in consensus reading in 52 groins of 26 patients with this tumor entity. RESULTS: A total ... apparent diffusion coefficient (ADC) maps in differentiating clear cell.
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planar scintigraphies was carried out by a twin head gamma camera (Siemens, ECAM and Symbia S) and indirect body contouring. Additionally, we subsequently performed SPECT/CT of the abdomen und inguinal regions using a twin-head hybrid camera system (Siemens Symbia T and Symbia Intevo). Imaging data of both modalities were prospectively evaluated by two experienced physicians in consensus reading in 52 groins of 26 patients with this tumor entity. RESULTS: A total of 71 SLNs in 37 groins were identified by planar scintigraphy. Non-visualization was observed in 15 (28.8%) inguinal basins using planar scans. 82 SLNs in 42 groins were detected by SPECT/CT (non-visualization in 10 (19.2%) groins). SPECT/CT revealed 8 inguinal hotspots as shown by planar imaging in 7 groins as false positive. 19 inguinal SLNs in 16 groins were missed on planar imaging and could be detected by SPECT/CT only. In contrast to 2D planar scintigraphy, SPECT/CT allowed to determine the precise anatomical localization of the SLNs in all 42 groins. CONCLUSIONS: SPECT/CT is capable of detecting SLNs missed by planar imaging, it reduces the number of false positive findings and shows the morphological location of SLNs more accurately. If available, SPECT/CT should be used for preoperative SLN imaging in penile cancer patients with non-palpable inguinal lymph node status. Source of Funding: None
MP18-11 EXPLORING THE CLINICAL UPTAKE AND USE OF PSMA PET MRI HYBRID IMAGING IN PROSTATE CANCER PATIENTS AT AN ACADEMIC CENTER IN AUSTRALIA Andre Joshi*, Cheryl Nicholson, Handoo Rhee, Ian McKenzie, Janelle Munns, Greg Malone, Eric Chung, Malcolm Lawson, Peter Heathcote, John Preston, Simon Wood, Sonja Gustafson, Ken Miles, Ian Vela, Brisbane, Australia INTRODUCTION AND OBJECTIVES: Positron emission tomography (PET) using prostate specific membrane antigen (PSMA) detects prostate cancer lesions with a higher sensitivity and specificity when compared to standard imaging. Hybrid PET Magnetic Resonance Imaging (MRI) has now been introduced to provide potentially improved characterization of lesions with added PET avidity. We evaluate the utilization of this novel imaging modality at the Princess Alexandra Hospital (PAH) and assess our initial outcomes. METHODS: A retrospective review of all PSMA PET MRI scans undertaken at the PAH since the introduction of the technology was performed. Imaging data was collected alongside baseline clinical data, PSA, previous histology, previous treatments, indication of scans, requesting clinicians and clinical outcomes. RESULTS: A total of 187 PSMA PET MRI scans were performed at the PAH from April 2015 to October 2016. The median age of imaged patients was 68, with a median PSA of 6ng/ml and Gleason score of 7 at the time of scan. 153 scans were positive for PSMA avid disease (81.8%). Scans were requested in the setting of biochemical recurrence (n¼94), preoperative staging (n¼77), evaluation of treatment response (n¼11) and diagnostic purposes (n¼5). Urologists requested PSMA PET MRI most frequently with 111 scans, of which 58.6% requested for preoperative staging. Radiation oncologists requested 69 scans with 75.4% of these in the biochemical recurrence setting. Only 7 scans were requested by medical oncologists. Amongst patients with biochemical recurrence the lowest PSA of a positive scan was 0.02 ng/ml. In this group 43 patients had prior surgery with 19 positive scans (44%). 51 patients were treated with ADT and or EBRT and 46 had positive scans (90.2%). 29 patients had tissue samples to validate PSMA PET MRI. 26 patients (89.7%) had adenocarcinoma on histology correlating with avid lesions on PSMA PET.
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CONCLUSIONS: PSMA PET MRI has had rapid uptake in use since introduction at the PAH. Urologists and radiation oncologists appear to utilize this imaging modality most; Urologists for a preoperative “one stop shop” staging study and radiation oncologists in biochemical recurrence. From this data is also appears that a positive PSMA PET/MRI is highly suggestive of prostate cancer, with a specificity of 89.7%. Hybrid PET/MRI may be used to stage men locally and systemically with one scan, with lower radiation and at PSA 1 ng/ml. This modality has the potential to significantly improve prostate cancer staging and allow early identification of recurrent disease. Source of Funding: None
MP18-12 DIFFUSION WEIGHTED IMAGING: DIFFERENTIATION OF CLEAR CELL FROM PAPILLARY RENAL CELL CARCINOMA S. Mojdeh Mirmomen, Moozhan Nikpanah, Rabindra Gautam, Adam Metwalli, Amir Pourmorteza, William Linehan, Ashkan Malayeri*, Bethesda, MD INTRODUCTION AND OBJECTIVES: Due to the differences in tumor behavior and prognosis, discriminating different subtypes of renal cell carcinoma (RCC) is important. The purpose of this study was to investigate the role of diffusion weighted imaging (DWI) derived apparent diffusion coefficient (ADC) maps in differentiating clear cell renal carcinoma (ccRCC) from papillary subtype (pRCC). METHODS: ADC maps from 97 renal cell carcinoma lesions (20 papillary and 77 clear cell type) from 42 patients were segmented for volumetric and pixel based histogram analysis. Mean, standard deviation, skewness and kurtosis and different quantiles of the histogram were calculated for the segmented lesions. The standard of reference for diagnosis of different types of RCC was histopathology of surgical specimens. Receiver operating characteristic (ROC) analysis was performed for each of the extracted features. RESULTS: Amongst all the above mentioned features, the analysis of the quantiles yielded the highest sensitivity and specificity for differentiation of the two subtypes. The ADC range was between 258 to 3407 and 246 to 3686 mm2/sec for pRCC and ccRCC, respectively. Quantile 30 by ADC threshold of 1500 resulted in 96% sensitivity and 84% specificity that provided the highest sensitivity and specificity among the all features. Area under the curve (AUC) was 0.95. CONCLUSIONS: Volumetric pixel based analysis of the ADC maps is an objective method that can accurately differentiate pRCC from ccRCC.
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Source of Funding: none
MP18-13 TEXTURE ANALYSIS OF ENHANCING, NON-LIPID CONTAINING SOLID RENAL MASSES: DIFFERENTIATION OF MALIGNANT FROM BENIGN RENAL TUMORS. Bino Varghese, Vinay Duddalwar*, Frank Chen, Darryl Hwang, Steven Cen, Bhushan Desai, Gangning Liang, Mihir Desai, Sameer Chopra, Manju Aron, Monish Aron, Inderbir Gill, Los Angeles, CA INTRODUCTION AND OBJECTIVES: Contrast Enhanced Computed Tomography (CECT) is the most common modality of imaging a renal mass. While metrics including pixel enhancement have been described for differentiation of various types of tumors, we describe an additional technique of texture analysis. METHODS: In this Institutional Review Board (IRB) approved, Health Insurance Portability and Accountability Act (HIPAA) compliant, retrospective study, we identified 136 patients with solid, non-lipid containing enhancing renal tumors based on post-surgical pathology examination (94 Malignant, 42 Benign). Here, we test the feasibility using textural biomarkers, to objectively quantify and differentiate the textural heterogeneity of malignant subtypes, here, clear cell renal carcinoma, papillary renal carcinoma, and chromophobe from, benign subtypes, here, oncocytoma and lipid poor angiomyolipoma, using standard-of-care contrast-enhanced computed tomography (CECT) images. RESULTS: Three sets of stepwise logistic regression were used to select the best predictor among all candidate predictors from 2D GLCM, 3D GLCM and spectral (Table 1). The discrimination power gain from spectral metrics in addition to 2D and 3D GLCM combined was assessed using a one-degree freedom chi square test when comparing the area under the curve between the full model and the model without spectral metrics. The full model with 2D, 3D GLCM and spectral predictors yielded an AUC of 0.92 (95% CI: 0.87-0.96), while the model with 2D and 3D only already reached almost the same AUC. The difference between the two model was less than 0.01 (p¼0.89) (Figure 1). CONCLUSIONS: CECT-based texture metrics can differentiate between malignant- and benign-renal tumors, with 2D and 3D GLCM metrics providing the most information for segregating malignant from benign renal tumors. In combination with other metrics such as contrast enhancement, shape metrics etc., texture metrics, have the potential to improve patient management and help stratify renal tumors using prostate CECT.
Source of Funding: This project has received funding from the Whittier Foundation. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Foundation.
MP18-14 MULTIPLE RADIOFREQUENCY ABLATION ZONES ON KIDNEY FUNCTION Julie An*, Shawna Boyle, Venkatesh Krishnasamy, Adam Metwalli, W. Marston Linehan, Bradford Wood, Bethesda, MD INTRODUCTION AND OBJECTIVES: Radiofrequency ablation (RFA) has become an acceptable nephron-sparing treatment for small renal masses. It is sometimes considered for patients with high likelihood of repeat interventions, such as those with multifocal lesions from hereditary syndromes. Available long-term renal functional outcomes for patients with multiple lesions are limited predominantly to the surgical approach, and little is known about the effect of multiple tumor ablations in single procedure. Our aim is to compare the longeterm renal functional changes for patients who had a single lesion vs. of multiple lesions treated with RFA. METHODS: Our institution review board approved study registry was queried for patients treated using RFA with single or multiple ablation zones. This series was limited to first ablative procedures, and follow-up was censored to time of next surgical or interventional procedures. Clinical features and renal functional outcomes as measured by change in eGFR and rate of eGFR
