David D. Childs

Long-term outcomes after percutaneous radiofrequency ablation for renal cell carcinoma.

OBJECTIVES To assess the long-term oncological efficacy of radiofrequency ablation (RFA) for treatment of renal cell carcinoma (RCC). METHODS In this institutional review board-approved, retrospective study, the records and imaging studies for all RCC patients treated with percutaneous RFA before 2005 were reviewed and analyzed. RESULTS A total of 48 RCCs in 41 patients were treated with RFA. Median size of RCC treated was 2.6 cm (range: 0.7-8.2 cm). Of the 48 treated RCCs, 5 (12%) had recurrent tumor after a single ablation session. The median size of the index lesion in the cases with recurrence was 5.2 cm (interquartile range [IQR]: 4-5.3) compared with 2.2 cm (IQR: 1.7-3.1, P = .0014) without local recurrence. There were no recurrences when RCCs less than 4 cm were treated. Seventeen (41%) patients with 18 treated RCCs died during the follow-up period at a median time of 34 (IQR: 10-47) months. One patient (2%) died of metastatic RCC, whereas 16 died of unrelated causes. Twenty-four patients with 30 RCCs treated with RFA survived. For the remaining 30 RCCs, median follow up was 61 months (IQR: 54-68). No patients in this group of survivors had metastatic RCC, 1 had recurrence diagnosed at 68 months. The long-term recurrence-free survival rate was 88% after RFA. CONCLUSIONS RFA can result in durable oncological control for RCCs less than 4 cm. RFA is an effective treatment option for patients with RCCs less than 4 cm who are poor surgical candidates. For patients with larger RCCs alternative treatments should be considered.

Imaging-Guided Percutaneous Ablation of Renal Cell Carcinoma: A Primer of How We Do It

OBJECTIVE This article is a primer in conducting an imaging-guided percutaneous renal ablation program based on the clinical experience of three institutions. CONCLUSION Imaging-guided percutaneous ablation is becoming a viable alternative to surgery for the management of locally confined renal cell carcinoma. Conducting a successful renal tumor ablation program includes understanding the treatment options for early-stage renal cell carcinoma, selecting the appropriate patients, understanding the procedural techniques, and organizing a comprehensive follow-up.

MRI of Pregnancy-Related Issues: Abnormal Placentation

OBJECTIVE In this article, we review the clinical significance of abnormal placentation and the role of MRI in diagnosis and management of this potentially morbid condition. We present our clinical perspective on diagnosing this challenging problem with MRI and review the imaging findings that can lead to a correct diagnosis. CONCLUSION As abnormal placentation becomes more prevalent, in large part due to the markedly rising rates of cesarean delivery, there is a need for accurate antenatal diagnosis of this condition to prevent maternal morbidity and mortality. Maternal and fetal outcomes can be optimized through multidisciplinary planning to achieve accurate diagnosis and anticipation of the extent of abnormal placentation in the antenatal period. Imaging findings of abnormal placentation have been described for both ultrasound and MRI, although limitations exist for each technique. Although ultrasound remains the primary screening modality for the detection of abnormal placentation, MRI is a complementary technique that should be considered when ultrasound is inconclusive or incomplete. Familiarity with MRI techniques to assess the placenta, MRI appearance of normal placenta, and imaging findings that suggest abnormal placentation can help radiologists contribute to a successful maternal outcome.

Percutaneous Radiofrequency Ablation Does Not Affect Glomerular Filtration Rate

PURPOSE To study short- and intermediate-term global renal function in patients undergoing a single percutaneous radiofrequency ablation (pRFA) for a solitary renal parenchymal tumor. MATERIALS AND METHODS We reviewed the records of 62 patients who underwent a single pRFA for solitary renal parenchymal tumor. We used the abbreviated Modified Diet for Renal Disease equation to calculate baseline, 1-month, and 1-year glomerular filtration rate (GFR). We defined normal as >60, moderately diminished as 45-60, and severely diminished GFR as <45 cc/minute/1.73 m². We used the Wilcoxon paired rank sum method to compare 1-month and 1-year GFR to baseline. We fit a linear regression model to test the association of lesion size to GFR controlling for lesion location and baseline GFR. RESULTS There was no difference in GFR from baseline at 1 month or 1 year (55 vs. 58 cc/minute/1.73 m², p=0.24 and 55 vs. 57 cc/minute/1.73 m², p=0.8, respectively). Tumor size did not affect GFR at 1 month or 1 year after controlling for lesion location and baseline GFR. CONCLUSIONS A single application of pRFA does not affect GFR in the short or intermediate term.

Imaging-Guided Radiofrequency Ablation of Cystic Renal Neoplasms

OBJECTIVE The purpose of this article is to determine whether percutaneous radiofrequency ablation (RFA) is effective and safe for the treatment of cystic renal neoplasms. MATERIALS AND METHODS This is a retrospective review of imaging-guided RFA of Bosniak III and IV cysts from one institution. Thirty-eight subjects (19 men and 19 women; mean age, 71 years; age range, 46-95 years) underwent RFA of 40 cystic neoplasms (Bosniak III, n = 25; Bosniak IV, n = 15). Percutaneous biopsy was performed in 90% (36/40) of lesions. For patients with imaging follow-up of at least 1 year (n = 21), the mean duration of surveillance was 2.8 years (range, 1-6.5 years). The electronic medical record was reviewed for complications related to the procedure. Estimated glomerular filtration rate (GFR) was measured before RFA and at the last follow-up visit more than 6 months after the RFA session. RESULTS According to percutaneous biopsy, 61.1% (22/36) of lesions were malignant, and 38.9% (14/36) of biopsies were inconclusive. There was no local tumor progression, and no subjects developed metastatic disease. One subject developed a new solid renal mass during the course of follow-up. Minor complications occurred in 5.3% (2/38) of ablations and included dysuria and mild hydronephrosis related to a blood clot in the ureter. There was one major complication (2.6%), a case of flash pulmonary edema. On average, estimated GFR decreased by 2.5 mL/min/1.73 m(2). CONCLUSION Imaging-guided RFA is an effective and safe treatment of Bosniak III and IV cystic renal neoplasms with outcomes comparable to those of surgical therapies.

In-phase signal intensity loss in solid renal masses on dual-echo gradient-echo MRI: association with malignancy and pathologic classification.

OBJECTIVE The purposes of this study were to determine the prevalence of in-phase signal intensity loss on dual-echo gradient-echo MRI in solid renal masses using visual and quantitative techniques and to test for any association between in-phase signal intensity loss and pathologic classification. MATERIALS AND METHODS The renal MRI studies of 177 patients (192 solid masses consisting of 166 renal cell carcinomas [RCCs], four malignant non-RCCs, and 22 benign tumors) were qualitatively reviewed by two blinded readers for visual evidence of relative in-phase signal intensity loss. For lesions without visual evidence, whole-lesion ROIs were used to attempt quantification of subtle signal intensity loss between opposed- and in-phase images (signal intensity loss index). RESULTS Visual in-phase signal intensity loss was noted in 18% of clear cell RCC, 42% of papillary RCC, and no benign lesions. There was significant correlation between malignancy and visual signal intensity loss (Fisher exact test, p = 0.0092). Visual signal intensity loss was predictive of papillary RCC over clear cell RCC (odds ratio, 5.79; p = 0.0002) in logistic regression analysis of all RCCs, controlling for size. Quantitative assessment of remaining lesions provided no additional diagnostic benefit. CONCLUSION Visible in-phase signal intensity loss is relatively common within solid renal masses and was associated with RCC and particularly papillary RCC (among all RCCs) in our population. Quantitative analysis in lesions without visible signal intensity loss was not predictive of RCC. Further work should be performed to validate the usefulness of this additional imaging parameter to help characterize renal masses and to determine the impact of this finding on imaging techniques potentially sensitive to susceptibility effects.

Update on thermal ablation of renal cell carcinoma: oncologic control, technique comparison, renal function preservation, and new modalities.

Recent studies report mid- and long-term oncologic control with thermal ablation for small renal tumors to be equivalent to surgery. Comparisons of cryoablation, radiofrequency ablation (RFA), and laparoscopic approaches to percutaneous approaches report equivalent results. Studies report little or no decrease in renal function after ablation of renal tumors. These studies support the use of percutaneous thermal ablation for treatment of small renal malignancies. Studies also report that percutaneous ablation is a safe and durable treatment of the primary tumor in stage IV patients, ultrasound guidance for percutaneous ablation can be effective, and chyluria is relatively common after RFA. Results were disappointing for newer ablation techniques, including microwave, irreversible electroporation, and high-intensity focused ultrasound. These techniques require improvements before their use in place of RFA and cryoablation. The rates of diagnostic and subtype-specific renal tumor biopsies can be improved by using both aspirate and core techniques.

Computed tomography-guided renal tumor biopsies: tumor imaging features affecting sample adequacy.

Objective The aim of this study was to derive a model that predicts when a computed tomography (CT)–guided renal tumor biopsy will be diagnostic based on the tumor’s unenhanced imaging characteristics. Methods The CT images used to guide percutaneous biopsy and the pathology reports of 276 consecutive patients undergoing renal tumor biopsy were retrospectively reviewed. The effect of tumor size, growth pattern, location, and CT attenuation on the diagnostic biopsy rate was assessed using univariate and multivariate techniques. A model was derived using logistic regression, and its discrimination was evaluated using receiver operator characteristic curves. Results The diagnostic rate for all masses was 76.8% (212/276). Univariate and multivariate analyses revealed that increasing size and solid tumor attenuation were associated with diagnostic biopsies. The model demonstrates a discrimination of 0.71. Conclusions The likelihood of a diagnostic biopsy of a solid tumor smaller than 1 cm and of any cystic tumor is significantly less than for larger solid renal tumors. The predictive model demonstrates moderate discrimination.

MRI of the pelvis: a guide to incidental findings for musculoskeletal radiologists.

Patients undergoing magnetic resonance imaging (MRI) of the pelvis for presumed musculoskeletal disease are commonly found to have abnormal imaging findings in the incidentally imaged pelvic viscera. Such incidental findings can be problematic for the musculoskeletal imager, both in terms of assigning clinical significance and determining the appropriate workup for a given abnormality. In this article we discuss the normal MRI appearance of the various pelvic organ systems as well as normal variants, emphasizing those that can mimic pathological processes. We then discuss the MRI appearance of common pathological entities encountered in these organ systems and the key imaging findings that should warrant a recommendation for further radiologic and/or clinical evaluation.