Four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) MR evaluation of the renal arteries in transplant recipients: Preliminary results.

PURPOSE: To assess the performance of four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) at 3.0T in depicting intrarenal arteries compared with computed tomography angiography (CTA), and its correlation with arterial flowmetry in comparison with Doppler ultrasonography (DUS). MATERIALS AND METHODS: In our prospective single-arm study, subjects were 25 patients who underwent renal transplant-related surgery at our hospital between July 2011 and June 2015. In the morphological study, depictions of renal artery branches delineated by magnetic resonance angiography (MRA)/4D PC-VIPR without gadolinium contrast agent were compared in seven living transplant recipients with the same kidney delineated by CTA in seven living transplant donors. In the flowmetric study, flow velocities in the renal (main stem), segmental, and interlobar arteries during systole and diastole were measured in 12 recipients using noncontrast MRA/4D PC-VIPR, and were compared with those obtained from DUS. RESULTS: Concerning MRA, average confidence levels of delineation rated by six observers for secondary to third level renal artery branches were 82.9-100% and for the fourth to fifth branches were 60.8-89.7% (average kappa value of 0.588 [95% confidence interval: 0.522-0.653]). Total flow velocities measured using 4D PC-VIPR and DUS demonstrated significant correlations during both systole and diastole with acceptable bias (r = 0.902; P < 0.001 in systole and r = 0.734; P < 0.001 in diastole). CONCLUSION: 4D PC-VIPR was useful in generating both morphological and hemodynamic information for evaluation of transplant intrarenal arteries without the need for contrast media. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:595-603.

[Evaluation of CT-Guided Percutaneous Needle Biopsy for Diagnosis of Renal Tumor].

We performed computed tomographic (CT)-guided percutaneous needle biopsy for renal tumors that were difficult to diagnose or were inoperable malignant renal tumors. Nineteen patients who underwent CT-guided percutaneous needle biopsy between November 2007 and March 2015 at Hamamatsu University Hospital were included in this study. The median tumor diameter was 78 mm (40-140 mm). Seventeen patients were diagnosed pathologically by biopsy, but 2 patients could not be diagnosed despite the existence of adequate sample volume. One patient had an adverse complication ; fever (CTCAE ver 4.0 grade 1). The median duration of follow-up was 21 months (0-111 months), no one had tumor seeding along a needle tract. CT-guided percutaneous needle biopsy of renal tumors is helpful for pathological diagnosis and further treatment planning. However, there are still some limitations to obtain an accurate diagnosis.

Feasibility of magnetic resonance elastography for the pancreas at 3T.

PURPOSE: 1) To assess the usefulness of an elastic belt bracing the upper abdomen for reducing the miscalculated areas of the pancreas on 3.0T magnetic resonance elastography (MRE); 2) to test whether MRE can detect difference of stiffness between normal pancreas and the focal pancreatic diseases. MATERIALS AND METHODS: Using an initial eight normal volunteers, miscalculated areas were compared between MRE with the elastic belt and without the belt on 3.0T MRI. Then, using the belt, MRE of the normal pancreas was measured using 14 volunteers and 11 patients with focal pancreatic lesions. RESULTS: The median (95% confidence interval [CI]) percentages of correctly calculated areas were 57.4% (32.9-63.0) with the elastic belt and 35.3% (11.4-60.4) without the belt (P = 0.0078). The stiffness of each pancreatic segment of the normal volunteers (mean ± SE) was 2.37 ± 0.16 kPa for the head, 2.46 ± 0.17 kPa for the body, and 2.58 ± 0.26 kPa for the tail. The stiffness of seven pancreatic cancers was 6.06 ± 0.49 kPa, which was higher than the overall pancreatic stiffness of the normal volunteers (2.47 ± 0.11 kPa, P < 0.0001). Stiffness of the pancreatic lesions in the head of 6.03 ± 0.42 kPa, body of 5.57 ± 0.82 kPa, and tail of 5.9 ± 1.9 kPa were also higher than those of corresponding segments of the normal volunteers (P = 0.0011, 0.0029, and 0.029, respectively). CONCLUSION: With the elastic belt, miscalculation of the pancreatic stiffness was reduced. MRE showed differences of stiffness between normal pancreas and pancreatic lesions.

Cystic apocrine ductal carcinoma in situ with increased EGFR expression, trisomy 7, and associated focal invasion.

A 71-year-old woman was admitted to our hospital with a lump in her right breast. Mammography revealed an internal high-density mass in the lower right breast, which was larger than it was 2 years ago. Considering the findings from ultrasonography, computed tomography, and cytology, an intracystic carcinoma could not be ruled out. The patient underwent excisional biopsy, which revealed an apocrine ductal carcinoma in situ (ADCIS) with focal invasive apocrine carcinoma (IAC). The diagnosis was based on morphology and immunohistochemistry (IHC), which was negative for the estrogen and progesterone receptors, and positive for the androgen receptor. Expression of the human epidermal growth factor receptor 2 and the epidermal growth factor receptor (EGFR) received an immunohistochemical score of 2+. Trisomy of chromosome 7, including multiple CEP 7 and EGFR signals, was observed in ADCIS by fluorescence in situ hybridization (FISH). IAC exhibited similar results for IHC and FISH. This is the first reported case showing trisomy 7 resulting in EGFR copy number gain and increased EGFR expression in ADCIS.

Detection of intrahepatic veno-venous shunts by three-dimensional venography using multidetector-row computed tomography during angiography.

PURPOSE: The hepatic vein (HV) can be removed during hepatectomy if there is an effective intrahepatic veno-venous shunt (vv-shunt). We evaluated the efficacy of vv-shunt detection by three-dimensional (3D) venography reconstructed from multidetector-row computed tomography (MDCT) during angiography. METHODS: 3D venography was reconstructed using computer software in 88 patients with intrahepatic tumors. RESULTS: We found that 12 patients had one shunt [4 right hepatic vein (RHV)-middle hepatic vein (MHV) and 12 RHV- inferior right hepatic vein (IRHV)] and 1 patient had 2 shunts (RHV-MHV and -IRHV), confirming a clinically efficient vv-shunt in 14.8% of the patients. In one patient with an RHV-IRHV shunt, the preserved RHV-IRHV shunt worked well and prevented congestion of the postero-caudal subsegment after central bisegmentectomy with partial resection of the RHV ventral trunk for huge hepatocellular carcinoma (HCC). CONCLUSIONS: Although the vv-shunt detection rate by 3D venography is low, a visualized vv-shunt proved to be efficient. Thus, invasive occlusion venography is avoidable if a vv-shunt is seen on 3D venography.

Preliminary study of standardized semiquantitative method for ultrasonographic breast composition assessment.

PURPOSE: To develop a classification tree via semiquantitative analysis for ultrasonographic breast composition assessment using routine breast ultrasonography examination images. METHODS: This study retrospectively enrolled 100 consecutive normal women who underwent screening mammography and supplemental ultrasonography. Based on sonographic breast composition, the patients' breasts were classified as nondense or dense, which were correlated with mammographic breast composition. Ultrasonographic breast composition was classified based on the fibroglandular tissue (FGT) thickness-to-subcutaneous fat and retromammary fat (FAT) thickness ratio. In addition, the presence of a high glandular tissue component (GTC) in FGT or the presence of evident fat lobules in FGT was investigated. The cutoff point between the nondense and dense breasts was calculated from the area under the curve (AUC). RESULTS: All cases with a high GTC were dense breasts, and all cases with evident fat lobules in the FGT were nondense breasts. The AUC of the FGT thickness-to-FAT ratio of all cases, the group without a high GTC, the group without evident fat lobules in the FGT, and the group without a high GTC or evident fat lobules in the FGT were 0.93, 0.94, 0.99, and 1, respectively. CONCLUSION: The presence of a high GTC indicated dense breasts, and the presence of evident fat lobules in the FGT represented nondense breasts. For the remaining cases, the cutoff point of the FGT thickness-to-FAT thickness ratio was 0.93 for ultrasonographic two-grade scale breast composition assessment with 100% accuracy.

Anomalous arterial ramification in the right liver.

PURPOSE: The aim of this study was to investigate whether individual arterial and portal venous division during hepatectomy is always safe by examining the presence of the anomalous arterial ramification in the right liver. METHODS: The ramifications of the right hepatic artery (RHA) were investigated by three-dimensional (3D) reconstruction imaging using a computer software program in 87 patients undergoing computed tomography during angiography as a preoperative assessment of intrahepatic tumors. RESULTS: The anterior view showed that the RHA bifurcated into the anterior and posterior sector arteries at the hilum in 76 patients. Sector-intersecting arteries from the posterior to the anterior sector and vice versa were found in 7 and 4 of those patients, respectively. The RHA in the other 11 patients was divided in a complex manner into more than 2 arteries: e.g., the first branch to the cranial part of the posterior sector, the second to the anterior sector, and the third to the caudal part of the posterior sector. A total of 22 patients showed anomalous ramification of RHA. CONCLUSION: Preoperative observation of the hepatic artery by 3D imaging is very useful to detect anomalous ramification. Arterial dissection during the intrafascial approach should be cautiously performed based on the 3D images.

Comparisons between artificial intelligence computer-aided detection synthesized mammograms and digital mammograms when used alone and in combination with tomosynthesis images in a virtual screening setting.

PURPOSE: To compare the reader performance of artificial intelligence computer-aided detection synthesized mammograms (AI CAD SM) with that of digital mammograms (DM) when used alone or in combination with digital breast tomosynthesis (DBT) images. MATERIALS AND METHODS: This retrospective multireader (n = 4) study compared the reader performances in 388 cases (84 cancer, 83 benign, and 221 normal or benign cases). The overall accuracy of the breast-based assessment was determined by four radiologists using two sequential reading modes: DM followed by DM + DBT; and AI CAD SM followed by AI CAD SM + DBT. Each breast was rated by each reader using five-category ratings, where 3 or higher was considered positive. The area under the receiver-operating characteristic curve (AUC) and reading time were evaluated. RESULTS: The mean AUC values for DM, AI CAD SM, DM + DBT, and AI CAD SM + DBT were 0.863, 0.895, 0.886, and 0.902, respectively. The mean AUC of AI CAD SM was significantly higher (P < 0.0001) than that of DM. The mean AUC of AI CAD SM + DBT was higher than that of DM + DBT (P = 0.094). A significant reduction in the reading time was observed after using AI CAD SM + DBT when compared with that after using DM + DBT (P < 0.001). CONCLUSION: AI CAD SM + DBT might prove more effective than DM + DBT in a screening setting because of its lower radiation dose, noninferiority, and shorter reading time compared to DM + DBT.

Artificial intelligence computer-aided detection enhances synthesized mammograms: comparison with original digital mammograms alone and in combination with tomosynthesis images in an experimental setting.

BACKGROUND: It remains unclear whether original full-field digital mammograms (DMs) can be replaced with synthesized mammograms in both screening and diagnostic settings. To compare reader performance of artificial intelligence computer-aided detection synthesized mammograms (AI CAD SMs) with that of DM alone or in combination with digital breast tomosynthesis (DBT) images in an experimental setting. METHODS: We compared the performance of multireader (n = 4) and reading multicase (n = 388), in 84 cancers, 83 biopsy-proven benign lesions, and 221 normal or benign cases with negative results after 1-year follow-up. Each reading was independently interpreted with four reading modes: DM, AI CAD SM, DM + DBT, and AI CAD SM + DBT. The accuracy of probability of malignancy (POM) and five-category ratings were evaluated using areas under the receiver operating characteristic curve (AUC) in the random-reader analysis. RESULTS: The mean AUC values based on POM for DM, AI CAD SM, DM + DBT, and AI CAD SM + DBT were 0.871, 0.902, 0.895, and 0.909, respectively. The mean AUC of AI CAD SM was significantly higher (P = 0.002) than that of DM. For calcification lesions, the sensitivity of SM and DM did not differ significantly (P = 0.204). The mean AUC for AI CAD SM + DBT was higher than that of DM + DBT (P = 0.082). ROC curves based on the five-category ratings showed similar proximity of the overall performance levels. CONCLUSIONS: AI CAD SM alone was superior to DM alone. Also, AI CAD SM + DBT was superior to DM + DBT but not statistically significant.

A case of paraspinal arteriovenous fistula in the lumbar spinal body assessed with time resolved three-dimensional phase contrast MRI.

A 93-year-old female with a paraspinal arteriovenous fistula (AVF) occurred within the lumbar spinal vertebral body was assessed with time resolved three-dimensional (3D) phase-contrast MRI (4D-Flow) on 1.5 Tesla MR scanner (GE Healthcare). The 3D vector field, streamlines, and pathlines analyses demonstrated uni-directional flow from the aorta to the large vascular cavity in the lumbar vertebral body by means of the lumbar artery as well as dilated paravertebral veins as drainers, which confirmed AVF, not aortic pseudoaneurysm. The 4D-Flow also showed an added value in planned endovascular surgery concerning localization of the precise shunting point and the shunting volume quantification.

Comparison of 3- and 1.5-T dynamic breast MRI for visualization of spiculated masses previously identified using mammography.

OBJECTIVE: The purpose of this article is to determine the effectiveness of MRI for visualizing spiculated breast cancer lesions that were previously identified using mammography and to compare the diagnostic quality of 3- and 1.5-T dynamic MRI by assessing the visualization of spiculation in such lesions. MATERIALS AND METHODS: One hundred twenty MRI studies of breast cancers clearly identified as spiculated masses using mammography (71 MRI studies at 3 T that included both bilateral axial and unilateral sagittal images and 49 MRI studies at 1.5 T that included bilateral axial images only) were independently reviewed by three radiologists. The three different radiologists scored the visualization of the spiculation with respect to 3-T sagittal, 3-T axial, or 1.5-T axial images. RESULTS: The diagnostic quality of sagittal 3-T dynamic MRI studies, as determined by assessing the visualization of spiculation, was significantly better than that of axial 3-T (p = 0.009) and 1.5-T (p = 0.004) studies. For small (< 1 cm) lesions, the diagnostic quality of sagittal 3-T studies determined by assessing the visualization of spiculation was significantly better than that of axial 1.5-T studies (p = 0.029). CONCLUSION: Unilateral sagittal in-plane and through-plane high-spatial-resolution 3-T images can offer particularly higher spatial resolution for improved assessment of spiculation than do axial in-plane high-spatial-resolution images obtained at 1.5 and 3 T.

Double neuroendocrine ductal carcinomas in situ coexisting with a background of diffuse idiopathic neuroendocrine cell hyperplasia of breast: a case report and hypothesis of neuroendocrine tumor development.

This article reports the case of a 72-year-old woman with two nodules of neuroendocrine (NE) ductal carcinoma in situ coexistent with a background of NE cell hyperplasia. Both tumors, 15 and 3 mm in size, were incidentally revealed on computed tomography without any apparent clinical symptoms. The tumors showed similar histological features, and more than 50% of the tumor cells patchily expressed NE markers, such as chromogranin A, synaptophysin, CD56, and somatostatin receptor type 2. The surrounding nontumor ductal cells also showed spotty or linear positivity for NE markers in contrast to the cells of normal atrophic breasts, which rarely present with NE cells. Moreover, focal mucin production was also observed in the peripheral ducts. It is hypothesized that idiopathic breast NE cell hyperplasia with multiple small nests of NE cells may extend to form a true mass of NE neoplasms.

Peripancreatic arterial anatomy analyzed by 3-dimensional multidetector-row computed tomography.

BACKGROUND/AIMS: Since the anatomy of the peripancreatic vessel system is complex, it is important to preoperatively clarify the running aspects of such vessels, especially when pancreatoduodenectomy is performed. METHODOLOGY: In 166 patients undergoing multidetector-row computed tomography, peripancreatic vessels were three-dimensionally reconstructed using computer software. RESULTS: The dorsal pancreatic artery branched from the splenic artery (45.4%), common hepatic artery (24.8%), superior mesenteric artery (SMA, 15.6%), celiac axis (9.9%) and other arteries such as the middle colic artery (4.3%). Branching of the inferior pancreatoduodenal artery (IPDA) was categorized into two types: a single main IPDA branching from one artery, such as the first jejunal artery (J1a, 55.2%) and SMA (25.1%) and two IPDAs branching from one artery (J1a, 7.0% or SMA, 2.8%) or separately from two arteries (3.5%). Most IPDAs (129 of identified 168 IPDAs) ran behind the SMA at the right edge of the SMA. In 52 patients, superior mesenteric vein tributaries ran above the SMA and mask the IPDA's ramification. CONCLUSIONS: Peripancreatic vessel anatomy is very complex. The preoperative 3D arteriography and portography enables us to obtain precise information about peripancreatic vessels.

Water and lipid content of breast tissue measured by six-wavelength time-domain diffuse optical spectroscopy.

Significance: The water and lipid content of normal breast tissue showed mammary gland characteristics with less influence from the chest wall using six-wavelength time-domain diffuse optical spectroscopy (TD-DOS) in a reflectance geometry. Aim: To determine the depth sensitivity of a six-wavelength TD-DOS system and evaluate whether the optical parameters in normal breast tissue can distinguish dense breasts from non-dense breasts. Approach: Measurements were performed in normal breast tissue of 37 breast cancer patients. We employed a six-wavelength TD-DOS system to measure the water and lipid content in addition to the hemoglobin concentration. The breast density in mammography and optical parameters were then compared. Results: The depth sensitivity of the system for water and lipid content was estimated to be ∼15 mm. Our findings suggest that the influence of the chest wall on the water content is weaker than that on the total hemoglobin concentration. In data with evaluation conditions, the water content was significantly higher (p < 0.001) and the lipid content was significantly lower (p < 0.001) in dense breast tissue. The water and lipid content exhibited a high sensitivity and specificity to distinguish dense from non-dense breasts in receiver-operating-characteristic curve analysis. Conclusions: With less influence from the chest wall, the water and lipid content of normal breast tissue measured by a reflectance six-wavelength TD-DOS system, together with ultrasonography, can be applied to distinguish dense from non-dense breasts.

Daikenchuto increases blood flow in the superior mesenteric artery in humans: A comparison study between four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction magnetic resonance imaging and Doppler ultrasound.

Respiratory-gated four-dimensional phase-contrast vastly undersampled isotropic projection reconstruction (4D PC-VIPR) is magnetic resonance (MR) imaging technique that enables analysis of vascular morphology and hemodynamics in a single examination using cardiac phase resolved 3D phase-contrast magnetic resonance imaging. The present study aimed to assess the usefulness of 4D PC-VIPR for the superior mesenteric artery (SMA) flowmetry before and after flow increase was induced by the herbal medicine Daikenchuto (TJ-100) by comparing it with Doppler ultrasound (DUS) as a current standard. Twenty healthy volunteers were enrolled in this prospective single-arm study. The peak cross-sectionally averaged velocity was measured by 4D PC-VIPR, peak velocity was measured by DUS, and flow volume (FV) of SMA and aorta were measured by 4D PC-VIPR and DUS 25 min before and after the peroral administration of TJ-100. The peak cross-sectionally averaged velocity, peak velocity, and FV of SMA measured by 4D PC-VIPR and DUS significantly increased after administration of TJ-100 (4D PC-VIPR: the peak cross-sectionally averaged velocity; p = 0.004, FV; p = 0.035, DUS: the peak velocity; p = 0.003, FV; p = 0.010). Furthermore, 4D PC-VIPR can analyze multiple blood vessels simultaneously. The ratio of the SMA FV to the aorta, before and after oral administration on the 4D PC-VIPR test also increased (p = 0.015). The rate of change assessed by 4D PC-VIPR and DUS were significantly correlated (the peak cross-sectionally averaged velocity and peak velocity: r = 0.650; p = 0.005, FV: r = 0.659; p = 0.004). Retrospective 4D PC-VIPR was a useful modality for morphological and hemodynamic analysis of SMA.

Duodenal adenocarcinoma successfully diagnosed with transabdominal ultrasonography.

Adenocarcinoma arising from the duodenum is relatively rare. Diagnosis of this disease at an early stage is difficult because its symptoms are usually nonspecific. We herein present a case in which duodenal adenocarcinoma was successfully found by transabdominal ultrasonography. Under ultrasonography, the tumor was located in the proximal duodenum apart from the papilla of Vater, and the serosa was intact. Other diagnostic modalities showed no evidence of adjacent organ invasion or distant metastasis. Therefore, pancreatoduodenectomy was performed and the postoperative course was uneventful. The ultrasonographic findings corresponded well with the pathological diagnosis. The following three procedures were essential in this case: systematic scanning of the digestive tract to determine the location of the lesion, graded compression ultrasound to remove air bubbles from the region of interest, and precise observation of the intestinal walls using proper transducers. The precise and skillful performance of transabdominal ultrasonography using a suitable device can help to diagnose duodenal adenocarcinoma, a rare malignancy.

Stable tissue-simulating phantoms with various water and lipid contents for diffuse optical spectroscopy.

We introduced a method for producing solid phantoms with various water-to-lipid ratios that can simulate the absorption, and to some extent the scattering characteristics of human breast tissue. We also achieved phantom stability for a minimum of one month by solidifying the emulsion phantoms. The characteristics of the phantoms were evaluated using the six-wavelength time-domain diffuse optical spectroscopy (TD-DOS) system we developed to measure water and lipid contents and hemoglobin concentration. The TD-DOS measurements were validated with a magnetic resonance imaging system.

Atypically enhanced cavernous hemangiomas of the liver: centrifugal enhancement does not preclude the diagnosis of hepatic hemangioma.

The imaging features of an atypically enhanced hepatic hemangioma have not been well described in the literature, and the presence of such atypia may sometimes cause clinical problems in the differential diagnosis. Herein, we report a case of hepatic hemangioma demonstrating a previously unreported atypical enhancement pattern. On dynamic computed tomography during hepatic arteriography, a centrifugal enhancement pattern and subsequent peritumoral ring-shaped enhancement mimicking corona enhancement were found in cavernous hemangiomas of the liver in a 68-year-old Japanese man. Histopathological diagnosis of cavernous hemangioma of the liver was made on a biopsy specimen. Considering the importance of differentiating benign hepatic tumor from various forms of malignancy, radiologists and hepatologists should be aware of rare enhancement patterns sometimes seen in hepatic hemangioma. Establishing knowledge of the entire spectrum of atypical hepatic hemangioma may benefit the rational approach to future cases.

Effect of the chest wall on the measurement of hemoglobin concentrations by near-infrared time-resolved spectroscopy in normal breast and cancer.

BACKGROUND: Optical imaging and spectroscopy using near-infrared light have great potential in the assessment of tumor vasculature. We previously measured hemoglobin concentrations in breast cancer using a near-infrared time-resolved spectroscopy system. The purpose of the present study was to evaluate the effect of the chest wall on the measurement of hemoglobin concentrations in normal breast tissue and cancer. METHODS: We measured total hemoglobin (tHb) concentration in both cancer and contralateral normal breast using a near-infrared time-resolved spectroscopy system in 24 female patients with breast cancer. Patients were divided into two groups based on menopausal state. The skin-to-chest wall distance was determined using ultrasound images obtained with an ultrasound probe attached to the spectroscopy probe. RESULTS: The apparent tHb concentration of normal breast increased when the skin-to-chest wall distance was less than 20 mm. The tHb concentration in pre-menopausal patients was higher than that in post-menopausal patients. Although the concentration of tHb in cancer tissue was statistically higher than that in normal breast, the contralateral normal breast showed higher tHb concentration than cancer in 9 of 46 datasets. When the curves of tHb concentrations as a function of the skin-to-chest wall distance in normal breast were applied for pre- and post-menopausal patients separately, all the cancer lesions plotted above the curves. CONCLUSIONS: The skin-to-chest wall distance affected the measurement of tHb concentration of breast tissue by near-infrared time-resolved spectroscopy. The tHb concentration of breast cancer tissue was more precisely evaluated by considering the skin-to-chest wall distance.

Breast cancer metastatic to the kidney with renal vein involvement.

The common sites of breast cancer metastases include bones, lung, brain, and liver. Renal metastasis from the breast is rare. We report a case of breast cancer metastatic to the kidney with extension into the renal vein. A 40-year-old woman had undergone left mastectomy for breast cancer at the age of 38. A gastric tumor, which was later proved to be metastasis from breast cancer, was detected by endoscopy. Computed tomography performed for further examination of the gastric tumor revealed a large left renal tumor with extension into the left renal vein. It mimicked a primary renal tumor. Percutaneous biopsy of the renal tumor confirmed metastasis from breast cancer. Surgical intervention of the stomach and the kidney was avoided, and she was treated with systemic chemotherapy. Breast cancer metastatic to the kidney may present a solitary renal mass with extension into the renal vein, which mimics a primary renal tumor.