Renal mass biopsy to guide treatment decisions for small incidental renal tumors: a cost-effectiveness analysis

Cost-Effectiveness Analysis Comparing Biopsy in Advance of Ablation with Concurrent Biopsy and Ablation for Small Renal Masses Measuring 1-3 cm

PURPOSE

To analyze the cost effectiveness of performing a renal mass biopsy in advance of ablation or concurrently with a percutaneous ablation procedure for the management of small renal masses (SRMs).

MATERIALS AND METHODS

A decision-analytic model was developed with a cohort of 65-year-old male patients with an incidental, unilateral 1-3 cm SRM. A decision tree modeled the first year of clinical intervention, after which patients entered a Markov model with a lifetime horizon. Patients were assumed to be treated in accordance with established clinical practice guidelines, including surveillance, repeat ablation for recurrence, and systemic therapy for metastasis. Healthcare cost and utility values were determined from published literature or local hospital estimates, discounted at 1.5%. Total lifetime costs were calculated from the perspective of a Canadian healthcare payer and converted to 2022 Canadian dollars (C$). The primary outcome was incremental cost-effectiveness ratio (ICER) at a willingness-to-pay threshold of C$50,000 per quality-adjusted life year (QALY) gained. The secondary outcome was ICER at a willingness-to-pay threshold of C$50,000 per life year (LY) gained.

RESULTS

Concurrent biopsy and ablation resulted in a gain of 16.4 quality-adjusted days, at an incremental cost of $386, with an ICER of C$8,494/QALY. The concurrent strategy was the dominant strategy for a prevalence of benign mass of <5%. Sequential biopsy and ablation was only cost-effective when LYs were not quality-adjusted and ablation cost was >C$4,300 or benign mass prevalence was >28%.

CONCLUSIONS

Concurrent biopsy and ablation is cost-effective relative to pretreatment diagnostic biopsy for management of incidental SRMs.

Utilization of Re-VASC, the Novel Retroperitoneal Neovascularity Scoring System, for Characterization of T1a Small Renal Masses

Purpose: Early characterization of small (T1a, <4 cm) renal masses is imperative for patient care and treatment planning. Renal biopsy is a sensitive and specific procedure that can accurately differentiate small renal masses as malignant or benign. However, it is an invasive procedure with a nonnegligible complication rate and is not performed routinely at most institutions. In this study, we sought to apply the Retroperitoneal Vascularity Assessment and Scoring in Carcinoma (Re-VASC) scoring system to T1a renal masses and analyzed whether it could differentiate these masses as benign or malignant. Methods: We obtained Institutional Review Board approval to retrospectively examine the records of all patients who presented to our single, urban academic referral center for surgical treatment of renal cell carcinoma (RCC). For the malignant group, patients with a diagnosis of T1a RCC from pathologic evaluation were included. Additionally, patients with a histopathological diagnosis of a T1a nonmalignant renal mass (fat poor-angiomyolipoma or oncocytoma) were included in our benign group. Results: This study includes 57 benign and 69 malignant T1a renal tumors. Average size for benign and malignant masses were 2.47 and 2.63, respectively (p = 0.267). Analysis demonstrated no significant difference between both groups in terms of sex, laterality, or size. The average Re-VASC score of benign and malignant masses was 0.175 and malignant masses was 0.784, respectively (p < 0.001). Additionally, the Re-VASC score was independently associated with malignancy with an odds ratio of 2.223 (p = 0.0109). Conclusion: The Re-VASC scoring system exhibits significantly greater values for malignant T1a renal masses when compared to benign masses. As a result, it shows promise as an adjunctive tool to renal biopsy for clinical decision-making. Further assessment of Re-VASC's true efficacy as a diagnostic marker will include prospective evaluation of a larger multicenter population.

Cost-effectiveness analysis: percutaneous microwave ablation vs robotic-assisted partial nephrectomy for small renal masses

PURPOSE

The majority of newly diagnosed renal tumors are masses < 4 cm in size with treatment options, including active surveillance, partial nephrectomy, and ablative therapies. The cost-effectiveness literature on the management of small renal masses (SRMs) does not account for recent advances in technology and improvements in technical expertise. We aim to perform a cost-effectiveness analysis for percutaneous microwave ablation (MWA) and robotic-assisted partial nephrectomy (RA-PN) for the treatment of SRMs.

METHODS

We created a decision analytic Markov model depicting management of the SRM incorporating costs, health utilities, and probabilities of complications and recurrence as model inputs using TreeAge. A willingness to pay (WTP) threshold of $100,000 and a lifetime horizon were used. Probabilistic and one-way sensitivity analyses were performed.

RESULTS

Percutaneous MWA was the preferred treatment modality. MWA dominated RA-PN, meaning it resulted in more quality-adjusted life years (QALYs) at a lower cost. Cost-effectiveness analysis revealed a negative Incremental Cost-Effectiveness Ratio (ICER), indicating dominance of MWA. The model revealed MWA had a mean cost of $8,507 and 12.51 QALYs. RA-PN had a mean cost of $21,521 and 12.43 QALYs. Relative preference of MWA was robust to sensitivity analysis of all other variables. Patient starting age and cost of RA-PN had the most dramatic impact on ICER.

CONCLUSION

MWA is more cost-effective for the treatment of SRM when compared with RA-PN and accounting for complication and recurrence risk.

Case Report: Robot-assisted laparoscopic nephron-sparing surgery for a renal abscess mimicking a tumor

The differential diagnosis of renal tumors and abscesses is crucial owing to their different treatments. Although antibacterial administration and radiological examination are excellent means for distinction, misdiagnosis is common and may lead to severe consequences, such as the need for nephrectomy. Here, we report a case involving a 52-year-old Asian woman with a renal mass for which a differential diagnosis was challenging. The mass persisted after administration of intravenous antibiotic therapy for 1 month. A computed tomography scan indicated an inflammatory lesion, whereas magnetic resonance imaging suggested a diagnosis of a tumor. Despite these indications, a right renal abscess was suspected during robot-assisted laparoscopic surgery, and nephron-sparing surgery was performed, which allowed confirmation of the final pathological result by biopsy specimen. Postoperatively, the mass gradually decreased in size after antibiotic therapy for a further month. This case, in which a renal abscess mimicked a tumor and the patient almost underwent a nephrectomy, highlights the need for caution in establishing therapeutic schedules for patients with inaccurate diagnoses. The management strategies for such patients must be reviewed and improved.

Two-dimensional correlated spectroscopy distinguishes clear cell renal cell carcinoma from other kidney neoplasms and non-cancer kidney

Background

Routinely used clinical scanners, such as computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound (US), are unable to distinguish between aggressive and indolent tumor subtypes in masses localized to the kidney, often leading to surgical overtreatment. The results of the current investigation demonstrate that chemical differences, detected in human kidney biopsies using two-dimensional COrrelated SpectroscopY (2D L-COSY) and evaluated using multivariate statistical analysis, can distinguish these subtypes.

Methods

One hundred and twenty-six biopsy samples from patients with a confirmed enhancing kidney mass on abdominal imaging were analyzed as part of the training set. A further forty-three samples were used for model validation. In patients undergoing radical nephrectomy, biopsies of non-cancer kidney cortical tissue were also collected as a non-cancer control group. Spectroscopy data were analyzed using multivariate statistical analysis, including principal component analysis (PCA) and orthogonal projection to latent structures with discriminant analysis (OPLS-DA), to identify biomarkers in kidney cancer tissue that was also classified using the gold-standard of histopathology.

Results

The data analysis methodology showed good separation between clear cell renal cell carcinoma (ccRCC) versus non-clear cell RCC (non-ccRCC) and non-cancer cortical tissue from the kidneys of tumor-bearing patients. Variable Importance for the Projection (VIP) values, and OPLS-DA loadings plots were used to identify chemical species that correlated significantly with the histopathological classification. Model validation resulted in the correct classification of 37/43 biopsy samples, which included the correct classification of 15/17 ccRCC biopsies, achieving an overall predictive accuracy of 86%, Those chemical markers with a VIP value >1.2 were further analyzed using univariate statistical analysis. A subgroup analysis of 47 tumor tissues arising from T1 tumors revealed distinct separation between ccRCC and non-ccRCC tissues.

Conclusions

This study provides metabolic insights that could have future diagnostic and/or clinical value. The results of this work demonstrate a clear separation between clear cell and non-ccRCC and non-cancer kidney tissue from tumor-bearing patients. The clinical translation of these results will now require the development of a one-dimensional (1D) magnetic resonance spectroscopy (MRS) protocol, for the kidney, using an in vivo clinical MRI scanner.

Value of energy spectrum CT parameters in the differential diagnosis of high-grade clear cell renal cell carcinoma and type II papillary renal cell carcinoma

BACKGROUND

Energy spectrum computed tomography (CT) has become a promising approach for the differential diagnosis of tumor subtypes.

PURPOSE

To explore the value of energy spectrum CT parameters in the differential diagnosis of high-grade clear cell renal cell carcinoma (ccRCC) and type II papillary renal cell carcinoma (pRCC).

MATERIAL AND METHODS

Forty-two cases of high-grade ccRCC and 28 cases of type II pRCC were retrospectively reviewed. All region of interest (ROI) measurements were maintained consistently between the two-phase contrast-enhanced examinations. The ROIs encompassed as much of the enhancing areas of the lesions as possible. Energy spectrum CT parameters of all cases, including the 70 keV (HU) value, normalized iodine concentration (NIC), and energy spectrum curve slope were recorded by two radiologists with over 10 years of experience in abdominal CT diagnosis.

RESULTS

In the cortical phase (CP) and parenchymal phase (PP), the 70 keV (HU) value, NIC, and slope value of the energy spectrum curve of high-grade ccRCC were significantly higher than those of type II pRCC. In the CP, NIC showed the highest differential diagnosis efficiency for the two group tumors, with a sensitivity of 78.9% and a specificity of 77.0%. There was no statistical difference in tumor hemorrhage, tumor envelope, tumor morphology, tumor border, lymph node metastasis, embolism, renal pelvis invasion, or tumor calcification between the two tumor types. However, there was significant difference in the number of tumors (P = 0.019).

CONCLUSION

Energy spectrum CT parameters are valuable for the differential diagnosis of high-grade ccRCC and type II pRCC.

Ultrasonography findings for the diagnosis of renal oncocytoma

Renal oncocytomas are rare benign epithelial tumors of the kidney. However, they are easily misdiagnosed as renal cancers, resulting in unnecessary radical nephrectomy. This review summarizes the use of ultrasound for the diagnosis of renal oncocytomas. On two-dimensional grayscale ultrasound, renal oncocytomas appear as solid, well-defined, round or oval, and relatively isoechoic or slightly hyperechoic masses. On color Doppler flow imaging, the "spoke-wheel" sign is evident. On power Doppler flow imaging, renal oncocytomas show mixed penetrating and peripheral patterns. Renal oncocytomas usually appear as highly enhanced on contrast-enhanced ultrasound images, and irregular nonenhanced areas in larger tumors. This review will help sonographers recognize renal oncocytomas.

Renal Mass Biopsy

Kidney cancer accounts for 2% of cancer related deaths. Historically, a patient with a solid renal mass would undergo surgery without biopsy given the previously low diagnostic yield of biopsy and the fear of tumor seeding. This led to a high rate of resection for benign masses. With the rising incidence of renal masses discovered on imaging, improvements in biopsy technique and advancements in pathologic evaluation of biopsy samples of renal masses, renal mass biopsy now plays an important role in selected patients with renal masses. Coaxial core needle biopsy is the preferred technique with a low rate of complications and a high diagnostic yield. This article will discuss indications, methods, utility, limitations and complications of renal mass biopsy.

Office-Based Renal Tumor Biopsy: a Paradigm Change in the Management of a Small Renal Mass?

PURPOSE OF REVIEW

The goal of this paper is to evaluate the use of an office-based renal mass biopsy (RMB), whose feasibility could represent a paradigm shift in clinical practice.

RECENT FINDINGS

Despite the earlier diagnosis of patients with renal masses, the lack of evidence showing a reduction in cancer-specific mortality warrants an examination in treatment practices. RMB is underutilized when compared to biopsy practice for all other neoplasms in every other solid organ (except testis), and the majority of RMB performed are outsourced to interventional radiologists. Performing an ultrasound-guided, office-based RMB is safe, reproducible, and has a meaningful impact on management decisions. The use of percutaneous RMB in clinical practice is growing, and the use of RMB has meaningful impact on management decisions for renal masses. Incorporating ultrasound-guided biopsy of a renal mass into clinical practice is feasible, and in contemporary practice, the urologist has the skill set to perform the procedure reliably, with low morbidity, and with minimal patient discomfort.

Can preoperative renal mass biopsy change clinical practice and reduce surgical intervention for small renal masses?

INTRODUCTION

The role of renal biopsy prior to surgical intervention for a renal mass remains controversial despite the fact that for all other urological organs except the testicle, biopsy inevitably precedes treatment as is true for all other specialties dealing with solid masses (e.g. thyroid, breast, colon, liver, etc.). Accordingly, we sought to determine the impact of a routine biopsy regimen on the course of patients with cT1a lesions in comparison with a contemporary series of cT1a individuals who went directly to treatment without a preoperative biopsy.

METHODS

We analyzed a multi-institutional, prospectively maintained database of patients who underwent an office-based, ultrasound-guided, renal mass biopsy (RMB) for a cT1a renal mass (i.e. ≤4cm in largest dimension). Controls were selected from all patients in the database who had a cT1a renal lesion but did not undergo RMB. Both groups were analyzed for differences in treatment modality and surgical pathology results.

RESULTS

A total of 72 RMB and 73 control patients were analyzed. The groups were similar in regards to their baseline characteristics. Overall RMB diagnostic rate was 75%. Surgical pathology revealed that excision of benign tumors was eight-fold less in the RMB cohort compared to the control group (3% vs. 23%; P < 0.001). Additionally, the rate of active surveillance in the RMB cohort was nearly three times higher at 35% vs. 14% for the controls (P < 0.001). Biopsy was concordant with surgical pathology in 97% of cases for primary histology (i.e. benign vs. malignant), 97% for histologic subtype, and 46% for low (I or II) vs. high (III or IV) grade. On multivariate analysis patients who underwent surgical intervention without preoperative RMB were 6.7 times more likely to have benign histopathology compared to patients who underwent preoperative RMB (OR 6.7, 95% CI = 0.714 - 63.626, P = 0.096). There were no procedural or post-procedural RMB complications.

CONCLUSIONS

For patients with cT1a lesions, the implementation of routine office-based RMB led to a significant decrease in the rate of surgical intervention for benign tumors. This practice also resulted in a higher rate of active surveillance for the management of renal cortical neoplasms with benign histopathology compared to a control group.

Renal mass biopsy: A strategy to reduce associated costs and morbidity when managing localized renal masses

INTRODUCTION AND OBJECTIVES

Renal mass biopsy (RMB) has not been widely adopted in evaluating small renal mass due to concerns for safety, efficacy, and its perceived lack of consequence on management decisions. We assess the potential cost savings and morbidity avoidance of routine RMB on cT1 renal masses undergoing robotic-assisted partial nephrectomy (RAPN).

METHODS

We identified n = 920 consecutive RAPN pT1 renal masses and n = 429 consecutive RMBs for cT1 renal masses over 12 years. Using a novel pathological-based risk classification system for cT1 renal masses, we evaluated the morbidity and costs of our RAPN and RMB cohorts. We then define four clinical scenarios where RMB could potentially delay and/or avoid intervention in our pT1 RAPN cohort and model potential complications prevented and cost savings utilizing common clinical scenarios.

RESULTS

Using our risk stratification system in RAPN patients, final histology was classified as benign in n=174 (18.9%) cases, very low-risk (n = 62 [7%]), low-risk (n = 383 [42%]), and high-risk (n = 301 [33%]), respectively. We identified n = 116 (12.6%) Clavien graded peri-operative complications. In our RMB patients, 120 (27.9%), 17 (3.9%), 240 (55.9%), 52(12.1%) were benign, very low, low and high-risk tumors. The median total direct cost for RAPN was $6955/case compared to $1312/case for RMB. If we established a primary goal to avoid immediate extirpative surgery in benign renal tumors, in the elderly (>70 y) with very low-risk tumors and/or those with high renal functional risks (≥ CKD3b), or competing risks (ASA ≥ 3), RMB could have reduced direct costs by approximately 20% and avoided n = 39 Clavien graded complications, seven readmissions, three transfusions, and two returns to the OR. With the additional cost of performing RMB on those not initially biopsied, the net cost saving would be approximately $1.2 million with minimal added complications while still treating high-risk tumors.

CONCLUSIONS

Routine RMB before intervention results in cost-saving and complication avoidance. Given the limitations of biopsy, shared decision-making is mandatory. Biopsy should be considered prior to intervention in at-risk populations.

The increasing use of renal tumor biopsy amongst Canadian urologists: When is biopsy most utilized?

INTRODUCTION

The role of renal tumor biopsy (RTB) in the management of small renal masses (SRMs) is progressively being recognized as a tool to decrease overtreatment. While an increasing number of studies assessing its role in diagnostics are becoming available, RTB remains variably used amongst urologists. Many patient-, tumor-, and institution-related factors may influence urologists on whether to perform a RTB to help guide management.

OBJECTIVE

We aimed at identifying factors associated with the use of RTB for localized SRMs within a number of centers contributing data to the Canadian Kidney Cancer information system.

MATERIAL AND METHODS

We identified 3,838 patients diagnosed with a localized SRM (≤4 cm) between January 2011 and December 2018. Patients were stratified based on whether a RTB was performed prior to the primary therapeutic intervention. Factors associated with use of RTB were assessed using univariable and multivariable logistic regression models.

RESULTS

A total of 993 patients (25.9%) underwent an RTB. There was an overall increase in RTB use over time (P < 0.001), with patients diagnosed between 2015 and 2018 undergoing more RTB than patients diagnosed between 2011 and 2014 (29.8% vs. 22.2%, respectively; P < 0.001). Patients managed in centers with the highest patient-volume had RTB more frequently than patients managed in low-volume centers. On multivariable analysis, increasing year of diagnosis was significantly associated with more RTB use. Patients treated with surgery underwent RTB statistically less often than patients undergoing thermal ablation (P < 0.001) or managed with active surveillance (P < 0.001). Larger SRMs were associated with more RTB use in patients on active surveillance (P = 0.009), but with less RTB in patients undergoing surgery (P = 0.045).

CONCLUSION

This large multicenter cohort study reveals an increasing adoption and overall use of RTB amongst Canadian urologists. Patients managed in high-volume centers and those undergoing non-surgical management were associated with greater use of RTB. Tumor size was also associated with RTB use. This study highlights the influence that physician perceptions and clinical factors may have in the decision to use RTB prior to initiating a therapeutic approach.

Asian Conference on Tumor Ablation guidelines for renal cell carcinoma

Thermal ablation has been established as an alternative treatment for renal cell carcinoma (RCC) in patients who are poor candidates for surgery. However, while American and European guidelines have been established for American and European patients, respectively, no ablation guidelines for Asian patients with RCCs have been established many years after the Asian Conference on Tumor Ablation (ACTA) had been held. Given that Western guidelines are difficult to apply to Asian patients due to differences in body habitus, economic status, and insurance systems, the current review sought to establish the first version of the ACTA guidelines for treating a RCC with thermal ablation.

Point-of-care characterization and risk-based management of oral lesions in primary dental clinics: A simulation model

OBJECTIVES

Oral potentially malignant disorders (OPMDs) encompass histologically benign, dysplastic, and cancerous lesions that are often indistinguishable by appearance and inconsistently managed. We assessed the potential impact of test-and-treat pathways enabled by a point-of-care test for OPMD characterization.

MATERIALS AND METHODS

We constructed a decision-analytic model to compare life expectancy of test-treat strategies for 60-year-old patients with OPMDs in the primary dental setting, based on a trial for a point-of-care cytopathology tool (POCOCT). Eight strategies of OPMD detection and evaluation were compared, involving deferred evaluation (no further characterization), prompt OPMD characterization using POCOCT measurements, or the commonly recommended usual care strategy of routine referral for scalpel biopsy. POCOCT pathways differed in threshold for additional intervention, including surgery for any dysplasia or malignancy, or for only moderate or severe dysplasia or cancer. Strategies with initial referral for biopsy also reflected varied treatment thresholds in current practice between surgery and surveillance of mild dysplasia. Sensitivity analysis was performed to assess the impact of variation in parameter values on model results.

RESULTS

Requisite referral for scalpel biopsy offered the highest life expectancy of 20.92 life-years compared with deferred evaluation (+0.30 life-years), though this outcome was driven by baseline assumptions of limited patient adherence to surveillance using POCOCT. POCOCT characterization and surveillance offered only 0.02 life-years less than the most biopsy-intensive strategy, while resulting in 27% fewer biopsies. When the probability of adherence to surveillance and confirmatory biopsy was ≥ 0.88, or when metastasis rates were lower than reported, POCOCT characterization extended life-years (+0.04 life-years) than prompt specialist referral.

CONCLUSION

Risk-based OPMD management through point-of-care cytology may offer a reasonable alternative to routine referral for specialist evaluation and scalpel biopsy, with far fewer biopsies. In patients who adhere to surveillance protocols, POCOCT surveillance may extend life expectancy beyond biopsy and follow up visual-tactile inspection.

ACR Appropriateness Criteria® Indeterminate Renal Mass

Renal masses are increasingly detected in asymptomatic individuals as incidental findings. CT and MRI with intravenous contrast and a dedicated multiphase protocol are the mainstays of evaluation for indeterminate renal masses. A single-phase postcontrast dual-energy CT can be useful when a dedicated multiphase renal protocol CT is not available. Contrast-enhanced ultrasound with microbubble agents is a useful alternative for characterizing renal masses, especially for patients in whom iodinated CT contrast or gadolinium-based MRI contrast is contraindicated. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The role of renal mass biopsy in the management of small renal masses – patterns of use and surgeon opinion

Aims:

Renal mass biopsy (RMB) is advocated to improve management of small renal masses, however there is concern about its clinical utility. This study aimed to elicit opinions about the role of RMB in small renal mass management from surgeons managing renal cell carcinomas (RCC), and examine the frequency of pre-treatment biopsy in those with RCC.

Methods:

All surgeons in two Australian states (Queensland: n = 59 and Victoria: n = 108) who performed nephrectomies for RCC in 2012/2013 were sent questionnaires to ascertain views about RMB. Response rates were 54% for Queensland surgeons and 38% for Victorian surgeons. We used medical records data from RCC patients to determine RMB frequency.

Results:

Most Queensland (81%) and Victorian (59%) surgeons indicated they rarely requested RMB; however 34% of Victorians reported often requesting RMB, compared with no Queensland surgeons. This was consistent with medical records data: 17.6% of Victorian patients with T1a tumours received RMB versus 6.7% of Queensland patients ( p < 0.001). Surgeons’ principal concerns regarding RMB related to sampling reliability (90%) and/or histopathological interpretation (76%).

Conclusions:

Most surgeons report infrequent use of RMB for small renal masses, however we observed practice variation. The principal reasons for infrequent use were concerns about sampling reliability and histopathological interpretation, which may be valid in regions with less access to interventional radiologists and uropathologists. Further evidence is required to define patient groups for whom biopsy results will alter management.

Level of evidence:

Not applicable for this multicentre audit.

Cost-effectiveness of dual-energy CT versus multiphasic single-energy CT and MRI for characterization of incidental indeterminate renal lesions

PURPOSE

To evaluate the cost-effectiveness of DECT versus multiphasic CT and MRI for characterizing small incidentally detected indeterminate renal lesions using a Markov Monte Carlo decision-analytic model.

BACKGROUND

Incidental renal lesions are commonly encountered due to the increasing utilization of medical imaging and the increasing prevalence of renal lesions with age. Currently recommended imaging modalities to further characterize incidental indeterminate renal lesions have some inherent drawbacks. Single-phase DECT may overcome these limitations, but its cost-effectiveness remains uncertain.

MATERIALS AND METHODS

A decision-analytic (Markov) model was constructed to estimate life expectancy and lifetime costs for otherwise healthy 64-year-old patients with small (≤ 4 cm) incidentally detected, indeterminate renal lesions on routine imaging (e.g., ultrasound or single-phase CT). Three strategies for evaluating renal lesions for enhancement were compared: multiphase SECT (e.g., true unenhanced and nephrographic phase), multiphasic MRI, and single-phase DECT (nephrographic phase in dual-energy mode). The model incorporated modality-specific diagnostic test performance, incidence, and prevalence of incidental renal cell carcinomas (RCCs), effectiveness, costs, and health outcomes. An incremental cost-effectiveness analysis was performed to identify strategy preference at willingness-to-pay (WTP) thresholds of $50,000 and $100,000 per quality-adjusted life-year (QALY) gained. Deterministic and probabilistic sensitivity analysis were performed.

RESULTS

In the base case analysis, expected mean costs per patient undergoing characterization of incidental renal lesions were $2567 for single-phase DECT, $3290 for multiphasic CT, and $3751 for multiphasic MRI. Associated quality-adjusted life-years were the highest for single-phase DECT at 0.962, for multiphasic MRI it was 0.940, and was the lowest for multiphasic CT at 0.925. Because of lower associated costs and higher effectiveness, the single-phase DECT strategy dominated the other two strategies.

CONCLUSIONS

Single-phase DECT is potentially more cost-effective than multiphasic SECT and MRI for evaluating small incidentally detected indeterminate renal lesions.

Teenager with a Primary Renal Lymphoma: A Case Report

We report a case of an 18-year-old male patient who was diagnosed with primary renal lymphoma (PRL) through biopsy findings and imaging studies. The patient presented with clinical manifestations of distal renal tubular acidosis including polyuria, polydipsia, lower limb weakness, involuntary weight loss, asthenia and dyspnea. No personal background or relevant medical history was reported. A kidney biopsy showed high grade immature B-cell lymphoproliferative process (Non-Hodgkin's Lymphoma) with a Ki67 value greater than 90%. Complementary studies excluded primary lymphoid migration sites, which confirmed the diagnosis of PRL. The oncology unit initiated treatment with a combination of medications due to lack of protocols for the specific treatment. Besides the fact that this condition is rare, it also shows a unique symptoms presentation and non-typical findings in imaging methods. Also, it is important to underline the fact that the treatment is not yet specified for such type of cancer and different combinations are needed to control the disease.

Renal Mass Biopsy is Associated with Reduction in Surgery for Early-Stage Kidney Cancer

OBJECTIVE

To determine whether use of renal mass biopsy may be associated with a reduction in surgery for patients with small, localized renal cell carcinoma (cT1aN0M0), especially among older patients and patients with greater comorbidity burden.

METHODS

A total of 106,258 patients with cT1aN0M0 renal cell carcinoma from 2004 to 2015 were analyzed in the National Cancer Data Base. Multivariable logistic regression identified independent associations with nonsurgical management, receipt of biopsy, and pathologic upstaging. Marginal effects were derived by age and comorbidity. A sensitivity analysis was conducted in years identifying patients undergoing active surveillance (2010-2015).

RESULTS

There was increased use of biopsy (8.0%-15.3%) and nonsurgical management (11.7%-15.6%) over time. Biopsy was significantly associated with use of nonsurgical management (OR 4.80 [95%CI 4.58-5.02], P <.001) as well as active surveillance (OR 1.87 [1.69-2.07], P <.001) in the sensitivity analysis. Individual predicted probability of undergoing nonsurgical management ranged from 3% to 92% (median 31.4% with use of biopsy) and increased with age and comorbidity. Pathologic tumor upstaging (≥pT3a) occurred more frequently for patients receiving biopsy compared to no biopsy (5.8% vs 3.3%, P <.001). After adjustment, biopsy remained a statistically significant predictor of upstaging (OR 1.31 [95%CI 1.24-1.38], P <.001).

CONCLUSION

Overall, biopsy demonstrated a strong, independent association with reduced use of surgery for cT1aN0M0 kidney cancer, especially with increasing age and comorbidity. The potential association of renal mass biopsy with upstaging warrants caution, but it is uncertain whether it impacts prognosis relative to true perinephric fat invasion.

Renal mass biopsy: an oncological conundrum

PURPOSE OF REVIEW

We evaluate the reasons that the majority of urologists infrequently biopsy a T1a small renal mass (SRM).

RECENT FINDINGS

The majority of urologists report that a renal mass biopsy will not change their management in patients with a SRM given concerns of safety and efficacy of the biopsy. However, when comparing the safety and efficacy of SRM biopsy with neoplasms in all other major organ systems (all of which require biopsy prior to treatment), renal mass biopsy results are favorable. In addition to being safe and effective, renal mass biopsy should be more cost-effective for the healthcare system. Finally, in properly selected patients, renal mass biopsy can be performed in the urologist's office, thereby further decreasing cost.

SUMMARY

Renal mass biopsy is an essential clinical tool that needs to be incorporated into the decision-making process among patients with a T1a SRM. A biopsy-driven, tissue-specific diagnosis of SRMes should become the standard of care in urology to bring us to parity with standard practice to management of lesions identified in every other organ system.

Active Surveillance Versus Nephron-Sparing Surgery for a Bosniak IIF or III Renal Cyst: A Cost-Effectiveness Analysis

OBJECTIVE

The objective of our study was to evaluate the cost-effectiveness of active surveillance (AS) versus nephron-sparing surgery (NSS) in patients with a Bosniak IIF or III renal cyst.

MATERIALS AND METHODS

Markov models were developed to estimate life expectancy and lifetime costs for 60-year-old patients with a Bosniak IIF or III renal cyst (the reference cases) managed by AS versus NSS. The models incorporated the malignancy rates, reclassification rates during follow-up, treatment effectiveness, complications and costs, and short- and long-term outcomes. An incremental cost-effectiveness analysis was performed to identify management preference under an assumed $75,000 per quality-adjusted life-year (QALY) societal willingness-to-pay threshold, using data from studies in the literature and the 2015 Medicare Physician Fee Schedule. The effects of key parameters were addressed in a multiway sensitivity analysis.

RESULTS

The prevalence of malignancy for Bosniak IIF and III renal cysts was 26% (25/96) and 52% (542/1046). Under base case assumptions for Bosniak IIF cysts, the incremental cost-effectiveness ratio of NSS relative to AS was $731,309 per QALY for women, exceeding the assumed societal willingness-to-pay threshold, and AS outperformed NSS for both life expectancy and cost for men. For Bosniak III cysts, AS yielded greater life expectancy (24.8 and 19.4 more days) and lower lifetime costs (cost difference of $12,128 and $11,901) than NSS for men and women, indicating dominance of AS over NSS. Superiority of AS held true in sensitivity analyses for men 46 years old or older and women 57 years old or older even when all parameters were set to favor NSS.

CONCLUSION

AS is more cost-effective than NSS for patients with a Bosniak IIF or III renal cyst.

CT and MRI of small renal masses

Small renal masses are increasingly detected incidentally at imaging. They vary widely in histology and aggressiveness, and include benign renal tumors and renal cell carcinomas that can be either indolent or aggressive. Imaging plays a key role in the characterization of these small renal masses. While a confident diagnosis can be made in many cases, some renal masses are indeterminate at imaging and can present as diagnostic dilemmas for both the radiologists and the referring clinicians. This article will summarize the current evidence of imaging features that correlate with the biology of small solid renal masses, and discuss key approaches in imaging characterization of these masses using CT and MRI.

Cost and cost-effectiveness studies in urologic oncology using large administrative databases

OBJECTIVE

Urologic cancers are not only among the most common types of cancers, but also among the most expensive cancers to treat in the United States. This study aimed to review the use of CEAs and other cost analyses in urologic oncology using large databases to better understand the value of management strategies of these cancers.

METHODS

A literature review on CEAs and other cost analyses in urologic oncology using large databases.

RESULTS

The options for and costs of diagnosing, treating, and following patients with urologic cancers can be expected to rise in the coming years. There are numerous opportunities in each urologic cancer to use CEAs to both lower costs and provide high-quality services. Improved cancer care must balance the integration of novelty with ensuring reasonable costs to patients and the health care system.

CONCLUSION

With the increasing focus cost containment, appreciating the value of competing strategies in caring for our patients is pivotal. Leveraging methods such as CEAs and harnessing large databases may help evaluate the merit of established or emerging strategies.

Image-guided biopsy of small (≤4 cm) renal masses: the effect of size and anatomical location on biopsy success rate and complications

OBJECTIVE

To study the influence of tumour diameter and anatomy on the success and complication rates of small renal mass (SRM, ≤4 cm) core biopsy.

METHODS

Retrospective analysis of SRMs that underwent ultrasound or CT-guided biopsy. Diagnostic and complication rates were compared according to tumour size (subcategorised as axial diameter ≤2 cm, >2 to- ≤3 cm, >3-≤4 cm) and anatomical disposition (exophytic/endophytic, centrality, polar location and anterior/posterior).

RESULTS

94 patients (54 male; age range 21.8-84.3 years) with 95 SRMs underwent biopsy. The first biopsy was diagnostic in 81/95 (85.3%). Seven patients underwent repeat biopsy (6/7 diagnostic), to give an overall diagnostic rate of 91.5%. The primary diagnostic rates in the ≤2, >2-≤3 , >3-≤4 cm groups were 21/25 (84%); 38/44 (86.4%) and 22/26 (84.6%) respectively and were similar (p = 1.00). Anterior and upper pole SRMs were more likely to fail initial biopsy (odds ratio 13.8, p < 0.01; and odds ratio 4.35, p = 0.04) respectively, but other anatomical factors were not relevant. Complications occurred in 14% (all conservatively managed perinephric haematomas; Clavien-Dindo Grade 1) and size or location were not relevant.

CONCLUSION

Image-guided biopsy of SRMs has a high diagnostic rate irrespective of tumour size. Anterior and upper pole location had lower diagnostic rates. Biopsy should be considered for all patients with SRMs, if the result will impact on management and we list specific scenarios where an SRM biopsy may be helpful. Advances in knowledge: SRM size does not affect the likelihood of a diagnostic biopsy.

Evaluation and management of a large incidentally discovered renal mass

Increasingly, renal cell cancer is diagnosed because of an incidental finding of a renal mass on an imaging study. Incidentally discovered masses are more likely to be small and, if malignant, represent localized renal cell cancer. The imaging features of the tumor and patient characteristics inform the management options, which favor a nephron-sparing approach over radical nephrectomy. Clinical stage at the time of diagnosis has important prognostic implications for the patient. This article reviews the presentation, diagnostic evaluation, and management of an incidentally discovered renal mass.

Diagnostic accuracy of contrast-enhanced ultrasound for characterization of kidney lesions in patients with and without chronic kidney disease

BACKGROUND

Patients with chronic kidney disease are at increased risk of cystic kidney disease that requires imaging monitoring in many cases. However, these same patients often have contraindications to contrast-enhanced computed tomography and magnetic resonance imaging. This study evaluates the accuracy of contrast-enhanced ultrasound (CEUS), which is safe for patients with chronic kidney disease, for the characterization of kidney lesions in patients with and without chronic kidney disease.

METHODS

We performed CEUS on 44 patients, both with and without chronic kidney disease, with indeterminate or suspicious kidney lesions (both cystic and solid). Two masked radiologists categorized lesions using CEUS images according to contrast-enhanced ultrasound adapted criteria. CEUS designation was compared to histology or follow-up imaging in cases without available tissue in all patients and the subset with chronic kidney disease to determine sensitivity, specificity and overall accuracy.

RESULTS

Across all patients, CEUS had a sensitivity of 96% (95% CI: 84%, 99%) and specificity of 50% (95% CI: 32%, 68%) for detecting malignancy. Among patients with chronic kidney disease, CEUS sensitivity was 90% (95% CI: 56%, 98%), and specificity was 55% (95% CI: 36%, 73%).

CONCLUSIONS

CEUS has high sensitivity for identifying malignancy of kidney lesions. However, because specificity is low, modifications to the classification scheme for contrast-enhanced ultrasound could be considered as a way to improve contrast-enhanced ultrasound specificity and thus overall performance. Due to its sensitivity, among patients with chronic kidney disease or other contrast contraindications, CEUS has potential as an imaging test to rule out malignancy.

TRIAL REGISTRATION

This trial was registered in clinicaltrials.gov, NCT01751529 .

Aorta-Lesion-Attenuation-Difference (ALAD) on contrast-enhanced CT: a potential imaging biomarker for differentiating malignant from benign oncocytic neoplasms

OBJECTIVE

To evaluate whether the Aorta-Lesion-Attenuation-Difference on contrast-enhanced CT can aid in the differentiation of malignant and benign oncocytic renal neoplasms.

MATERIALS AND METHODS

Two independent cohorts-an initial (biopsy) dataset and a validation (surgical) dataset-with oncocytomas and chromophobe renal cell carcinomas (chRCC) were included in this IRB-approved retrospective study. A region of interest was placed on the renal mass and abdominal aorta on the same CT image slice to calculate an Aorta-Lesion-Attenuation-Difference (ALAD). ROC curves were plotted for different enhancement phases, and diagnostic performance of ALAD for differentiating chRCC from oncocytomas was calculated.

RESULTS

Seventy-nine renal masses (56 oncocytomas, 23 chRCC) were analyzed in the initial (biopsy) dataset. Thirty-six renal masses (16 oncocytomas, 20 chRCC) were reviewed in the validation (surgical) cohort. ALAD showed a statistically significant difference between oncocytomas and chromophobes during the nephrographic phase (p < 0.001), early excretory phase (p < 0.001), and excretory phase (p = 0.029). The area under the ROC curve for the nephrographic phase was 1.00 (95% CI: 1.00-1.00) for the biopsy dataset and showed the narrowest confidence interval. At a threshold value of 25.5 HU, sensitivity was 100 (82.2%-100%) and specificity was 81.5 (61.9%-93.7%). When tested on the validation dataset on measurements made by an independent reader, the AUROC was 0.93 (95% CI: 0.84-1.00) with a sensitivity of 100 (80.0%-100%) and a specificity of 87.5 (60.4%-97.8%).

CONCLUSIONS

Nephrographic phase ALAD has potential to differentiate benign and malignant oncocytic renal neoplasms on contrast-enhanced CT if histologic evaluation on biopsy is indeterminate.

Smears are important for adequate cytologic diagnosis of kidney lesions

INTRODUCTION

Traditionally at our institution, smears with or without liquid-based cytology (LBC) and core biopsies (CBs) have been obtained by radiologists performing image-guided fine-needle aspiration biopsies (FNABs) of deep organs. Since 2015, however, there has been a shift to providing cytology with samples for LBC only when obtaining CBs. The impression among our institution's cytologists is that LBC alone is less often adequate for diagnosis compared with smears and LBC together. We examined a series of kidney FNABs pre- and post-"LBC only" to evaluate this impression.

MATERIALS AND METHODS

With institutional review board approval, we compared all kidney FNABs from 2012 to those from 2015. We recorded the type(s) of cytology preparation(s), the number of cytology slides, the cytology diagnosis, the concurrent CB diagnosis, and whether there was a subsequent excision and the excision diagnosis. We examined cytology and CB slides as needed.

RESULTS

In 2012, 105 patients underwent 111 kidney biopsies, 109 with smears made. In 2015, 58 patients underwent 62 kidney biopsies, 7 with smears made. In 2012, there were 13 (12%) nondiagnostic (ND) cytology cases and 19 (17%) cases where the cytology and CB diagnoses were discrepant. By comparison, in 2015, there were 20 (32%) ND cytology cases and 21 (33%) discrepant cases.

CONCLUSIONS

There were more cytology slides per case and fewer ND diagnoses in 2012 compared with 2015 (12% versus 32%, respectively, P = 0.001). Concordance was also better in 2012 (83% versus 67%, P = 0.015). We believe that our metrics would improve if we returned to the procedures followed in 2012.

Material Separation Using Dual-Energy CT: Current and Emerging Applications

Dual-energy (DE) computed tomography (CT) offers the opportunity to generate material-specific images on the basis of the atomic number Z and the unique mass attenuation coefficient of a particular material at different x-ray energies. Material-specific images provide qualitative and quantitative information about tissue composition and contrast media distribution. The most significant contribution of DE CT-based material characterization comes from the capability to assess iodine distribution through the creation of an image that exclusively shows iodine. These iodine-specific images increase tissue contrast and amplify subtle differences in attenuation between normal and abnormal tissues, improving lesion detection and characterization in the abdomen. In addition, DE CT enables computational removal of iodine influence from a CT image, generating virtual noncontrast images. Several additional materials, including calcium, fat, and uric acid, can be separated, permitting imaging assessment of metabolic imbalances, elemental deficiencies, and abnormal deposition of materials within tissues. The ability to obtain material-specific images from a single, contrast-enhanced CT acquisition can complement the anatomic knowledge with functional information, and may be used to reduce the radiation dose by decreasing the number of phases in a multiphasic CT examination. DE CT also enables generation of energy-specific and virtual monochromatic images. Clinical applications of DE CT leverage both material-specific images and virtual monochromatic images to expand the current role of CT and overcome several limitations of single-energy CT. (©)RSNA, 2016.

The spectrum of renal cell carcinoma in adults

The spectrum of renal cell carcinoma (RCC) includes many neoplasms with distinct cytogenetics, biologic behaviors, and imaging appearances. The advent of molecular therapies targeting different tumor types, new insights into the relative roles of biopsy and surveillance for small incidental tumors, and a growing array of nephron-sparing interventions have altered management of RCC. Similarly, the role of the radiologist is changing, and it is becoming increasingly important for radiologists to familiarize themselves with the various types of RCC. This article introduces the reader to the common and uncommon recognized types of renal cell carcinoma and discusses how these neoplasms differ in imaging appearance and behavior.

Cost Comparisons Between Different Techniques of Percutaneous Renal Biopsy for Small Renal Masses

PURPOSE

To compare the costs associated with ultrasound (US)-guided hospital-based (UGHB), CT-guided hospital-based (CTG), and US-guided office-based (UGOB) percutaneous renal biopsy (PRB) for small renal masses (SRMs).

METHODS

We retrospectively analyzed patient demographics, tumor characteristics, R.E.N.A.L. nephrometry scores, and cost data of patients undergoing PRB for SRM at our institution from May 2012 to September 2015. Cost data, including facility costs, professional fees, and pathology, were obtained from the departments of urology, radiology, and pathology.

RESULTS

A total of 78 patients were included in our analysis: 19, 31, and 28 UGHB, CTG, and UGOB, respectively. There was no difference in age, gender distribution, or tumor size among the three groups (p-values 0.131, 0.241, and 0.603, respectively). UGOB tumors had lower R.E.N.A.L. nephrometry scores (p=0.008). There were no differences in nondiagnostic rates between the UGHB, CTG, and UGOB groups [4 (21%), 5 (16%), and 6 (21%)] (p=0.852). There were no differences in final tumor treatment strategies utilized among the UGHB, CTG, and UGOB groups (p=0.447). There were 0, 2 (6%), and 0 complications in the UGHB, CTG, and UGOB biopsy groups. Total facility costs were $3449, $3280, and $1056 for UGHB, CTG, and UGOB PRB, respectively (p<0.0001). There was no difference between the urologist's and radiologist's professional fees (p=0.066). Total costs, including facility costs, pathology fees, and professional fees, were $4598, $4470, and $2129 for UGHB, CTG, and UGOB renal biopsy, respectively (p<0.0001).

CONCLUSION

For select patients with less anatomically complex, exophytic, and posteriorly located tumors, UGOB PRB provides equivalent diagnostic and complication rates while being significantly more cost-effective than either UGHB or CTG renal biopsy.

ACR Appropriateness Criteria indeterminate renal mass

Renal masses are increasingly detected in asymptomatic individuals as incidental findings. An indeterminate renal mass is one that cannot be diagnosed confidently as benign or malignant at the time it is discovered. CT, ultrasonography, and MRI of renal masses with fast-scan techniques and intravenous (IV) contrast are the mainstays of evaluation. Dual-energy CT, contrast-enhanced ultrasonography, PET/CT, and percutaneous biopsy are all technologies that are gaining traction in the characterization of the indeterminate renal mass. In cases in which IV contrast cannot be used, whether because of IV contrast allergy or renal insufficiency, renal mass classification with CT is markedly limited. In the absence of IV contrast, ultrasonography, MRI, and biopsy have some advantages. Owing to the low malignant and metastatic potential of small renal cell carcinomas (≤4 cm in diameter), active surveillance is additionally emerging as a diagnostic strategy for patients who have high surgical risk or limited life expectancy. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 3 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and application by the panel of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Percutaneous biopsy for risk stratification of renal masses

The increased use of abdominal imaging has led to identification of more patients with incidental renal masses, and renal mass biopsy (RMB) has become a popular method to evaluate unknown renal masses prior to definitive treatment. Pathologic data obtained from biopsy may be used to guide decisions for treatment and may include the presence or absence of malignant tumor, renal cell cancer subtype, tumor grade and the presence of other aggressive pathologic features. However, prior to using RMB for risk stratification, it is important to understand whether RMB findings are equivalent to pathologic analysis of surgical specimens and to identify any potential limitations of this approach. This review outlines the advantages and limitations of the current studies that evaluate RMB as a guide for treatment decision in patients with unknown renal masses. In multiple series, RMB has demonstrated low morbidity and a theoretical reduction in cost, if patients with benign tumors are identified from biopsy and can avoid subsequent treatment. However, when considering the routine use of RMB for risk stratification, it is important to note that biopsy may underestimate risk in some patients by undergrading, understaging or failing to identify aggressive tumor features. Future studies should focus on developing treatment algorithms that integrate RMB to identify the optimal use in risk stratification of patients with unknown renal masses.

Radiation exposure from CT-guided ablation of renal masses: effects on life expectancy

OBJECTIVE. The purpose of this article is to project the effects of radiation exposure on life expectancy (LE) in patients who opt for CT-guided radiofrequency ablation (RFA) instead of surgery for renal cell carcinoma (RCC). MATERIALS AND METHODS. We developed a decision-analytic Markov model to compare LE losses attributable to radiation exposure in hypothetical 65-year-old patients who undergo CT-guided RFA versus surgery for small (≤ 4 cm) RCC. We incorporated mortality risks from RCC, radiation-induced cancers (for procedural and follow-up CT scans), and all other causes; institutional data informed the RFA procedural effective dose. Radiation-induced cancer risks were generated using an organ-specific approach. Effects of varying model parameters and of dose-reduction strategies were evaluated in sensitivity analysis. RESULTS. Cumulative RFA exposures (up to 305.2 mSv for one session plus surveillance) exceeded those from surgery (up to 87.2 mSv). In 65-year-old men, excess LE loss from radiation-induced cancers, comparing RFA to surgery, was 11.7 days (14.6 days for RFA vs 2.9 days for surgery). Results varied with sex and age; this difference increased to 14.6 days in 65-year-old women and to 21.5 days in 55-year-old men. Dose-reduction strategies that addressed follow-up rather than procedural exposure had a greater impact. In 65-year-old men, this difference decreased to 3.8 days if post-RFA follow-up scans were restricted to a single phase; even elimination of RFA procedural exposure could not achieve equivalent benefits. CONCLUSION. CT-guided RFA remains a safe alternative to surgery, but with decreasing age, the higher burden of radiation exposure merits explicit consideration. Dose-reduction strategies that target follow-up rather than procedural exposure will have a greater impact.

Renal Tumor Biopsy for Small Renal Masses: A Single-center 13-year Experience

BACKGROUND

Renal tumor biopsy (RTB) for the characterization of small renal masses (SRMs) has not been widely adopted despite reported safety and accuracy. Without pretreatment biopsy, patients with benign tumors are frequently overtreated.

OBJECTIVE

To assess the diagnostic rate of RTBs, to determine their concordance with surgical pathology, and to assess their impact on management.

DESIGN, SETTING, AND PARTICIPANTS

This is a single-institution retrospective study of 529 patients with biopsied solid SRMs ≤4 cm in diameter. RTBs were performed to aid in clinical management.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Diagnostic and concordance rates were presented using proportions. Factors that contributed to a diagnostic biopsy were identified using a multivariable logistic regression.

RESULTS AND LIMITATIONS

The first biopsy was diagnostic in 90% (n=476) of cases. Of the nondiagnostic biopsies, 24 patients underwent a second biopsy of which 83% were diagnostic. When both were combined, RTBs yielded an overall diagnostic rate of 94%. Following RTB, treatment could have been avoided in at least 26% of cases because the lesion was benign. Tumor size and exophytic location were significantly associated with biopsy outcome. RTB histology and nuclear grade were highly concordant with final pathology (93% and 94%, respectively). Adverse events were low (8.5%) and were all self-limited with the exception of one. Although excellent concordance between RTB and final pathology was observed, only a subset of patients underwent surgery following biopsy. Thus it is possible that some patients were misdiagnosed.

CONCLUSIONS

RTB of SRMs provided a high rate of diagnostic accuracy, and more than a quarter were benign. Routine RTB for SRMs informs treatment decisions and diminishes unnecessary intervention. Our results support its systematic use and suggest that a change in clinical paradigm should be considered.

PATIENT SUMMARY

Renal tumor biopsy (RTB) for pretreatment identification of the pathology of small renal masses (SRMs) is safe and reliable and decreases unnecessary treatment. Routine RTB should be considered in all patients with an indeterminate SRM for which treatment is being considered.

The impact of the Patient Protection and Affordable Care Act on radiology: beyond reimbursement

The 2014 ACR Forum focused on the noneconomic implications of the Affordable Care Act on the field of radiology, with specific attention to the importance of the patient experience, the role of radiology in public and population health, and radiology's role in the effort to lower overall health care costs. The recommendations generated from the Forum seek to inform ACR leadership on the best strategies to pursue to best prepare the radiology community for the rapidly evolving health care landscape.

Patient and tumor characteristics can predict nondiagnostic renal mass biopsy findings

PURPOSE

Identification of patient and tumor characteristics associated with nondiagnostic biopsies is necessary to improve prebiopsy counseling and patient selection.

MATERIALS AND METHODS

We reviewed the clinical records and prebiopsy imaging of all patients treated with percutaneous biopsy for a renal mass 7 cm or less. Univariate and multivariate logistic regression models were constructed to examine the association between biopsy outcome and clinical/radiographic features.

RESULTS

A total of 565 biopsies of renal tumors 7 cm or less in 525 patients were included in the study. There was no significant difference in age, body mass index, Charlson comorbidity score or gender between the patient cohorts with diagnostic and nondiagnostic biopsy. In 83 of 565 patients (14.7%) overall and in 72 of the 413 (17.4%) with a mass of 4 cm or less the biopsy findings were nondiagnostic. Overall 14.7% of masses were cystic and 85.3% were solid with a median tumor size of 2.75 cm (IQR 2.05-4.25). Independent predictors of nondiagnostic biopsy included cystic features, enhancement less than 20 HU, left tumor, tumor diameter and skin-to-tumor distance. The nondiagnostic rate of repeat biopsies was 20.8%, which did not statistically differ from the nondiagnostic rate at the initial renal mass biopsy attempt. Radiologist or pathologist experience was not associated with the biopsy nondiagnostic rate. In 7 of 565 patients (1.2%) hospital admission was required for adverse events after biopsy.

CONCLUSIONS

Nondiagnostic renal mass biopsies are more common in cystic, nonenhancing, small masses when patients have a skin-to-tumor distance of 13 cm or greater. Excluding patients with these criteria decreased the nondiagnostic rate from 14.7% to 8.7%.