary prostatic adenocarcinoma cells. METHODS: Human primary prostatic adenocarcinoma cells were frozen with controlled thermal parameters, using a directional solidification apparatus. Cell viability was determined after thawing, using trypan blue and a two-dye fluorescent test and correlated to the thermal variables used during freezing. RESULTS: Human primary prostatic adenocarcinoma cells are damaged by intracellular chemical damage when frozen with cooling rates lower than 5 degrees C/min and by intracellular ice formation when frozen with cooling rates higher than 25 degrees C/min. A double freeze/thaw cycle is required to ensure complete cell destruction at high subzero temperatures, which must be lower than -40 degrees C for the low cooling rates and lower than -19 degrees C for the higher cooling rate. CONCLUSIONS: Haphazard freezing does not necessarily destroy tissue during cryosurgery; however, quantitative data on the relation between thermal variables and frozen cell destruction can provide the means for performing cryosurgery more precisely and with greater control over the outcome of the procedure.

Automated percutaneous biopsy in the diagnosis and treatment of infectious discitis.

The author's experience using automated disc aspiration for the diagnosis of discitis indicates that skinny needle aspiration biopsy has a very high false-negative rate. A negative skinny-needle biopsy, therefore, must be followed by a procedure to obtain a better sample of pathologic material. Automated disc aspiration, because of its safety and ability to provide a large specimen, is the procedure of choice. Attention, however, must be paid to technical details of the procedure and the poor annular integrity of the infected disc to carry out the procedure safely.

Three-dimensional prostate ultrasound and its application to cryosurgery.

Transrectal ultrasound (TRUS), despite its undeniable utility in prostate imaging, employs a spatially flexible and variable 2-dimensional (2-D) imaging technique to visualize a 3-dimensional (3-D) disease process and anatomy. To circumvent some of the limitations of 2-D TRUS, 3-D TRUS was developed. The system consists of a motorized assembly (to hold a standard ultrasound transducer) and a computer with a video frame grabber. The microcomputer, using software developed in our laboratory, rapidly reconstructs a series of linear ultrasound images into a 3-D image. The 3-D TRUS technology has been incorporated into our program for cryoablation of the prostate. With intraoperative 3-D TRUS providing a unique coronal view, cryoprobe placement is facilitated to detect malalignment and avoid subsequent suboptimal cryoablation. In our use of 3-D TRUS guidance, in all 21 initial patients, probe malalignment, otherwise not apparent on standard 2-D TRUS, was detected and corrected before cryosurgery. With median follow-up of just < 1 year, only 2 of 44 biopsy cores (from the same site of 1 patient) were positive at 3 and 6 months. 3-D TRUS appears to be a valuable adjunctive tool in prostate imaging, especially in providing guidance for cryoblation of prostate cancer.

US-guided percutaneous cryoablation of prostate cancer.

A tailored approach to cryosurgery of prostate cancer is presented. The authors have performed 214 cryoprocedures to date with use of this protocol. The technique requires pretreatment with androgen ablation therapy, preoperative diagnosis and staging with ultrasound (US)-guided biopsies, and detailed knowledge of prostate and rectal anatomy. Five cryoprobes are placed in the prostate under US guidance in a configuration that depends on tumor location, sites of extracapsular extension, the size of the tumor, and gland geometry. Freezing starts anteriorly to keep from obstructing the ultrasound beam. Two freezes are performed at the known cancer site, and additional freezes are performed, if necessary, to include the remainder of the gland. Thermosensors enable monitoring of the cryosurgical ice ball and determination of the number of freezes. Cryosurgery is always performed by a urologist and a radiologist working together.

Transrectal ultrasound-guided percutaneous radical cryosurgical ablation of the prostate.

BACKGROUND: The two major treatments for prostate cancer, radical prostatectomy and radiation therapy, are associated with considerable morbidity and variable results. This article presents the preliminary results using percutaneous radical cryosurgical ablation under ultrasound guidance to treat prostate cancer. METHODS: The patient group consisted of all patients with localized prostate cancer who underwent cryosurgery between June 1, 1990 and May 1, 1992. Patients in Group 1 were treated by freezing of the tumor with two cryoprobes placed multiple times. Group 2 patients were treated by freezing of the tumor with five cryoprobes placed simultaneously. Cryoprobes (3 mm in diameter) were placed percutaneously with a transperineal approach. Cryoprobe placement and freezing were monitored using the transrectal ultrasound. RESULTS: Of the 55 patients (68 procedures) undergoing treatment, 23 have 3 months of follow-up with associated biopsy (Group 1, 8 patients; Group 2, 15 patients). In Group 1, three (37.5%) patients had residual disease. In Group 2, one (6.7%) patient had residual disease, whereas 14 (93.3%) patients did not. Combining both groups, 19 (82.6%) patients had no residual disease, whereas 4 (17.4%) patients had positive results on postoperative biopsy. Complications included rectal freezing, urethrorectal fistula, sloughing urethral tissue, impotence, perineal ecchymosis, penile edema, and ileus. CONCLUSIONS: Preliminary results indicate that percutaneous transperineal ultrasound-guided prostate cryosurgery may be an effective treatment for prostate cancer with minimal associated morbidity.

Ultrasound characteristics of renal cryosurgery.

The ability to visualize renal cryosurgery using ultrasound was tested in an animal model. Five dogs underwent open laparotomy and ultrasound-monitored cryosurgery of both kidneys. On each kidney two cryolesions were made. The borders of the frozen region were identified on ultrasound as a hyperechoic rim created by the interface between frozen and unfrozen tissue. The thawed cryolesion appeared hyperechoic compared with the unfrozen kidney. Excellent correlation between the ultrasound and autopsy measurements of the cryolesions was obtained. Knowing this, renal cryosurgery under ultrasound monitoring may be possible.

Cryosurgery of liver cancer.

Cryosurgery, the in situ destruction of tissue using subzero temperatures, has been used to treat hepatic metastases. Because it is a focal treatment, cryosurgery can be used in patients with unresectable lesions due to location (next to major blood vessels) or multiplicity. In this study, 57 patients with unresectable hepatic metastases were treated with cryosurgery (with at least a 6-month follow-up). The number of lesions treated ranged from 1-16 with a mean of 4.6. Forty-three patients (73%) had bilobar disease, while 25 patients (42%) were treated with a combination of resection and cryosurgery. The disease-free survival rate (patients with normal computed tomography [CT] scans and carcinoembryonic antigen [CEA] levels) was 27% with a mean follow-up of 21 months. This is comparable to other hepatic cryosurgery studies that have found survival rates of 25-37.5%. Although the results are still short-term, this study indicates that hepatic cryosurgery offers the hope of long-term survival in patients with unresectable hepatic metastases.

Monitoring cryosurgery in the brain and in the prostate with proton NMR.

This brief communication reports the results of preliminary studies performed to evaluate the feasibility of using NMR imaging to monitor the freezing of tissue during cryosurgery. Two tissues were studied, rabbit brain and dog prostate. NMR imaging of these tissues provided a clear distinction between frozen and unfrozen tissue and an accurate assessment of the extent of freezing in real time.

Hepatic cryosurgery with and without the Bair Hugger.

Hypothermia is a significant clinical problem during hepatic cryosurgery, which at times causes the procedure to be halted until the patient's body temperature can be raised. This study examines the effects of the Bair Hugger (a warming device) on body temperature during hepatic cryosurgery. Twenty-eight cases of hepatic cryosurgery were performed without the Bair Hugger, while 44 cases included the Bair Hugger. The lowest mean temperature was significantly lower in the group without the Bair Hugger (34.2 degrees C vs. 35.3 degrees C; P < 0.0001). In addition, this group showed a significantly greater mean change in temperature during the procedure (1.81 degrees C vs. 0.73 degrees C; P < 0.0001). No patient in the Bair Hugger group reached the point of clinically significant hypothermia. In conclusion, the Bair Hugger is safe and very effective in regulating body temperature and it is an essential piece of equipment performing hepatic cryosurgery.

Percutaneous discectomy for lumbar disc herniation.

Percutaneous discectomy for lumbar disc herniation is a well established, low-risk procedure effective in 70% to 80% of appropriately selected patients. Advantages include the use of local anesthesia, minimal tissue disruption, no epidural fibrosis or scarring, and negligible biomechanical effect. The risk of automated percutaneous lumbar discectomy is significantly less than that of traditional surgery.