Characterization Of Small Renal Masses Research Articles

The Role of CT Imaging in Characterization of Small Renal Masses.

Small renal masses (SRM) are increasingly detected incidentally during 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 review focuses on CT characterization of small renal masses, perhaps helping us understand small renal masses. The following aspects were considered for the review: (a) assessing the presence of fat, (b) assessing the enhancement, (c) differentiating renal tumor subtype, and (d) identifying valuable CT signs.

Radiomics to better characterize small renal masses.

Radiomics is a specific field of medical research that uses programmable recognition tools to extract objective information from standard images to combine with clinical data, with the aim of improving diagnostic, prognostic, and predictive accuracy beyond standard visual interpretation. We performed a narrative review of radiomic applications that may support improved characterization of small renal masses (SRM). The main focus of the review was to identify and discuss methods which may accurately differentiate benign from malignant renal masses, specifically between renal cell carcinoma (RCC) subtypes and from angiomyolipoma without visible fat (fat-poor AML) and oncocytoma. Furthermore, prediction of grade, sarcomatoid features, and gene mutations would be of importance in terms of potential clinical utility in prognostic stratification and selecting personalised patient management strategies. A detailed search of original articles was performed using the PubMed-MEDLINE database until 20 September 2020 to identify the English literature relevant to radiomics applications in renal tumour assessment. In total, 42 articles were included in the analysis in 3 main categories related to SRM: prediction of benign versus malignant SRM, subtypes, and nuclear grade, and other features of aggressiveness. Overall, studies reported the superiority of radiomics over expert radiological assessment, but were mainly of retrospective design and therefore of low-quality evidence. However, it is clear that radiomics is an attractive modality that has the potential to improve the non-invasive diagnostic accuracy of SRM imaging and prediction of its natural behaviour. Further prospective validation studies of radiomics are needed to augment management algorithms of SRM.

675 - Contrast-enhanced ultrasonography (CEUS) and time/intensity curves for the characterization of small renal masses

675 - Contrast-enhanced ultrasonography (CEUS) and time/intensity curves for the characterization of small renal masses

Urinary aquaporin1 and perilipin2: Can these novel markers accurately characterize small renal masses and help guide patient management?

To evaluate the role of urine aquaporin1 and perilipin2 as biomarkers adjunct to renal mass biopsy in guiding the management of patients with small renal masses. Preoperative aquaporin1 and perilipin2 levels in 57 patients with small renal masses undergoing partial nephrectomy were analyzed and compared with postoperative tumor histology. An algorithm was created utilizing aquaporin1 and perilipin2 in conjunction with renal mass biopsy. Cut-off values were implemented to maximize biomarker sensitivity and specificity. Renal mass biopsy utilization and intervention were then compared with rates in traditional renal mass biopsy algorithms. All clear cell and papillary renal cell carcinomas were correctly identified and assigned to the treatment path. All benign lesions were correctly sorted to a confirmatory renal mass biopsy path. Two chromophobe masses did not have elevated aquaporin1 and perilipin2, and would require renal mass biopsy. Compared with protocols that call for all small renal masses to be biopsied, confirmatory renal mass biopsy could have been safely avoided in 74% of patients with elevated aquaporin1 and perilipin2. Compared with protocols that do not utilize renal mass biopsy, surgical intervention would have been avoided in 23% of patients with benign masses. Aquaporin1 and perilipin2 possess high sensitivity and specificity for detecting clear cell and papillary renal cell carcinoma. Use of these markers might compliment renal mass biopsy in the characterization of small renal masses.

Epidemiology and diagnostic assessment of small renal masses

The incidence of small renal masses has been rising over the last few decades. At the same time, mortality of renal cell carcinoma (RCC) is decreasing. These trends can be explained by the availability of improved therapeutic measures and the good prognosis of small renal masses (SRM) turning out to be histopathologically benign or of low malignancy in many cases. The aim of this article is to present epidemiology and diagnostic assessment of SRM. Statistics, basic research, guidelines. The incidence of SRM is rising due to the widespread use of imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and contrast-enhanced ultrasound (CEUS). Sensitivity is excellent for CEUS and for CECT in the characterization of SRM, while good specificity values can be reached by MRI. For characterization of complex cystic renal masses, CEUS has good diagnostic accuracy. Due to improved diagnostic possibilities, SRMs can be diagnosed in early asymptomatic stages. As SRM have agood prognosis and often are of low malignancy therapy, options should be carefully considered; especially in older patients, active surveillance should considered.

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

BackgroundRenal 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. ObjectiveTo assess the diagnostic rate of RTBs, to determine their concordance with surgical pathology, and to assess their impact on management. Design, setting, and participantsThis is a single-institution retrospective study of 529 patients with biopsied solid SRMs ≤4cm in diameter. RTBs were performed to aid in clinical management. Outcome measurements and statistical analysisDiagnostic and concordance rates were presented using proportions. Factors that contributed to a diagnostic biopsy were identified using a multivariable logistic regression. Results and limitationsThe 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. ConclusionsRTB 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 summaryRenal 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.

MR imaging in the characterization of small renal masses

The aim of our study was to evaluate the effectiveness of MR imaging for the characterization of small (<2 cm) renal lesions described as indeterminate on prior US or CT. Sixty-three small renal masses in 51 patients considered indeterminate on prior ultrasound or CT scans were included in the study. A retrospective evaluation of the examinations was performed independently by two body magnetic resonance imaging (MRI) radiologists who were unaware of the final diagnosis. A 3-point confidence scale (1: benign, 2: indeterminate, and 3: malignant) was established to determine the level of suspicion for malignancy. Interobserver agreement was determined with a weighted kappa statistic. The diagnosis was verified by imaging follow-up of at least 24 months (mean 60 months) in 53 lesions and by pathology in 10 lesions. MRI detected all eight malignancies in the series. There were eight malignant lesions and two benign lesions among those with pathologic follow-up. No interval growth or evidence of malignancy in the remaining 53 lesions was found for a minimum of 24 months by repeat imaging. The sensitivity, specificity, positive predictive value, and negative predictive value of MRI for differentiating benign from malignant small renal lesions were 100% (62.9-100%, 95% CI), 94.5% (84.9-98.8%, 95% CI), 72.7% (39.1-93.6%, 95% CI), and 100% (93.1-100%, 95% CI), respectively. The kappa value for interobserver agreement was 0.77 (95% CI 0.59-0.96, p-value <0.001). MR imaging is an effective method for characterizing small (<2 cm) renal masses found to be indeterminate by US or CT.

Characterization of Small Renal Masses Less than 4 cm with Quadriphasic Multidetector Helical Computed Tomography: Differentiation of Benign and Malignant Lesions

PurposeTo identify the characteristic quadriphasic (unenhanced, corticomedullary, nephrographic, and excretory phase) helical multidetector computed tomography (MDCT) features of renal masses less than 4 cm to distinguish benign from malignant renal masses.Materials and MethodsIn total, 84 patients were retrospectively analyzed to determine the characteristic features for the prediction of subtypes of small renal masses. The patients' age, gender, and tumor size and CT features, including the presence of intra-tumor degenerative changes, septation, calcification, and wall irregularity, were evaluated. In addition, the degree and pattern of enhancement obtained during four phases were analyzed. The relationship between the subtype of the small renal masses and the gender, morphological features, and pattern of contrast enhancement on the CT was analyzed by using the chi-square test. Tumor size and degree of contrast enhancement were compared by the Mann-Whitney U test. The predictive value of each of the CT features was determined by multivariate logistic regression analysis.ResultsOf the 84 small renal masses, 17 (20%) were benign and 67 (80%) were malignant. Univariate analysis revealed that renal cell carcinoma lesions showed heterogeneous enhancement (p=0.002) and higher mean attenuation value on the corticomedullary and nephrographic phases (135.1±53.9, p=0.000, and 132.4±43.6, p=0.006). The multivariate analysis with logistic regression model showed that only the mean attenuation value on the corticomedullary phase had a statistically significant correlation (p=0.021).ConclusionsFor the characterization of small renal masses, the degree of enhancement on the corticomedullary phase is a valuable parameter. Furthermore, the heterogeneous enhancement pattern and degree of enhancement on the nephrographic phase can provide information for differentiating small renal masses.

MR Imaging of papillary renal neoplasms: potential application for characterization of small renal masses

The purpose of our study was to evaluate the role of MRI in demonstrating the precise nature of papillary renal tumors (P RCC) and its potential application to select patients for partial surgery. Ninety-seven tumors less than or equal to 3 cm in size [55 papillary renal cell carcinoma - 42 clear cell renal carcinoma (CC RCC)] were preoperatively evaluated by MRI. Imaging findings were assessed with a special focus on the aspect of the tumoral process. Correlations were performed with pathologic staging after surgery. At pathology, 92 tumors were established to be staged p T1 and 5 were p T3 ( 3 cases of CC RCC and 2 cases of P RCC). Ninety-four percent of papillary tumors exhibited low signal intensity with homogeneous pattern on T2-weighted images. All clear cell carcinoma were hyperintense and heterogeneous on T2-weighted sequence. Enhancement was lower and delayed in the papillary type in comparison with the clear cell type. MRI is accurate enough to predict the 'histologic' nature of papillary renal carcinoma. It is an additional argument to propose that the tumor can be removed by partial surgery.

Evaluation of small (

Our purpose was to determine whether thin overlapping reconstructions using MDCT improve the detection and characterization of small renal masses. Thirty-seven patients were scanned with MDCT using 2.5-mm collimation. Nephrographic phase data were reconstructed in two ways: a standard protocol (5-mm section thickness, no overlap) and an experimental protocol (3-mm section thickness, 50% overlap). Masses were detected and classified into three groups: group 1, measuring less than 20 H on both protocols (classified as cysts on both); group 2, measuring 20 H or greater on standard protocol and less than 20 H on experimental protocol (classified as cysts using experimental protocol only); and group 3, measuring 20 H or greater on both protocols (not classified as cysts using either protocol). Masses 10 mm or larger in group 3 were evaluated further for enhancement. Statistically significant differences between protocols were assessed using an analysis of counts and proportions. Of 175 detected lesions, 29 (17%) were detected only with the experimental protocol; all but one were smaller than 5 mm. Using the experimental protocol, of 45 masses between 5 and 10 mm, the number of masses that could be characterized as cysts increased from 13 (29%) to 38 (84%). The overall number of indeterminate lesions was reduced from 101 (69%) of 146 lesions detected with the standard protocol to 86 (53%) of 161 lesions detected with the experimental protocol. Using MDCT and thin overlapping reconstructions, renal cysts as small as 5 mm can be diagnosed with more confidence than is possible with standard reconstructions, and the overall number of indeterminate renal masses is reduced.

Multiphasic helical CT of the kidney: increased conspicuity for detection and characterization of small (< 3-cm) renal masses.

To evaluate the potential of thin-section multiphasic helical computed tomography (CT) in the detection and characterization of small (< 3.0-cm) renal masses. Identically collimated helical CT of the kidney was performed before and after administration of contrast material in 93 patients with small renal masses. Helical CT scans were obtained during the corticomedullary and nephrographic phases. Differences between attenuation of the lesion and that of the kidney were measured quantitatively. The presence of a mass or absence of disease was confirmed with clinical, imaging, and histologic findings. The number of masses smaller than 3.0 cm detected on corticomedullary-phase scans (n = 211) was statistically significantly fewer than those on nephrographic-phase scans (n = 295) (P < .01). Mean differences in enhancement between the renal cortex and masses were 148 HU +/- 54 and 137 HU +/- 44 during the corticomedullary and nephrographic phases, respectively, and the difference in attenuation of the renal medulla and that of the masses was statistically significantly greater during the nephrographic phase (P < .01). False-positive results (n = 9) occurred only on corticomedullary-phase scans because of lack of enhancement of the renal medulla. Nephrographic-phase scans enabled greater lesion detection and better characterization of small renal masses than corticomedullary-phase scans. Nephrographic-phase scans should be obtained when only monophasic scanning is used to detect small renal masses.

Small (

The purpose of this study was to evaluate the ability of in-phase spoiled gradient echo combined with chemically selective fat suppression or out-of-phase spoiled gradient echo MR images to characterize small renal masses as angiomyolipomas. Eleven patients with a total of 35 small (< 1.5 cm) angiomyolipomas underwent MR examination at 1.5T. Eight patients had solitary and three patients had multiple angiomyolipomas. One of the patients with multiple angiomyolipomas had tuberous sclerosis and the number of angiomyolipomas were quantified as 20. MR examinations included in-phase spoiled gradient echo (all patients), chemically selective fat suppressed spin echo (six patients), chemically selective fat suppressed spoiled gradient echo (three patients), selective water excitation spoiled gradient echo (one patient) and out-of-phase spoiled gradient echo (seven patients). Angiomyolipomas were minimally (4 lesions) or moderately (31 lesions) high in signal intensity relative to renal cortex on in-phase spoiled gradient echo images. On out-of-phase spoiled gradient echo images, demonstration of signal void fat-water phase cancellation was present in all eight lesions in the seven patients who were imaged with this sequence. Small lesion size rendered the entire angiomyolipoma signal void in seven of these eight lesions due to phase cancellation artifact. Signal void phase cancellation of lesion border or signal void of the entire angiomyolipoma resulted in high lesion conspicuity in all lesions. Mild loss of signal intensity was observed in 7 lesions and moderate loss of signal intensity noted in 25 lesions on chemically selective fat suppressed images. On chemically selective fat-suppressed images, seven lesions were difficult to identify due to limited signal differences between medium intensity cortex and low intensity angiomyolipomas (six lesions in two patients) and moderate breathing artifact (one lesion in one patient). Characterization of small renal masses as angiomyolipomas may be reliably performed using the combination of in-phase and fat-attenuating MR sequences. Consistent image quality and high conspicuity of fat-water phase cancellation interfaces renders out-of-phase imaging a reliable fat attenuating method to demonstrate the presence of fat in small angiomyolipomas. Breath-hold fat-suppressed spoiled gradient echo is also effective; however, this technique demonstrates less signal loss in fatty lesions and is subject to problems with inhomogeneity of fat suppression.

Problems in the Detection and Characterization of Small Renal Masses

Problems in the Detection and Characterization of Small Renal Masses

Problems in the detection and characterization of small renal masses.

Problems in the detection and characterization of small renal masses.