Semiquantitative imaging measurement of baseline and vasomodulated normal prostatic blood flow using sildenafil.

The physiologic variability of blood flow to the prostate has not been studied until this time. We report the vasoactive effects of sildenafil and phenylephrine on blood flow of the normal prostate. Sildenafil increases prostate blood flow by approximately 75% and phenylephrine reduces the flow incrementally. Administration of these drugs with dynamic contrast-enhanced magnetic resonance imaging may improve the diagnosis of cancerous tissue because according to the literature, tumor angiogenic vessels lack the vasoactive physiologic response of the normal tissue.

Local carboplatin delivery and tissue distribution in livers after radiofrequency ablation.

This study investigated the local drug pharmacokinetics of intralesional drug delivery after radiofrequency ablation of the liver. We hypothesized that the tissue architecture damaged by the ablation process facilitates the drug penetration in the liver and potentially enlarges the therapeutic margin in the local treatment of cancer. The delivery rate and tissue distribution of carboplatin, an anticancer agent, released from poly(D,L-lactide-co-glycolide) implants into rat livers after radiofrequency ablation were quantified by atomic absorption spectroscopy. Results showed that carboplatin clearance through blood perfusion was significantly slower in the ablated livers, leading to a more extensive tissue retention and distribution of the drug. The concentration of Pt at the implant-tissue interface ranged from 234 to 1440 microg Pt/(g liver) in the ablated livers over 144 h versus 56 to 177 microg Pt/(g liver) in the normal tissue. The maximum penetration distance at which Pt level reached above 6 microg/g (calculated based on a reported IC90 value for carboplatin) was 8-10 mm and 4-6 mm in ablated and normal liver, respectively. Histological analysis of the necrotic lesions showed widespread destruction of tissue structure and vasculature, supporting the initial hypothesis. This study demonstrated that intralesional drug delivery could provide a sustained, elevated concentration of anticancer drug at the ablation boundary that has the potential to eliminate residual cancer cells surviving radiofrequency ablation.

Intracavitary urokinase for enhancement of percutaneous abscess drainage: phase II trial.

OBJECTIVE: To evaluate the effectiveness of urokinase as an abscess-cavity irrigant during percutaneous abscess drainage. SUBJECTS AND METHODS: In a prospective study, approved by the Food and Drug Administration and the review board at our institution, urokinase and saline were used as abscess-cavity irrigants. In the study group of 42 patients, half the patients were randomly placed into the urokinase group and the other half were placed into the control saline group. Doses used varied with the size of the abscess. Data collected from patient charts were evaluated with standard statistical methods. RESULTS: The results indicate definite benefits of the urokinase treatment. The length of stay (p = 0.0025) and treatment costs (p = 0.0021) were significantly less for the urokinase group. Other clinical parameters, including the febrile course, elevated WBC, and days of drainage, trended in a favorable fashion. CONCLUSION: Urokinase injected intracavitarily is an effective technique for shortening the treatment time and improves the clinical course for patients treated with percutaneous drainage techniques.

Complications of "dropped" gallstones after laparoscopic cholecystectomy: technical considerations and imaging findings.

New laparoscopic techniques have revolutionized the practice of surgery. Laparoscopic cholecystectomy has become one of the most commonly performed surgeries worldwide. Although shorter hospital stays and patient comfort have offered clear advantages over open cholecystectomy, the technique has resulted in several specific complications, including bile duct injury and gallbladder perforation. Although rarely clinically significant, intraperitoneal gallstone spillage can cause abscess formation and adhesions. Although these patients can present with a confusing clinical picture, their characteristic radiologic features should be recognized. We present two cases of complicated intraperitoneal gallstone spillage radiologically diagnosed and treated with laparoscopic and interventional radiologic techniques.

MR imaging-guided radio-frequency thermal ablation in the pancreas in a porcine model with a modified clinical C-arm system.

PURPOSE: To test the hypotheses that (a) magnetic resonance (MR) imaging-guided radio-frequency (RF) thermal ablation in the pancreas is safe and feasible in a porcine model and (b) induced thermal lesion size can be predicted with MR imaging monitoring. MATERIALS AND METHODS: MR imaging-guided RF ablation was performed in the pancreas of six pigs. A 17-gauge monopolar RF probe was inserted into the pancreas with MR imaging guidance, and RF was applied for 10 minutes. After postprocedural imaging (T2-weighted, short inversion time inversion-recovery [STIR], and T1-weighted imaging before and after intravenous administration of gadodiamide), the pigs were observed for 7 days and follow-up MR images were acquired. The pigs were sacrificed, and pathologic examination was performed. RESULTS: Successful RF probe placement was accomplished in all pigs; the interventional procedure took 46-80 minutes. Thermal lesions were 12-15 mm perpendicular to the probe track and were best seen on STIR and contrast material-enhanced T1-weighted images with a radiologic and/or pathologic mean difference in RF lesion diameter of 1.7 mm +/- 1.0 (SD) and 0.8 mm +/- 1.2, respectively. Diarrhea was the only side effect during the 1-week follow-up; no clinical signs of pancreatitis occurred. CONCLUSION: MR imaging-guided RF thermal ablation in the pancreas is feasible and safe. Induced thermal lesion size can best be monitored with STIR and contrast-enhanced T1-weighted images. In the future, RF ablation may offer an alternative treatment option for pancreatic cancer.

Complications of no biopsy.

OBJECTIVE: We present three cases in which complications occurred after CT-guided procedures were not carried out, supporting the contention that some complications occurring after CT-guided procedures may not be true procedural complications. CONCLUSION: Although most complications after CT-guided procedures are indeed caused by the antecedent procedure, some complications may be unrelated to the procedure and may in fact occur without any procedure being performed at all.

Interactive MR imaging-guided biopsy and aspiration with a modified clinical C-arm system.

OBJECTIVE: This investigation was performed to test the hypotheses that interactive guidance of MR image acquisition during needle-directed procedures using a clinical 0.2-T C-arm open MR imaging system integrated with a frameless optically linked stereotaxy system is feasible, and that procedure times can be sufficiently short to be well tolerated by the patient. SUBJECTS AND METHODS: One hundred six MR-guided procedures were performed in 86 patients (ranging in age from 5 months to 88 years) using a clinical C-arm imaging system supplemented with an in-room RF-shielded liquid crystal display monitor, a frameless stereotaxy system, rapid gradient-echo sequences for needle guidance, and MR-compatible monitoring and surgical lighting equipment. We performed 50 biopsies and aspirations of the head and neck in 37 patients, 23 biopsies of musculoskeletal lesions in 22 patients, 16 biopsies of abdominal sites in 10 patients, six biopsies of the thoracolumbar spine or sacrum in six patients, and 11 shoulder joint injections for MR arthrography in 11 patients, in addition to 38 MR arthrographic injections on the same imaging system described in a previous report. Tissue sampling included fine-needle aspiration (n = 90) and cutting needle core biopsy (n = 41). Thirty-five patients underwent both procedures. Procedures were evaluated for success of needle placement, procedure time, and complications. RESULTS: Needle placement was successful in all cases, and no complications occurred. Tissue was sufficient for pathologic diagnosis for all but eight patients. Passes per patient averaged 2.1. For fine-needle aspiration, instrument time averaged 7 min 42 sec per pass, cutting needle core biopsy averaged 6 min 24 sec, and shoulder injection averaged 8 min. CONCLUSION: MR imaging guidance for needle procedures on a clinical 0.2-T C-arm system with supplemental interventional accessories is feasible, with relatively rapid needle placement.

MR monitoring of MR-guided radiofrequency thermal ablation of normal liver in an animal model.

The purpose of this study was to determine the suitability of MRI to accurately detect radiofrequency (RF) thermoablative lesions created under MR guidance. In vivo RF lesions were created in the livers of six New Zealand White rabbits using a 2-mm-diameter titanium alloy RF electrode with a 20-mm exposed tip and a 50-W RF generator. This was performed using a 0.2T clinical C-arm MR imager for guidance and monitoring. Each animal was sacrificed and gross evaluation was performed. Histologic correlation was performed on the first two animals. The MR-compatible RF electrode was easily identified on rapid gradient-echo images used to guide electrode placement. A single lesion was created in each rabbit liver. Lesions ranged from approximately 10 to 17 mm in diameter (mean, 13.5 mm). T2-weighted and short T1 inversion recovery (STIR) images demonstrated lesions ranging in diameter from 12 to 18 mm (mean, 14.6 mm). Lesion dimensions determined from images closely correlated with those determined at gross examination with the discrepancy never exceeding 2 mm, for an r2 value of .87. MRI performed at the time of MR-guided RF ablation accurately demonstrated created lesions. This modality may provide a new option for the treatment of local and regional neoplastic disease.

Interactive MRI-guided radiofrequency interstitial thermal ablation of abdominal tumors: clinical trial for evaluation of safety and feasibility.

This clinical trial was performed to evaluate the safety and feasibility of interactive MR-guided radiofrequency (RF) interstitial thermal ablation (ITA) performed entirely within the MR imager. RF-ITA was performed on 11 intra-abdominal metastatic tumors during 13 sessions. The RF electrode was placed under MR guidance on a .2-T system using rapid fast imaging with steady state precession (FISP) and true FISP images. A custom 17-gauge electrode was used and was modified in four sessions to allow circulation of iced saline for cooling during ablation. Tissue necrosis monitoring and electrode repositioning were based on rapid T2-weighted and short-inversion-time inversion recovery (STIR) sequences. Morbidity and toxicity were assessed by clinical and imaging criteria. The region of tissue destruction was visible in all 11 tumors treated, as confirmed on subsequent contrast-enhanced images. No significant morbidity was noted, and patient discomfort was minimal. In conclusion, interactive MR-guided RF-ITA is feasible on a clinical .2-T C-arm system with supplemental interventional accessories with only minor patient morbidity. The ability to completely ablate tumors with RF-ITA depends on tumor size and vascularity.

Metastases to the pancreas.

Disparity in prognosis and management between primary and secondary pancreatic tumours makes recognition of metastases to the pancreas on CT and MRI an important goal. Three different patterns of secondary pancreatic tumours may be seen: localized, multifocal, or diffuse enlargement. CT findings include hypodense lesions, which show rim enhancement following intravenous contrast medium. On MR examination, the lesions are usually hypointense on T1 weighted and hyperintense on T2 weighted images.

Multifocal hepatic lesions in AIDS: an unusual presentation of steatosis.

Patients infected with HIV frequently have abnormal results on liver tests, leading to radiographic evaluation for hepatic lesions. The etiology of these lesions in patients infected with HIV is most often secondary to infections or tumors. Occasionally, focal abnormalities in the liver are identified in asymptomatic patients. The etiology and clinical course in this subset of patients are not known. However, because of concerns of tumor, an evaluation is usually warranted. We report an unusual case of multifocal hepatic steatosis presenting as multiple liver lesions in an HIV-positive patient with cutaneous Kaposi's sarcoma. This case emphasizes the importance of obtaining a tissue diagnosis in this patient population.

Liver biopsy: effects of biopsy needle caliber on bleeding and tissue recovery.

PURPOSE: To evaluate different-caliber biopsy cutting needles in terms of the benefits and potential risk of bleeding in a swine model. MATERIALS AND METHODS: A total of 190 sequential liver biopsy specimens were obtained in 11 Yorkshire pigs (weight, 50-70 lb [22.5-31.5 kg]) by using 14-, 18-, and 20-gauge cutting needles. For each biopsy procedure, blood loss was determined by weighing sponges used to absorb bleeding, and sample-tissue DNA content was measured with spectrofluorometry. Analysis of variance was used to compare results. RESULTS: The larger the caliber of needle, the greater the absolute blood loss (for 14-gauge, 1.69 g; for 18-gauge, 0.74 g; for 20-gauge, 0.32 g) and DNA content per sample (for 14 gauge, 40.38 microg; for 18-gauge, 12.18 microg; for 20-gauge, 5.86 microg). The ratio of blood loss to amount of DNA recovered did not differ among the different-caliber needles. To obtain the same amount of diagnostic tissue, more passes were needed with the smaller-caliber needles. CONCLUSION: Use of larger-caliber needles is more efficient despite the greater amount of blood loss, because more tissue can be recovered and because fewer passes are necessary, which reduces the chances of complications.

Needle localization in MR-guided biopsy and aspiration: effects of field strength, sequence design, and magnetic field orientation.

OBJECTIVE: The purpose of this investigation was to evaluate the accuracy of MR Imaging for needle depiction at 0.2 and 1.5 T with multiple pulse sequences and needle orientations. The goal was to provide a framework for biopsy approach and imaging technique parameter selection that will ensure the safety and accuracy of MR-guided procedures. MATERIALS AND METHODS: Eight titanium and stainless steel alloy MR-compatible biopsy devices were immersed in fluid phantoms and placed into 1.5- and 0.2-T MR systems used for clinical imaging. Spin-echo, turbo spin-echo, and gradient-echo images were obtained with the needle shafts of the biopsy devices placed parallel to, perpendicular to, and at angles of 30 degrees and 60 degrees relative to the static magnetic field of the scanner. All images were obtained with the frequency-encoding direction parallel to and perpendicular to the needle shaft. Needle width and tip position were measured from images on a freestanding workstation, and the apparent tip position was compared with that obtained by direct measurement. The difference between these values was calculated for each needle type, imaging sequence, frequency-encoding direction, and needle orientation. RESULTS: Artifactual widening was much more apparent at 1.5 T than at 0.2 T, as was error in determining needle tip position. Artifacts at both field strengths were most pronounced with gradient-echo sequences, less so with turbo spin-echo sequences, and least of all with spin-echo sequences. For spin-echo and turbo spin-echo sequences, when the frequency-encoding axis was perpendicular to the needle shaft, the apparent width of the needle was larger, but error in needle tip position was smaller. Artifacts were much less apparent, but error in tip position increased, as the orientation of the needle shaft became more parallel to the direction of the magnetic field. CONCLUSION: Specific measurements differed with field strength, but needle tip localization within 1 mm was obtained at both 0.2 and 1.5 T with the appropriate frequency-encoding direction, pulse sequence, and imaging parameters. Orientation of the needle parallel to the magnetic field significantly reduced the apparent width of the needle at both field strengths but also decreased the accuracy of needle tip position localization.

Modulation of O6-alkylguanine alkyltransferase-directed DNA repair in metastatic colon cancers.

PURPOSE: Carmustine (BCNU) resistance has been correlated with tumor expression of the DNA repair enzyme O6-alkylguanine-DNA alkyltransferase (AT). It has been shown that streptozotocin will deplete AT activity of human colon cancer cells in vitro and potentiate BCNU cytotoxicity. This clinical trial was conducted to determine whether streptozotocin can be used as a modulator of AT in metastatic colorectal cancers and thereby overcome clinical resistance to BCNU. PATIENTS AND METHODS: Fifteen patients with fluorouracil-resistant metastatic colon or rectal cancers were treated sequentially with 2 g/m2 of streptozotocin followed 5 1/2 hours later by BCNU. Sequential biopsies of metastases before and after streptozotocin were conducted to determine whether streptozotocin depletes tumor AT. Peripheral-blood mononuclear cells (PBMCs) were evaluated as a surrogate tissue for prediction of baseline AT levels and streptozotocin posttreatment modulation of the AT in metastases. RESULTS: Streptozotocin treatment led to a 78% (range, 69% to 89%) decrease in the AT levels in colon cancer metastases; however, myelosuppression and hepatic toxicity limited the BCNU dose to 130 mg/m2. A similar decrease in AT levels of PBMCs was found; however, the absolute levels of AT in PBMCs at baseline and following streptozotocin were not predictive of the levels expressed in metastases from the same patient. Despite the decrease in tumor levels of AT, no clinical responses were observed. CONCLUSION: Streptozotocin decreases but does not fully deplete AT activity in metastatic colorectal cancers and the residual AT level in metastases is sufficient to maintain clinical resistance to BCNU. We have also demonstrated that sequential computed tomography (CT)-directed biopsies of colorectal cancer metastases can be used to evaluate strategies to investigate modulators of AT-directed repair. AT levels of PBMCs do not predict for the AT level or degree of modulation achieved in the metastatic tumor.

Use of fibrinolytic agents to coat wire implants to decrease infection. An animal model.

RATIONALE AND OBJECTIVES: Infection is a serious complication of metallic prosthesis implantation and may necessitate removal of the prosthesis. This study uses an animal model to evaluate the effects of coating stainless steel wire implants with fibrinolytic agents to prevent infection after bacterial contamination. METHODS: Three types of steel wire implants were used: plain stainless steel, heparin-coated steel, and urokinase-heparin-coated steel. Wire implants were incubated in a known concentration of Staphylococcus epidermidis and placed into the subcutaneous tissues of three groups of anesthetized hamsters. The implants and surrounding tissues were excised after 1 week and submitted for quantitative cultures. RESULTS: Using 100 organisms as the upper allowable limit to categorize abscesses as noninfected, the following rates of noninfectivity were observed: group 1 (control), 0% noninfected; group 2 (heparin-coated wire), 40% noninfected; and group 3 (urokinase-heparin-coated wire), 50% noninfected. The noninfectivity rates of groups 2 and 3 were significantly higher than the rate of group 1 (P < 0.001). There was no significant difference between groups 2 and 3 (P = 0.19). CONCLUSIONS: Both the heparin-coated and urokinase-heparin-coated wire exhibited significantly decreased infection rates compared with uncoated wire; the heparin coating may inhibit bacterial adherence. The urokinase coating of the heparin-coated wire appears to further decrease the infection rate, but not to a statistically significant degree.

Young Investigator Award. In vivo treatment of infected prosthetic graft material with urokinase: an animal model.

PURPOSE: Pyogenic infection of vascular grafts represents a serious complication that may necessitate graft removal. If better treatment methods could be developed, perhaps some infected grafts could be salvaged and not removed. This study reports an animal model that evaluates the sterilization of contaminated vascular graft material implants with urokinase and antibiotics. MATERIALS AND METHODS: Polytetrafluoroethylene (PTFE) implants were incubated overnight in a known concentration of bacteria (Staphylococcus epidermidis) and were then implanted subcutaneously into four groups of anesthetized hamsters. The first group (control) received no treatment. The second group received urokinase injections twice daily into each abscess. The third group received intraabscess urokinase and systemic gentamicin twice daily. The fourth group received only systemic gentamicin. The hamsters were killed after 1 week. The graft implants and surrounding tissues were excised and submitted for quantitative cultures. RESULTS: With use of a cutoff value of 100 organisms per milliliter, below which the abscesses were considered noninfected, the following rates of noninfectivity were observed: group 1 (control), 5% noninfected; group 2 (urokinase only), 19.4%; group 3 (urokinase and gentamicin), 63.2%; and group 4 (gentamicin only), 32.5%. The noninfectivity rate of group 3 was significantly higher than that of all other groups combined (P < .001) and was significantly better than that of group 4 alone (P = .013). CONCLUSION: The combination of intraabscess urokinase and systemic gentamicin is very synergistic in graft sterilization. Urokinase may assist in the degradation of both fibrin and the biofilm produced by S epidermidis, thus improving penetration of antibiotics and local host defense mechanisms.