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Biomedical subjects

Stephen B Solomon

Publications and source records attributed to Stephen B Solomon.

At least 19 recordsLinked to original sources
PubMed2006

Integrated electroanatomic mapping with three-dimensional computed tomographic images for real-time guided ablations.

BACKGROUND: New ablation strategies for atrial fibrillation or nonidiopathic ventricular tachycardia are increasingly based on anatomic consideration and require the placement of ablation lesions at the correct anatomic locations. This study sought to evaluate the accuracy of the first clinically available image integration system for catheter ablation on 3-dimensional (3D) computed tomography (CT) images in real time. METHODS AND RESULTS: After midline sternotomy, 2.3-mm CT fiducial markers were attached to the epicardial surface of each cardiac chamber in 9 mongrel dogs. Detailed 3D cardiac anatomy was reconstructed from contrast-enhanced, high-resolution CT images and registered to the electroanatomic maps of each cardiac chamber. To assess accuracy, targeted ablations were performed at each of the fiducial markers guided only by the reconstructed 3D images. At autopsy, the position error was 1.9+/-0.9 mm for the right atrium, 2.7+/-1.2 mm for the right ventricle, 1.8+/-1.0 mm for the left atrium, and 2.3+/-1.1 mm for the left ventricle. To evaluate the system's guidance of more complex clinical ablation strategies, ablations of the cavotricuspid isthmus (n=4), fossa ovalis (n=4), and pulmonary veins (n=6) were performed, which resulted in position errors of 1.8+/-1.5, 2.2+/-1.3, and 2.1+/-1.2 mm, respectively. Retrospective analysis revealed that a combination of landmark registration and the target chamber surface registration resulted in <3 mm accuracy in all 4 cardiac chambers. CONCLUSIONS: Image integration with high-resolution 3D CT allows accurate placement of anatomically guided ablation lesions and can facilitate complex ablation strategies. This may provide significant advantages for anatomically based procedures such as ablation of atrial fibrillation and nonidiopathic ventricular tachycardia.

Animals↗
PubMed2006

Results of computerized tomography guided percutaneous ablation of renal masses with nondiagnostic pre-ablation pathological findings.

PURPOSE: Ablative therapy for renal masses has been criticized because the entire tumor cannot be evaluated pathologically after the procedure. Diagnosis depends on imaging findings and the results of percutaneous needle biopsies, which may be nondiagnostic in up to 21% of cases. We determined outcomes in patients undergoing ablation who had nondiagnostic biopsies at the time of the procedure. MATERIALS AND METHODS: A total of 79 patients (88 renal masses) underwent percutaneous computerized tomography guided biopsy and ablation of a renal mass under conscious sedation. Patients with nondiagnostic biopsies were identified and the medical records were reviewed retrospectively. All patients had an enhancing renal mass on preoperative computerized tomography or magnetic resonance imaging and all underwent postoperative contrast imaging to evaluate persistent viable tumor. RESULTS: A total of 19 patients (20 tumors) with nondiagnostic percutaneous biopsy (22.7% or 20 of 88) were included in the study. No serious complications occurred. Tumors were treated with frequency ablation (12) or cryoablation (7). In 17 patients (89.5%) post-procedure imaging confirmed the absence of contrast enhancement at a median followup of 27.3 months (range 3 weeks to 56 months). In 2 cases (10.5%) post-procedure imaging showed a residual renal mass or recurrence with enhancement, suggesting that the original percutaneous biopsy result was false negative. In 1 patient residual tumor was identified on initial post-ablation imaging and the patient underwent laparoscopic partial nephrectomy. In another patient recurrence was diagnosed 30 months after ablation and the patient underwent laparoscopic radical nephrectomy. Although there was a nondiagnostic percutaneous biopsy in each case, pathological findings in the subsequent surgical specimen confirmed renal cell carcinoma. CONCLUSIONS: Nondiagnostic percutaneous biopsy at renal tumor ablation does not obviate the need for standard post-procedure imaging followup. Of patients with nondiagnostic biopsies in this series 10.5% still harbored viable renal cell carcinoma after percutaneous ablation.

Adult↗
PubMed2006

Percutaneous computerized tomography guided renal cryoablation using local anesthesia: pain assessment.

PURPOSE: The administration of intravenous sedation during prone computerized tomography guided, percutaneous procedures has the potential for complications. We assessed the pain associated with computerized tomography guided, percutaneous renal cryoablation using straight local anesthesia. MATERIALS AND METHODS: Patients were treated with cryoablation probes inserted into the renal tumor under computerized tomography guidance with local anesthesia. Patients were asked to rate the pain experienced during needle placement and cryoablation using a visual 10-degree pain score scale. Sedation was given when pain was greater than 7 or when requested by the patient. Parameters assessed were cardiopulmonary complications, the need for intravenous supplementation, the pain score during the procedure and the postoperative score. RESULTS: A total of 25 patients (30 tumors) underwent a total of 26 cryoablation sessions with only local anesthesia. Mean patient age +/- SD was 67 +/- 13 years (range 33 to 88). Average tumor and ice ball size was 2.1 +/- 0.7 (range 1.1 to 4.3) and 4.1 +/- 1.0 cm (range 2.6 to 5.9), respectively. The mean dose of 1% lidocaine was 43.89 +/- 24.97 ml (range 10 to 110). All procedures were completed in an average of 68.78 +/- 20.7 minutes (range 40 to 120). Vital signs were not significantly changed during the procedure. Successful completion of percutaneous computerized tomography guided cryoablation using local anesthesia was accomplished in 22 of the 26 sessions (84.62%) without sedation. Four patients required intravenous supplementation. CONCLUSIONS: Percutaneous computerized tomography guided cryoablation for renal tumors can be performed using local anesthesia with minimal discomfort in most patients.

Adult↗
PubMed2006

Percutaneous computerized tomography guided cryoablation for localized renal cell carcinoma: factors influencing success.

PURPOSE: We evaluated the factors that influenced the initial success rate and complication rate of percutaneous computerized tomography guided cryoablation of localized renal cell carcinoma of clinical stage T1N0M0. MATERIALS AND METHODS: A total of 21 patients with a mean age of 71.5 years and a pathological diagnosis of renal cell carcinoma were treated with percutaneous computerized tomography guided cryoablation under conscious sedation on an outpatient basis. We retrospectively reviewed clinical data, tumor characteristics, techniques and results. Tumors with complete loss of contrast enhancement were considered successfully treated. RESULTS: A total of 21 patients with 23 tumors underwent 25 cryoablation sessions. The mean intraoperative computerized tomography scan tumor size was 2.1 cm (range 0.5 to 4.3) and the mean ice ball size was 4.1 cm (range 2.2 to 7.2). Of the patients 82.6% (19 of 23) had a single treatment. Patients were followed with postoperative scans of 4.6 to 18.3 months (mean 12.3). There were 2 recurrences. The rate of successful complete tumor ablation was influenced by various factors. Tumor location and size were the major determinants for achieving tumor eradication. CONCLUSIONS: Percutaneous renal cryoablation using computerized tomography imaging proved to be a successful technique for guiding probe placement and monitoring ice ball formation. Patient selection based on tumor size and location may aid in improved outcomes. Further study and followup are necessary to determine long-term oncological efficacy.

Aged↗
PubMed2006

Clinical sequelae of radiographic iceball involvement of collecting system during computed tomography-guided percutaneous renal tumor cryoablation.

OBJECTIVES: Percutaneous renal tumor cryoablation is being evaluated as a treatment option for small renal tumors. However, when tumors are located centrally, involvement of the collecting system by the radiographic iceball can occur. We reviewed our series of computed tomography (CT)-guided percutaneous renal tumor cryoablation to identify those cases in which there appeared to be involvement of the collecting system by the radiographic iceball and to determine any clinical sequelae of such involvement. METHODS: Retrospective review of the medical records identified 6 patients who had undergone CT-guided percutaneous renal tumor cryoablation with evidence of collecting system involvement. Measurements of the tumor size, size of the radiographic iceball, and the size of the immediate postprocedure "cryozone" (region of apparent treatment on contrast-enhanced CT) were obtained from the preprocedure, intraprocedure, and immediate postprocedure CT scans. Follow-up imaging was obtained beginning at 3 to 6 months. RESULTS: Six patients were identified who met the inclusion criteria and had at least 3 months of documented follow-up. Despite the apparent involvement of the collecting system during the cryoablation procedure, no patient developed clinical signs or symptoms or radiographic evidence of a urine leak or fistula formation. Furthermore, no evidence of ureteral narrowing or stricture formation has been found to date, with a mean follow-up of 167.7 days (range 90 to 288). CONCLUSIONS: We observed no clinically appreciable urine leaks despite what appeared to be obvious involvement of the collecting system by the radiographic iceball. However, care should be exercised to avoid this insult when possible until additional research has confirmed its safety.

Adult↗
PubMed2006

Percutaneous renal cryoablation.

Percutaneous renal cryoablation (PRC) has been gaining acceptance as a minimally invasive option for the treatment of patients with solid renal masses. Herein, we reviewed the historical development of PRC, relevant contemporary clinical data, and future directions of percutaneous approaches to renal masses. Early experience suggests that PRC has the potential to offer an alternative treatment for patients with small renal masses, with the advantages of decreased treatment-associated morbidity and spared renal function. Ultrasound, computed tomography, magnetic resonance imaging, and positron-emission tomography have all been explored as potential solutions to the challenges of image guidance and follow-up; distinct advantages and disadvantages of each are reviewed here. Encouraging early results regarding oncologic efficacy, rate of complications, and overall costs support the continued evaluation of PRC. Longer-term oncologic follow-up is essential if the potential application of this minimally-invasive technique to a broader spectrum of patients with renal masses is to be determined.

Cryosurgery↗
PubMed2006

Computerized tomography guided percutaneous renal cryoablation with the patient under conscious sedation: initial clinical experience.

PURPOSE: We report on our initial clinical experience with CT guided percutaneous renal cryoablation. MATERIALS AND METHODS: CT guided percutaneous renal cryoablation was performed on 27 tumors using conscious sedation in 20 patients. Eligible patients had tumors of 5 cm or less and were poor surgical candidates or otherwise warranted nephron sparing treatment. Tumors were classified as central or noncentral depending on their relationship to the renal sinus fat. During cryoablation intraoperative active ice ball formation was monitored with real-time CT imaging to ensure adequate tumor coverage. Postoperative followup imaging was obtained at regular intervals. RESULTS: Our method appears technically feasible as of the 27 cryoablations performed, only 1 complication occurred requiring blood transfusion in a patient with a large, centrally located tumor. To date we have 16 tumors in 12 patients with imaging followup of 1 month or more (mean followup 5.9 months). Mean baseline tumor size in this group was 2.5 cm with 11 small (3 cm or less) and 5 large (more than 3 cm) tumors. Of the tumors 5 were centrally located and 11 were noncentrally located. Preliminary data suggest that of the 16 cryoablated tumors 15 showed no signs of enhancement on followup. CONCLUSIONS: CT guided percutaneous renal cryoablation appears to be a feasible treatment option for small, noncentrally located renal tumors. While early results appear promising, longer followup is needed to more clearly define the role of this treatment method.

Adult↗
PubMed2006

Cost analysis of open, laparoscopic, and percutaneous treatment options for nephron-sparing surgery.

BACKGROUND AND PURPOSES: A variety of nephron-sparing options exist for the management of small renal masses. The perioperative cost of open (OPN) and laparoscopic (LPN) partial nephrectomy, laparoscopic (LCA), and CT-guided percutaneous (PCA) cryoablation was compared using a detailed computer model. PATIENTS AND METHODS: The model incorporates operative time, consumables, anesthesia, CT usage, percutaneous biopsy, hospitalization, and transfusion expenses. Starting values were derived from a retrospective review of 317 patients treated at the Johns Hopkins Medical Institutions within the past 7 years. Hypothesis testing was performed with sensitivity analysis. RESULTS: The PCA was 2.2 to 2.7 times less costly than the other options and resulted in a cost savings of $3625 to $5155 per case. For OPN, LPN, and LCA, the operative time and hospitalization accounted for 69% to 91% of the cost. In contrast, cryoprobe consumables were responsible for >70% of total cost of PCA. An OPN was 1.2x as costly as LPN and could achieve cost equivalence only with operative times of <2.8 hours or hospitalization of <3 days. An LCA was more costly than all forms of extirpative surgery if more than two cryoprobes were used. Reusing cryoprobes during LCA was always a less-costly option than adding a second cryoprobe to the procedure. The LCA was no longer cost advantageous over OPN if more than four CT scans were obtained during the first postoperative year or if local recurrence rates exceeded 23%. CONCLUSIONS: This model defines and simplifies a series of complex cost relations between the options for nephron-sparing surgery.

Costs and Cost Analysis↗
PubMed2006

Tumor ablation treatment planning coupled to robotic implementation: a feasibility study.

The technical development described herein was undertaken to create a tumor ablation treatment system that consists of a software component and a robotic hardware component. First, the software treatment planning system enables applicator placement planning before tumor ablation. For example, it allows creation of overlapping ablations with the goal of treating larger tumors. Second, the robotic hardware system allows accurate applicator placement. The combined treatment system integrates treatment planning with treatment execution by taking the coordinates dictated by the planning system and feeding them to the robotic system for implementation. The feasibility of this system was tested in two patients with large hepatic metastases that required overlapping ablations.

Aged↗
PubMed2006

Prophylactic gelatin sponge tract injection to prevent bleeding after percutaneous renal cryoablation in a swine model.

PURPOSE: Achievement of hemostasis can be a challenge during percutaneous renal cryoablation (PRC). This study describes the use of a porcine model to test the ability of gelatin sponge injection into the tract to limit bleeding at the site of cryoprobe puncture. MATERIALS AND METHODS: A total of nine swine (18 kidneys) underwent bilateral ultrasound-guided PRC with double freeze/thaw cycle protocol with use of a 2.4-mm cryoprobe. The cryoablation location and protocol were applied identically to both kidneys in each pig; however, only one side received gelatin sponge injection after cryoablation through a coaxial sheath (3 mm). After removal of the sheath, a midline laparotomy incision was performed and sponges were placed around the kidneys. Blood loss was measured by calculating the change in weight of the sponges after 30 minutes of absorption time. Acute blood loss was compared between the two groups. The kidneys treated with gelatin sponge were removed and grossly and histologically examined to identify the gelatin sponge at the puncture cryolesion. RESULTS: The use of gelatin sponge resulted in significantly less blood loss (mean, 8.24 mg +/- 4.68) compared with the control kidneys (mean, 20.24 mg +/- 8.14; P = .001). Gross and histopathologic results confirmed that the gelatin sponge was in the cryoablation puncture sites. Mean diameters of cryoablation ice balls on the gelatin sponge and control sides were 3.9 cm +/- 0.2 and 3.8 cm +/- 0.4, respectively. The lesions were not significantly different between sides. CONCLUSION: Percutaneous tract injection of gelatin sponge appears promising as a method to decrease acute blood loss from PRC.

Angioplasty, Balloon↗
PubMed2006

Trends in the operative management of renal tumors over a 14-year period.

OBJECTIVE: To review the trends in the operative management of renal tumours over a 14-year period at a university hospital, as the therapeutic options available for treating renal tumours have increased over the past decade. PATIENTS AND METHODS: The study was a retrospective chart review of 1621 consecutive patients undergoing treatment for renal tumours from January 1991 to March 2005. The characteristics assessed included patient demographics, tumour size, operative duration and treatment. RESULTS: During the study period, 624 (38.6%) open, 883 (54.6%) laparoscopic and 111 (6.7%) percutaneous approaches were performed. The number of renal tumours treated increased annually, as did the use of minimally invasive techniques (93.4% in 2005). Conversely, the number of open surgical treatments used declined both absolutely and proportionally. Over the study period, for tumours of 7 cm, open radical nephrectomy (ORN) was the most common method of treatment over all years. However, since 2002, laparoscopic radical nephrectomy (LRN) surgery has been increasingly used over ORN for treating this tumour group (73% LRN vs 19.2% ORN in 2004). CONCLUSION: The available treatment options for renal tumours have increased significantly since the early 1990s. At a university hospital in which there are physicians with a specific interest in minimally invasive surgery and ablative treatments, minimally invasive approaches have become the standard treatment.

Aged↗
PubMed2005

Pain control requirements for percutaneous ablation of renal tumors: cryoablation versus radiofrequency ablation--initial observations.

PURPOSE: To retrospectively compare the pain control requirements of patients undergoing computed tomography (CT)-guided percutaneous radiofrequency (RF) ablation with those of patients undergoing CT-guided percutaneous cryoablation of small (< or = 4-cm) renal tumors. MATERIALS AND METHODS: The study was HIPAA compliant and received institutional review board exemption; informed consent was not required. Medical and procedure records of patients who underwent RF ablation and cryoablation of renal tumors from June 19, 2003, to February 28, 2004, were retrospectively reviewed for clinical data, tumor characteristics, and anesthesia information. During the study period, 10 men (mean age, 66.5 years) underwent cryoablation of 11 renal lesions, and 14 patients (11 men, four women; mean age, 68.1 years) underwent RF ablation of 15 renal tumors. Analgesic and sedative requirements during the procedure were compared. Standard anesthesia consisted of 5 mL of 1% lidocaine injected locally, and conscious sedation consisted of 50 microg of fentanyl and 1 mg of midazolam administered intravenously. The Fisher exact test and Student t test were used to compare clinical factors and drug requirements between the two groups. RESULTS: There was no difference in terms of patient demographics, tumor diameter, or distribution of central versus noncentral lesions between the two groups. Cryoablation was associated with a significantly lower dose of fentanyl (165.0 microg [RF group] vs 75.0 microg [cryoablation group]; P < .001) and midazolam (2.9 mg [RF group] vs 1.6 mg [cryoablation group]; P = .026). In the RF group, one patient required general anesthesia, one patient required supplemental narcotics (5 mg of oxycodone) and sedatives (1 mg lorezapam), and one patient became apneic for a brief interval after receiving additional narcotics for pain during the procedure. An additional RF session was terminated early in one patient because of pain, and further medication could not be administered owing to bradycardia. No patients in the cryoablation group required any additional or alternate anesthetics. CONCLUSION: Image-guided percutaneous cryoablation of small (< or = 4-cm) renal lesions appears to require less analgesia than RF ablation. Prospective trials with validated pain scales are needed to examine this further.

Aged↗
PubMed2005

Neuromuscular complications after percutaneous radiofrequency ablation of renal tumors.

Neuromuscular complications after percutaneous renal tumor ablation have not been previously reported. In a series of 48 patients undergoing percutaneous ablation, 3 of our patients had neuromuscular complications. One patient developed permanent flank laxity and two had transient paresthesias. Neuromuscular complications are uncommon, but may occur with percutaneous renal ablative surgery.

Aged↗
PubMed2005

Imaging following cryoablation of a renal lesion.

BACKGROUND: An 81-year-old man presented with a history of right nephrectomy for renal cell carcinoma, chronic renal insufficiency and implanted defibrillator. He was asymptomatic. Contrast-enhanced CT and MRI were contraindicated. INVESTIGATIONS: Non-contrast CT, positron emission tomography (PET), fused PET-CT and Doppler ultrasound. DIAGNOSIS: Small exophytic left midpole renal tumor, 3.7 cm in size. MANAGEMENT: Percutaneous CT-guided renal cryoablation, followed up with PET-CT imaging.

Aged↗