| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Vascular and Interventional Radiology |
1 From the Depts of Radiology (J.S.L., S.G.N., J.L.D., J.R.H.), Oncology (J.S.L., C.F.C.), Urology (A.S., M.I.R.), and Biomedical Engineering (J.L.D.), Case Western Reserve University, Cleveland, Ohio. From the 2001 RSNA scientific assembly. Received Oct 21, 2002; revision requested Jan 6, 2003; final revision received Dec 22; accepted Jan 16, 2004. Supported in part through research collaborations with Siemens Medical Systems and Radionics; grants from Whitaker Foundation and American Cancer Society; and grants M01RR0008040, 1R33-CA81431–01A1, and 1R01-CA84433–01 from the NIH. Address correspondence to J.S.L., Dept of Radiology, Johns Hopkins Hospital, 600 N. Wolfe St, Baltimore, MD 21287 (e-mail: jlewin2@jhmi.edu).
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
MATERIALS AND METHODS: Ten male patients (age range, 25–83 years) with peripheral renal cell carcinoma and contraindications to surgery were treated with percutaneous RF ITA entirely guided and monitored with a 0.2-T MR imaging unit. By using a 200-W RF ablation system and custom-fabricated MR imaging–compatible cool-tip electrodes, pulsed RF current was applied for single or multiple ablation cycle(s) of 12–15 minutes until the entire tumor was replaced by an enlarging zone of low signal intensity on T2-weighted and/or short inversion time inversion-recovery images acquired intermittently during the procedure. Kidney MR images were acquired before, immediately after, and 2 weeks after ablation and then every 3 months for 1 year and every 6 months thereafter. Intra- and postprocedural complications were assessed with clinical evaluation of patients for pain and hemodynamic instability and evaluation of MR images for evidence of hemorrhage or other unexpected findings. Follow-up images were assessed for delayed complications such as renal ischemia, infarct, urinoma, or tumor recurrence.
RESULTS: Treated tumors ranged between 0.63 and 16.90 mL in volume and 1.0 and 3.6 cm in maximum diameter. Successful RF electrode insertion and/or repositioning into the renal mass was achieved in all cases with direct MR "fluoroscopic" guidance. Thirty ablation cycles were conducted at 21 electrode positions in the 10 procedures, and complete ablation, as defined with MR imaging, was achieved in all cases by the end of the procedure. Apart from two small self-limited perirenal hematomas, no intra- or postprocedural complications were observed. No delayed complications or tumor recurrence occurred during a mean follow-up period of 25 months ± 9.4 (standard deviation).
CONCLUSION: Although these results are preliminary, interactive MR imaging–guided RF ITA for treatment of primary renal tumors has a high success rate.
© RSNA, 2004
Index terms: Kidney, interventional procedures, 81.1269 • Kidney neoplasms, MR, 32.12141 • Magnetic resonance (MR), guidance, 81.1269 • Radiofrequency (RF) ablation, 81.1269
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
The purpose of this study was to evaluate the efficacy and safety of interactive MR imaging–guided radiofrequency (RF) ITA of primary renal tumors.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
|
Results of histologic analysis after biopsy revealed three clear cell carcinomas, two papillary carcinomas, two oncocytic tumors, and one unclassified adenocarcinoma. The specific disease type was inconclusive in one patient owing to tumor necrosis. No patients had metastatic disease at the time of treatment. One patient had renal cell carcinoma in the setting of von Hippel-Lindau disease; the remainder of the tumors were sporadic.
MR Imaging System
MR imaging guidance and monitoring for RF ITA was achieved by using a clinical 0.2-T C-arm imaging system (Magnetom Open; Siemens Medical Solutions, Erlangen, Germany), supplemented with interventional hardware (Fig 2) and software accessories, including the following: (a) an in-room 1024 x 1280-pixel RF-shielded liquid crystal monitor, (b) an in-room MR-compatible mouse and foot pedals for controlling the MR imaging unit, and (c) rapid gradient-echo sequences for producing images for near–real-time procedure guidance.
|
RF ITA Procedures
Standard spin-echo T1-weighted MR images (repetition time msec/echo time msec, 440/15; number of signals acquired, five; matrix, 169 or 215 x 256; field of view, 30 x 40 or 36 x 36 cm) were acquired before and after intravenous administration of 0.2 mL per kilogram of body weight (0.1 mmol/kg) of gadopentetate dimeglumine (Magnevist; Berlex Laboratories, Wayne, NJ) or 0.2 mL/kg (0.1 mmol/kg) of gadodiamide (Omniscan; Nycomed, Princeton, NJ), and fast spin-echo T2-weighted (4000/102; number of signals acquired, four; matrix, 126 or 182 x 256; field of view, 25 x 40 or 36 x 36 cm; echo train length, seven) and fast spin-echo STIR (4200/48; number of signals acquired, three; matrix, 168 or 225 x 256; field of view, 30 x 40 or 36 x 36 cm; echo train length, seven) images were also obtained in all patients before the procedure, typically in a dedicated "planning session" performed 1 or a few days before treatment.
Tumor volumes were quantified (by J.S.L. or S.G.N.) on the fast spin-echo T2-weighted MR images by measuring the maximum tumor dimensions in the three orthogonal planes (ie, transverse, anteroposterior, and craniocaudal) and then calculating the volume (VOL) by using the following formula: VOL = (4
/3)(d1/2)(d2/2)(d3/2), where d1, d2, and d3 are the maximum dimensions of the tumor in the transverse, anteroposterior, and craniocaudal planes, respectively.
After intravenous sedation was induced with between 2 and 10 mg of midazolam hydrochloride (Bedford Laboratories, Bedford, Ohio) at 1 mg/mL and between 0.05 and 0.3 mg of fentanyl citrate (Abbott Laboratories, North Chicago, Ill) at 0.05 mg/mL and local anesthesia was induced with between 5 and 10 mL of an equal-volume mixture of lidocaine hydrochloride 1% (Lidocaine; Abbott Laboratories) and bupivacaine hydrochloride 0.5% (Marcaine or Bupivacaine; Abbott Laboratories) and with continuous monitoring of vital signs and blood oxygen saturation, the needle electrode was advanced (by J.S.L.) with a retroperitoneal approach into the targeted renal mass by using multiplanar MR "fluoroscopic" guidance with gradient-echo MR imaging (described below).
Gradient-echo MR imaging consisted of a continuous imaging mode allowing automated sequential acquisition, reconstruction, and in-room display of multiple sets of three contiguous parallel 5-mm sections centered on the electrode position. It took 4–15 seconds of imaging time to acquire the three contiguous sections with an adequate signal-to-noise ratio and spatial resolution (or 1.5–5.0 seconds per section in a single-section mode) (6,7). The specific technique for selecting the target imaging section position and maintaining the needle in the center of the three sections is more fully outlined in a previous report (6).
Orthogonal imaging planes oriented along the shaft of the electrode were used during this continuous imaging mode to guide insertion with respect to the three-dimensional geometry of the tumor. The sequence and parameters most commonly used were fast imaging with steady-state precession (17.8/8.1; number of signals acquired, one; flip angle, 90°; matrix, 128 x 256; field of view, 250–300 mm; section thickness, 5 mm; acquisition time, 5 seconds for 3 frames) or a form of gradient-reversed fast imaging with steady-state precession (15.2/7.4; number of signals acquired, one; flip angle, 40°) with comparable spatial parameters and an acquisition time of 14 seconds for 3 frames. The electrode position was then confirmed by using fast spin-echo sequences with either T1 weighting (500–680/24; number of signals acquired, one; echo train length, five; matrix, 250 x 256; field of view, 30–40 cm; three 5-mm-thick sections; total acquisition time, 79–106 seconds) or T2 weighting (2000/105; number of signals acquired, one to four; echo train length, 17; matrix, 238 x 256; field of view, 30–40 cm; five 5-mm-thick sections; acquisition time, 123 seconds).
Once the electrode was properly positioned within the tumor, RF ITA was performed (by J.S.L.) by depositing pulsed RF current for approximately 12–15 minutes for each electrode position. To prevent tissue charring or vaporization, the electrode was simultaneously cooled to 10°–15°C by circulating ice water through internal channels in the electrode (Fig 2) by using a pump (Radionics, Burlington, Mass).
The various ablation parameters—that is, the RF current, tissue impedance, and electrode tip temperature—were recorded (by S.G.N.) at 1-minute intervals throughout each ablation cycle. The size and shape of the developing ablation zone were directly observed (by J.S.L. and S.G.N.) as an enlarging low-signal-intensity zone surrounded by high-signal-intensity tissue reaction on fast spin-echo T2-weighted (1856/105; number of signals acquired, four; echo train length, 17; acquisition time, 92 seconds) and/or fast spin-echo STIR (2682/48; number of signals acquired, three; echo train length, seven; acquisition time, 2.5 minutes) MR images acquired intermittently during the procedure. The electrode was then repositioned with MR imaging guidance into persistent foci of intermediate- or high-signal-intensity tumor as depicted on the T2-weighted and STIR MR images. Electrode insertion and/or repositioning was considered successful when it was centered on the tumor or residual foci seen on the confirmatory orthogonal images obtained along the electrode shaft, as described above.
At the conclusion of each ablation cycle, the electrode tip temperature was observed for 2 minutes after the RF current and ice water pumping were discontinued to ensure that the tip temperature remained high enough for a sufficient amount of time to coagulate the central parts of the tumor in the vicinity of the cooled electrode. A tip temperature above 60°C for 2 minutes after ablation was considered satisfactory. Otherwise, the tumor was re-ablated (by J.S.L.) without cooling at 90°C for 2 additional minutes to ensure cell death adjacent to the electrode.
After the ablation zone was noted to encompass the entire tumor and a small cuff of normal adjacent kidney, the electrode was withdrawn and repeat fast spin-echo T2-weighted, fast spin-echo STIR, and pre- and postcontrast spin-echo T1-weighted MR imaging was performed to verify treatment results and exclude complications. The time spent from the beginning of preprocedure imaging until withdrawal of the electrode at the conclusion of ablation was calculated (by S.G.N.) for all procedures. The time spent for each electrode insertion or repositioning was also calculated (by S.G.N.). All patients were treated in a single treatment session.
Postprocedure Protocol and Patient Morbidity Assessment
After the procedure, patients were admitted to our institution’s General Clinical Research Center for 18 hours of observation. Clinical examination was performed at the time of admission and before discharge on the following day (by C.F.C.). Vital signs were recorded throughout the postprocedural observation period by a dedicated research nurse. Patients were instructed to remain supine for 6 hours and then were encouraged to ambulate. All complaints of pain or discomfort, along with any pain medications administered during the observation period by the nurse, were documented. A complete blood count was repeated before the patients were discharged.
Evidence of immediate complications was also assessed on MR images (by J.S.L.) during and immediately after ablation. Treated areas were evaluated on the immediate postablation MR images for shape, signal intensity characteristics, and evidence of hemorrhage or other unexpected abnormality. Volumetric analysis of the immediate ablation zone on fast spin-echo T2-weighted MR images was subsequently performed (by S.G.N.) by using the same ellipsoid formula used for evaluating tumor volumes before ablation.
Long-term Follow-up
Patients were seen again 2 weeks after the ablation for a detailed clinical evaluation and review of systems (by C.F.C.). They also underwent MR imaging with the same pulse sequences and acquisition parameters that had been used for preablation and immediate postablation imaging so that J.S.L. could evaluate the treated area and exclude late postprocedure complications.
Follow-up MR imaging was also performed every 3 months during the 1st year after ablation and every 6 months thereafter. The mean and the longest follow-up durations (from the procedure date to the date of the last MR imaging examination) were calculated (by S.G.N.). Once again, follow-up MR images were evaluated (by J.S.L. and S.G.N.) for ablation zone shape, signal intensity characteristics, and evidence of delayed complications such as renal ischemia, infarct, urinoma, or tumor recurrence.
Tumor recurrence was defined as the appearance of hyperintense soft-tissue signal within the ablation zone or along its margin on T2-weighted or STIR MR images or areas of abnormal contrast enhancement within the treated region on the postcontrast images. One patient chose to undergo follow-up CT rather than MR imaging owing to severe claustrophobia. For this patient, findings suspicious for recurrence at CT were defined as any contrast enhancement within the ablation zone or any increase in the size of the treated tumor. Ablation zone volumes at each of the follow-up time points were again calculated and compared by using the fast spin-echo T2-weighted MR images.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
|
In seven of the 10 patients, residual intermediate- or high-signal-intensity material was noted on the intraprocedural fast spin-echo T2-weighted and fast spin-echo STIR MR images obtained after the first ablation cycle and required up to four interactive repositionings of the RF electrode (Fig 3) and additional energy deposition during the same procedure session so that complete tumor ablation could be achieved.
|
There was no apparent relationship between the volume of the treated tumor and the number of electrode repositionings or ablation cycles required to achieve complete ablation as depicted on intraprocedural images. Two of the three tumors ablated with single electrode positions were not among the smallest tumors, while one of the two tumors requiring four electrode positions was only 1.95 mL in volume and was the third-smallest tumor in the series.
Two patients developed small perirenal hematomas that resolved spontaneously and required no treatment. No other intraprocedural complications were observed.
The mean RF current deposited during ablation was 1.0 A ± 0.3, whereas the maximum current deployed into tumor tissue during an individual ablation session was as high as 1.45 A. The mean tissue impedance recorded was 77.8 
± 22.8.
The mean procedure time, starting with acquisition of the preablation orientation images until complete tumor ablation was achieved, was calculated as approximately 3 hours ± 27 minutes (Table). The mean time required for initial electrode insertion with near–real-time MR guidance was 21 minutes, and the mean time required for each subsequent electrode repositioning, when necessary, was 10 minutes.
Patient Morbidity and Procedure Outcome
The procedure was well tolerated by all patients. During the procedure, patient discomfort was minimal and was well controlled with intravenous sedation and local anesthesia. No patient had evidence of clinically relevant bleeding. No patient experienced a delay in his discharge from the hospital because of toxicity. Four patients required mild analgesia with a single dose of oral acetaminophen (650 mg) on the evening after the procedure, while the other six patients denied discomfort and did not require any analgesia. No patient experienced constitutional symptoms, such as fever or vomiting, or changes in vital signs or blood oxygen saturation during or after the procedure. No patient required pain medication at discharge. No patient reported gross hematuria after the procedure.
Apart from the two small perirenal hematomas described above, immediate postablation MR images revealed no other complications. Ablation zones appeared on the intraprocedural and immediate postprocedural fast spin-echo T2-weighted and fast spin-echo STIR MR images as round or ovoid hypointense regions replacing the intermediate-signal-intensity or hyperintense tumors seen on preablation MR images. The hypointense thermal lesions were surrounded by a faint bright rim of inflammatory tissue reaction with well-defined inner and rather ill-defined outer borders (Figs 3, 4). Rim enhancement was noted on the postcontrast MR images obtained immediately after the ablation.
|
Long-term Follow-up Data
Excluding one patient who died of unrelated liver failure after his 1.6-month follow-up, the mean follow-up duration was 25 months ± 9.4, while the longest follow-up duration was 41.7 months.
Clinical evaluation of patients at the 2-week visit revealed consistently unremarkable findings. Follow-up fast spin-echo STIR and fast spin-echo T2-weighted MR images revealed that the thermal ablation zones continued to show the hypointensity they had shown on the intraprocedural and immediate postablation images. However, the surrounding reactive bright or enhancing rim seen on fast spin-echo T2-weighted, fast spin-echo STIR, and postcontrast MR images resolved gradually over time and was barely detectable after the 3-month examination. Additionally, the ablated adjacent perinephric fat appeared to regain its normal fat signal intensity on T2-weighted images during the follow-up period and appeared to be confined within a thin hypointense border that indicated the original extent of ablation and matched the thermal lesion size observed on the corresponding STIR MR images (Fig 5).
|
No clinical or imaging evidence of tumor recurrence or delayed complication was noted in any patient at any of the follow-up time points. The patient who died of liver cell failure showed no evidence of renal tumor recurrence at his final follow-up imaging examination 1.6 months after ablation. Postmortem autopsy evaluation was not performed in this patient.
Calculation of the volume of the ablation zones demonstrated a larger mean ablation zone volume compared with the preprocedure tumor volume, followed by gradual involution of the ablation zone over the follow-up period (Fig 6). The mean ablation zone volume at the 2-week follow-up time point reached 12.0 mL ± 5.2 (an approximately 18% increase compared with that on the immediate posttreatment images) and decreased to 5.6 mL ± 4.5 at the time of the final follow-up examination for each patient (Fig 7).
|
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
Reported complication rates for laparoscopic nephrectomy range from 8% to 35% for minor complications and from 3% to 19% for major complications. Conversion to an open procedure occurs in up to 10% of cases (14,16,17). Because of the attendant risks of the above procedures, Bosniak (18) recommended "watchful waiting" for small renal tumors in patients who are poor candidates for surgery, elderly patients, and patients with other clinically important diseases.
The natural history of small renal neoplasms is, to a great extent, favorable. Tumors smaller than 3 cm were previously classified (19) as benign adenomas but were later considered (20) to be "renal carcinomas of low metastatic potential." Such neoplasms have also been reported to grow as slowly as 0–1.3 cm per year (18) and to exhibit multicentricity in only 0%–3.7% of cases (21).
The numerous recent reports addressing successful treatment of localized hepatic malignancies by using various forms of direct interstitial thermal therapy (22–26) have stimulated investigators to search for similar successes in treating localized tumors involving other body organs, including the kidney.
Although microwave coagulation (27) and high-intensity focused ultrasound (28) have been applied to renal tissues, clinical trials for the treatment of localized renal malignancies with direct thermotherapy techniques have focused more on cryoablation (29–33) and, to a lesser extent, on RF ablation (34–37). Laser therapy has been investigated primarily in the setting of urothelial tumors (38,39) rather than in renal cell carcinomas.
Building on our preclinical data for MR imaging–guided RF ITA of the kidney in animal models (40,41) and on our experience in using the same technique in the liver and in the retroperitoneum (4), this investigation, unlike previous investigations (34–37), was, to our knowledge, the first clinical trial in which MR imaging was used to both guide and monitor the entire RF ITA procedure in primary malignant renal tumors without necessitating removal of the patient from the interventional MR suite at any time during the procedure. Near–real-time MR fluoroscopy was used to interactively direct the RF electrode into the target renal tumor and to define the treatment end point on the basis of online monitoring of the immediate MR signal intensity changes in response to tissue necrosis.
The intraprocedural and postprocedural MR signal intensity characteristics of ablation zones corresponded to those reported by previous investigators performing MR imaging–guided ITA of the liver and brain (1–5). The proved accurate correlation of these central hypointense areas with areas of actual histologic cell death (42) provided us sufficient justification to use MR imaging signal intensity changes as a reliable predictor of the treatment outcome.
The ability to detect inadequately treated parts of the tumor as persistent high-signal-intensity foci and to interactively reposition the RF electrode during therapy was critical in this investigation and enabled us to treat all our patients on a single-visit basis. This manner of controlled ablation is different from the previously reported ultrasonographic (US)- or CT-guided ablation techniques (36,37), in which the number of RF electrode insertions required to treat a given tumor was subjectively estimated according to the operator’s experience with the size and shape of the individual tumor. Not surprisingly, the finding of residual tumor at follow-up imaging that necessitates further ablation with up to a total of four visits has not been infrequent after US- and CT-guided RF ITA of kidney tumors (36).
Despite the relatively small size of the treated tumors, the use of internally cooled RF electrodes, and the application of pulsed RF current, electrode manipulation into residual untreated tumor parts was necessary in seven of our 10 patients to achieve complete tumor ablation. This relatively high proportion most likely relates to the high perfusion characteristic of renal cell carcinoma and the adjacent renal parenchyma. Likewise, the heat-sink effect resulting from this high vascularity likely explains the need for the higher RF current necessary to achieve a maximum thermal lesion size in this study as compared with the RF current previously used for liver tumor ablations (4).
In addition, although the results of this investigation are similar in many aspects to those reported for thermotherapy of liver tumors (1,4,5), ablation of renal tumors is primarily directed toward the eradication of early stage primary neoplasms and is intended to achieve complete cure rather than the palliation of metastatic disease, which is commonly the goal of liver ablations.
With regard to morbidity, patient discomfort resulting from kidney ablation is, in our experience, even less than the mild pain experienced following liver ablation. Intraprocedural discomfort was minimal and was completely controlled with intravenous sedation and local anesthesia. Only four of our 10 patients required oral acetaminophen for analgesia on the evening of treatment, while no patient required pain medication at discharge the following morning. This high patient tolerance, together with the low rate of procedural complications observed in our study and the similar experience of other investigators (37), suggest that renal RF ITA is a safe, minimally invasive, nephron-sparing treatment option with a morbidity comparable to that resulting from a simple percutaneous renal biopsy (43,44).
In addition to evaluating the feasibility and safety of RF ITA of primary renal malignancies with interactive MR imaging guidance and monitoring, this investigation was intended to enable us to estimate the treatment efficacy on the basis of both immediate and long-term follow-up data. With an average 25-month follow-up duration, none of the patients had evidence of tumor recurrence at any of their assigned follow-up time points; well-defined ablation zones continued to involute and retained their central dark signal on T2-weighted and STIR MR images, without evidence of enhancement on postcontrast T1-weighted MR images (except for the thin uniform margin—the so-called benign periablational enhancement [45]—seen at early follow-up examinations).
In the only other clinical series with a substantial length of follow-up, published by Gervais et al (36), nine renal cell carcinomas were treated with RF with either US or CT guidance. Although repeat visits were frequently necessary to achieve complete tumor ablation owing to the inherent inability of US and CT to depict the immediate effects of tissue heating, Gervais et al reported complete treatment in seven of nine tumors, with a mean follow-up period of 10.3 months.
Given the naturally slow growth rate of small renal cell carcinomas, the promising follow-up results achieved so far with percutaneous image-guided RF ITA should still be considered preliminary. No large clinical series are yet available that involve evaluation of the long-term recurrence rate, cancer-specific survival rate, or long-term patient well being after this procedure for comparison with study results already available for the more standard nephron-sparing open or laparoscopic surgery (46–49). Until such data become available, percutaneous RF ITA will be an option for patients who are not candidates for surgery because of either comorbid conditions or their vulnerability to multiple and recurrent renal cell carcinomas such as those associated with von Hippel-Lindau disease.
From a technical perspective, the results of our investigation and previous studies are sufficient to reinforce our belief that the procedure is most beneficial for small peripheral or exophytic tumors (
3–4 cm in maximum diameter) located away from the bowel loops and the urinary collecting system (so that thermal injury to these structures can be avoided) and away from the renal artery (to avoid ineffective ablation owing to the heat-sink effect of flowing blood). Interactive MR imaging guidance and monitoring will add to the efficacy of ablation primarily by enabling online feedback of the effect of tissue heating and monitoring of the growth of the ablation zone as it approaches adjacent bowel or collecting system areas and depicting untreated residual tumor.
Although no tumor recurrences were noted in our phase II trial, there were limitations to the technique with regard to both tumor size and location. The size limit in the eligibility criteria for the phase II trial had been set on the basis of results of our experimental animal trials in the kidney (40), results that suggested that there is a greater likelihood of technical failure for tumors greater than 4 cm in maximal diameter, but even tumors within this size limit may fail therapy if they are located adjacent to critical anatomic structures such as the renal pelvis or artery.
Last, nonmedical issues such as equipment availability, physician training, and cost-effectiveness of interventional MR imaging will likely influence the adoption of MR imaging for guiding and monitoring renal tumor ablations in the future, despite encouraging initial results on the contribution of MR image monitoring to the RF procedure. Although complete "interventional MR imaging suites" are currently principally available in the academic setting, an increasing number of radiology practices are gaining access to open MR imaging units. Radiologists performing RF ITA with MR imaging guidance will essentially be using the same basic skills they developed during their earlier experience with US- and CT-guided percutaneous interventions. However, they will need to acquire some knowledge of several operator-dependent parameters and needle trajectory decisions that can markedly alter needle visibility and therefore the accuracy and safety of MR imaging–guided procedures (50).
If long-term follow-up data confirm the efficacy of this procedure compared with that of conventional nephron-sparing surgery, the use of MR imaging–guided RF ITA to treat circumscribed renal malignancy may result in a remarkable cost reduction because of the lower cost of the procedure itself, as well as the diminished requirement for anesthesia and perioperative hospitalization and medication. Additionally, patients may benefit from a reduction in morbidity, mortality, and required recovery time as compared with these factors at open surgical procedures.
This report outlines the results of a phase II clinical trial of interactive MR imaging–guided RF ITA for treatment of primary renal tumors with a 25-month mean patient follow-up. Although the findings of this investigation are preliminary, the high success rate in achieving complete ablation and the absence of tumor recurrence are very encouraging. In addition, the results of this study demonstrate the contribution of MR imaging for monitoring of tumor destruction in that repositioning of the electrode and additional RF application were required in seven of 10 tumors to achieve complete ablation, despite the small size of these tumors. Further follow-up and additional patient recruitment are ongoing, and a conclusive estimate of efficacy awaits final analysis.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
Abbreviations: ITA = interstitial thermal ablation, RF = radiofrequency, STIR = short inversion time inversion recovery
Author contributions: Guarantor of integrity of entire study, J.S.L.; study concepts, J.S.L., C.F.C., J.R.H., J.L.D.; study design, J.S.L., C.F.C., J.L.D., M.I.R., J.R.H.; literature research, J.S.L., A.S., S.G.N.; clinical studies, J.S.L., C.F.C., S.G.N.; data acquisition, J.S.L., C.F.C., S.G.N., A.S., M.I.R.; data analysis/interpretation, J.S.L., S.G.N., A.S., J.L.D.; statistical analysis, S.G.N., J.S.L.; manuscript preparation and editing, J.S.L., S.G.N., C.F.C., A.S.; manuscript definition of intellectual content, J.S.L., S.G.N., C.F.C., A.S., M.I.R., J.R.H.; manuscript revision/review and final version approval, all authors
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODS RESULTS DISCUSSIONREFERENCES |
|---|
This article has been cited by other articles:
|
|
 |
|
  R. N. Uppot, S. G. Silverman, R. J. Zagoria, K. Tuncali, D. D. Childs, and D. A. Gervais Imaging-Guided Percutaneous Ablation of Renal Cell Carcinoma: A Primer of How We Do It Am. J. Roentgenol., June 1, 2009; 192(6): 1558 - 1570. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Manenti, F. Bolacchi, T. Perretta, E. Cossu, C. A. Pistolese, O. C. Buonomo, E. Bonanno, A. Orlandi, and G. Simonetti Small Breast Cancers: In Vivo Percutaneous US-guided Radiofrequency Ablation with Dedicated Cool-Tip Radiofrequency System Radiology, May 1, 2009; 251(2): 339 - 346. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. G. Nour, J. J. Derakhshan, N. J. Akhtar, M. A. Ayres, M. E. Clampitt, T. A. Stellato, and J. L. Duerk A Technique for MRI-Guided Transrectal Deep Pelvic Abscess Drainage Am. J. Roentgenol., October 1, 2008; 191(4): 1182 - 1185. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R Spendiff and A Rockall Imaging assessment of renal masses Imaging, September 1, 2008; 20(3): 205 - 214. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Sabharwal, N. Fotiadis, and A. Adam Modern trends in interventional radiology Br. Med. Bull., April 30, 2007; (2007) ldm006v1. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Kawamoto, S. Permpongkosol, D. A. Bluemke, E. K. Fishman, and S. B. Solomon Sequential Changes after Radiofrequency Ablation and Cryoablation of Renal Neoplasms: Role of CT and MR Imaging RadioGraphics, March 1, 2007; 27(2): 343 - 355. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. S. Lam, A. Breda, A. S. Belldegrun, and R. A. Figlin Evolving Principles of Surgical Management and Prognostic Factors for Outcome in Renal Cell Carcinoma J. Clin. Oncol., December 10, 2006; 24(35): 5565 - 5575. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Schraml, C. Aube, H. Graf, A. Boss, S. Clasen, T. Herberts, D. Schmidt, F. Schick, C. D. Claussen, and P. L. Pereira MR-guided Radiofrequency Ablation: Do Magnetic Fields Influence Extent of Coagulation in ex Vivo Bovine Livers? Radiology, December 1, 2006; 241(3): 746 - 752. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Teichgraber, C. Aube, D. Schmidt, E. Jehle, C. Konig, C. D. Claussen, and P. L. Pereira Percutaneous MR-guided radiofrequency ablation of recurrent sacrococcygeal chordomas. Am. J. Roentgenol., August 1, 2006; 187(2): 571 - 574. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. M. Merkle, S. G. Nour, and J. S. Lewin MR Imaging Follow-up after Percutaneous Radiofrequency Ablation of Renal Cell Carcinoma: Findings in 18 Patients during First 6 Months Radiology, June 1, 2005; 235(3): 1065 - 1071. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| RADIOLOGY | RADIOGRAPHICS | RSNA JOURNALS ONLINE |
