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Trovato P, Simonetti I, Morrone A, Fusco R, Setola SV, Giacobbe G, Brunese MC, Pecchi A, Triggiani S, Pellegrino G, Petralia G, Sica G, Petrillo A, Granata V. Scientific Status Quo of Small Renal Lesions: Diagnostic Assessment and Radiomics. J Clin Med 2024; 13:547. [PMID: 38256682 PMCID: PMC10816509 DOI: 10.3390/jcm13020547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/05/2024] [Accepted: 01/16/2024] [Indexed: 01/24/2024] Open
Abstract
Background: Small renal masses (SRMs) are defined as contrast-enhanced renal lesions less than or equal to 4 cm in maximal diameter, which can be compatible with stage T1a renal cell carcinomas (RCCs). Currently, 50-61% of all renal tumors are found incidentally. Methods: The characteristics of the lesion influence the choice of the type of management, which include several methods SRM of management, including nephrectomy, partial nephrectomy, ablation, observation, and also stereotactic body radiotherapy. Typical imaging methods available for differentiating benign from malignant renal lesions include ultrasound (US), contrast-enhanced ultrasound (CEUS), computed tomography (CT), and magnetic resonance imaging (MRI). Results: Although ultrasound is the first imaging technique used to detect small renal lesions, it has several limitations. CT is the main and most widely used imaging technique for SRM characterization. The main advantages of MRI compared to CT are the better contrast resolution and tissue characterization, the use of functional imaging sequences, the possibility of performing the examination in patients allergic to iodine-containing contrast medium, and the absence of exposure to ionizing radiation. For a correct evaluation during imaging follow-up, it is necessary to use a reliable method for the assessment of renal lesions, represented by the Bosniak classification system. This classification was initially developed based on contrast-enhanced CT imaging findings, and the 2019 revision proposed the inclusion of MRI features; however, the latest classification has not yet received widespread validation. Conclusions: The use of radiomics in the evaluation of renal masses is an emerging and increasingly central field with several applications such as characterizing renal masses, distinguishing RCC subtypes, monitoring response to targeted therapeutic agents, and prognosis in a metastatic context.
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Affiliation(s)
- Piero Trovato
- Radiology Division, Istituto Nazionale Tumori-IRCCS-Fondazione G. Pascale, 80131 Naples, Italy; (P.T.); (I.S.); (S.V.S.); (A.P.); (V.G.)
| | - Igino Simonetti
- Radiology Division, Istituto Nazionale Tumori-IRCCS-Fondazione G. Pascale, 80131 Naples, Italy; (P.T.); (I.S.); (S.V.S.); (A.P.); (V.G.)
| | - Alessio Morrone
- Division of Radiology, Università degli Studi della Campania Luigi Vanvitelli, 80138 Naples, Italy;
| | - Roberta Fusco
- Medical Oncology Division, Igea SpA, 80013 Naples, Italy
- Italian Society of Medical and Interventional Radiology (SIRM), SIRM Foundation, Via della Signora 2, 20122 Milan, Italy
| | - Sergio Venanzio Setola
- Radiology Division, Istituto Nazionale Tumori-IRCCS-Fondazione G. Pascale, 80131 Naples, Italy; (P.T.); (I.S.); (S.V.S.); (A.P.); (V.G.)
| | - Giuliana Giacobbe
- General and Emergency Radiology Department, “Antonio Cardarelli” Hospital, 80131 Naples, Italy;
| | - Maria Chiara Brunese
- Diagnostic Imaging Section, Department of Medical and Surgical Sciences & Neurosciences, University of Molise, 86100 Campobasso, Italy;
| | - Annarita Pecchi
- Department of Radiology, University of Modena and Reggio Emilia, 41121 Modena, Italy;
| | - Sonia Triggiani
- Postgraduate School of Radiodiagnostics, University of Milan, 20122 Milan, Italy; (S.T.); (G.P.)
| | - Giuseppe Pellegrino
- Postgraduate School of Radiodiagnostics, University of Milan, 20122 Milan, Italy; (S.T.); (G.P.)
| | - Giuseppe Petralia
- Department of Medical Imaging and Radiation Sciences, IEO European Institute of Oncology IRCCS, Via Ripamonti 435, 20141 Milan, Italy;
| | - Giacomo Sica
- Radiology Unit, Monaldi Hospital, Azienda Ospedaliera dei Colli, 80131 Naples, Italy;
| | - Antonella Petrillo
- Radiology Division, Istituto Nazionale Tumori-IRCCS-Fondazione G. Pascale, 80131 Naples, Italy; (P.T.); (I.S.); (S.V.S.); (A.P.); (V.G.)
| | - Vincenza Granata
- Radiology Division, Istituto Nazionale Tumori-IRCCS-Fondazione G. Pascale, 80131 Naples, Italy; (P.T.); (I.S.); (S.V.S.); (A.P.); (V.G.)
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Remer EM. Mimics and Pitfalls in Renal Imaging. Radiol Clin North Am 2020; 58:885-896. [PMID: 32792121 DOI: 10.1016/j.rcl.2020.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
There are several potential pitfalls that radiologists face when interpreting images of the kidneys. Some result from image acquisition and can arise from the imaging equipment or imaging technique, whereas others are patient related. Another category of pitfalls relates to image interpretation. Some difficulties stem from methods to detect enhancement after contrast administration, whereas others are benign entities that can mimic a renal tumor. Finally, interpretation and diagnosis of fat-containing renal masses may be tricky due to the complexities discerning the pattern of fat within a mass and how that translates to an accurate diagnosis.
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Affiliation(s)
- Erick M Remer
- Imaging Institute and Glickman Urological and Kidney Institute, Cleveland Clinic, 9500 Euclid Avenue, A21, Cleveland, OH 44195, USA.
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3
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Krishna S, Leckie A, Kielar A, Hartman R, Khandelwal A. Imaging of Renal Cancer. Semin Ultrasound CT MR 2020; 41:152-169. [DOI: 10.1053/j.sult.2019.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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4
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Ye J, Xu Q, Wang SA, Zheng J, Zhu QQ, Dou WQ. Differentiation between fat-poor angiomyolipoma and clear cell renal cell carcinoma: qualitative and quantitative analysis using arterial spin labeling MR imaging. Abdom Radiol (NY) 2020; 45:512-519. [PMID: 31705246 DOI: 10.1007/s00261-019-02303-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
PURPOSE To assess the diagnostic effectiveness of arterial spin labeling (ASL) MR imaging in differentiating fat-poor AML from clear cell renal cell carcinoma (ccRCC). METHODS In this prospective study, 29 ccRCC patients and 9 fat-poor AML patients underwent routine anatomical MRI and ASL at 3T before surgery after signing written informed consent form. For each tumor, tumor blood flow (TBF) was measured in a region of interest (ROI) which was positioned to outline the edge of the target lesions on ASL perfusion maps. Additionally, the mean TBF values were obtained by standardizing the TBF using a blood flow measurement in the reference ROI. Moreover, a cluster containing more than 10 voxels was chosen from the renal cortex and medulla area in normal contralateral kidney as a reference ROI to calculate tumor-to-cortex ratio and tumor-to-medulla ratio. Independent sample t test was used to examine the alteration among the groups of fat-poor AML and ccRCC. ASL images were together analyzed by two radiologists to assess the following characteristics of the renal mass: predominant SI in the tumor on ASL images was lower than, as same as, or higher than SI of the cortex. For qualitative variables, Fisher's exact test was employed to compare the proportions of these two groups. The sensitivity, specificity ,and accuracy required for discrimination of fat-poor AML from ccRCC were quantified using receiver operating characteristic (ROC) curve. The corresponding optimal cutoff value was obtained for each parameter as well. RESULTS The TBF value was significantly higher in ccRCC group than that in fat-poor AML (270.49 ± 78.88 ml/100 g/min vs. 146.68 ± 47.21 ml/100 g/min; P < 0.01). Both tumor-to-cortex and tumor-to-medulla ratios were notably higher in ccRCC group compared with those in fat-poor AML group (1.22 ± 0.26 vs. 0.74 ± 0.14, 3.13 ± 0.94 vs. 1.77 ± 0.55; P < 0.05). The values of area under the ROC curve (AUC) for TBF, tumor-to-cortex ratio, and tumor-to-medulla ratio were 0.931, 0.964, and 0.900, respectively. No significant difference in AUC values among these three measurements was observed. For qualitative variables, the SI of fat-poor AML was equal to or slightly lower than that of renal medulla and the SI of ccRCC was found to be higher than renal cortex in ASL. CONCLUSION ASL MRI performs well in differentiating fat-poor AML from ccRCC in both qualitative and quantitative analyses.
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Affiliation(s)
- Jing Ye
- Department of Medical Imaging, Clinic Medical School, Northern Jiangsu Province Hospital, Yangzhou University, Yangzhou, 225000, Jiangsu Province, China
| | - Qing Xu
- Department of Medical Imaging, Clinic Medical School, Northern Jiangsu Province Hospital, Yangzhou University, Yangzhou, 225000, Jiangsu Province, China.
| | - Shou-An Wang
- Department of Medical Imaging, Clinic Medical School, Northern Jiangsu Province Hospital, Yangzhou University, Yangzhou, 225000, Jiangsu Province, China
| | - Jin Zheng
- Department of Medical Imaging, Clinic Medical School, Northern Jiangsu Province Hospital, Yangzhou University, Yangzhou, 225000, Jiangsu Province, China
| | - Qing-Qiang Zhu
- Department of Medical Imaging, Clinic Medical School, Northern Jiangsu Province Hospital, Yangzhou University, Yangzhou, 225000, Jiangsu Province, China
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An overview of non-invasive imaging modalities for diagnosis of solid and cystic renal lesions. Med Biol Eng Comput 2019; 58:1-24. [DOI: 10.1007/s11517-019-02049-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 09/17/2019] [Indexed: 12/22/2022]
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6
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Schieda N, Davenport MS, Pedrosa I, Shinagare A, Chandarana H, Curci N, Doshi A, Israel G, Remer E, Wang J, Silverman SG. Renal and adrenal masses containing fat at MRI: Proposed nomenclature by the society of abdominal radiology disease-focused panel on renal cell carcinoma. J Magn Reson Imaging 2019; 49:917-926. [PMID: 30693607 DOI: 10.1002/jmri.26542] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2018] [Revised: 09/16/2018] [Accepted: 09/17/2018] [Indexed: 12/15/2022] Open
Abstract
This article proposes a consensus nomenclature for fat-containing renal and adrenal masses at MRI to reduce variability, improve understanding, and enhance communication when describing imaging findings. The MRI appearance of "macroscopic fat" occurs due to a sufficient number of aggregated adipocytes and results in one or more of: 1) intratumoral signal intensity (SI) loss using fat-suppression techniques, or 2) chemical shift artifact of the second kind causing linear or curvilinear India-ink (etching) artifact within or at the periphery of a mass at macroscopic fat-water interfaces. "Macroscopic fat" is most commonly observed in adrenal myelolipoma and renal angiomyolipoma (AML) and only rarely encountered in other adrenal cortical tumors and renal cell carcinomas (RCC). Nonlinear noncurvilinear signal intensity loss on opposed-phase (OP) compared with in-phase (IP) chemical shift MRI (CSI) may be referred to as "microscopic fat" and is due to: a) an insufficient amount of adipocytes, or b) the presence of fat within tumor cells. Determining whether the signal intensity loss observed on CSI is due to insufficient adipocytes or fat within tumor cells cannot be accomplished using CSI alone; however, it can be inferred when other imaging features strongly suggest a particular diagnosis. Fat-poor AML are homogeneously hypointense on T2 -weighted (T2 W) imaging and avidly enhancing; signal intensity loss at OP CSI is uncommon, but when present is usually focal and is caused by an insufficient number of adipocytes within adjacent voxels. Conversely, clear-cell RCC are heterogeneously hyperintense on T2 W imaging and avidly enhancing, with the signal intensity loss observed on OP CSI being typically diffuse and due to fat within tumor cells. Adrenal adenomas, adrenal cortical carcinoma, and adrenal metastases from fat-containing primary malignancies also show signal intensity loss on OP CSI due to fat within tumor cells and not from intratumoral adipocytes. Level of Evidence: 5 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2019;49:917-926.
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Affiliation(s)
- Nicola Schieda
- Department of Medical Imaging, From the University of Ottawa, Ottawa Hospital, Ottawa, Ontario, Canada
| | | | - Ivan Pedrosa
- Department of Radiology, UT Southwestern, Dallas, Texas, USA
| | - Atul Shinagare
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Hersch Chandarana
- Department of Radiology, NYU School of Medicine, New York, New York, USA
| | - Nicole Curci
- Department of Radiology, Michigan University, Ann Arbor, Michigan, USA
| | - Ankur Doshi
- Department of Radiology, NYU School of Medicine, New York, New York, USA
| | - Gary Israel
- Department of Radiology, Yale University, New Haven, Connecticut, USA
| | - Erick Remer
- Department Radiology and Diagnostic Imaging, Cleveland Clinic, Cleveland, Ohio, USA
| | - Jane Wang
- Department of Radiology, UCSF, San Francisco, California, USA
| | - Stuart G Silverman
- Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts, USA
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Evaluation of a free-breathing respiratory-triggered (Navigator) 3-D T1-weighted (T1W) gradient recalled echo sequence (LAVA) for detection of enhancement in cystic and solid renal masses. Eur Radiol 2018; 29:2507-2517. [PMID: 30506224 DOI: 10.1007/s00330-018-5839-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 09/15/2018] [Accepted: 10/17/2018] [Indexed: 01/14/2023]
Abstract
OBJECTIVES To evaluate free-breathing Navigator-triggered 3-D T1-weighted MRI (NAV-LAVA) compared to breath-hold (BH)-LAVA among cystic and solid renal masses. MATERIALS AND METHODS With an IRB waiver, 44 patients with 105 renal masses (71 non-enhancing cysts and 14 cystic and 20 solid renal masses) underwent MRI between 2016 and 2017 where BH-LAVA and NAV-LAVA were performed. Subtraction images were generated for BH-LAVA and NAV-LAVA using pre- and 3-min post-gadolinium-enhanced images and were evaluated by two blinded radiologists for overall image quality, image sharpness, motion artifact, and quality of subtraction (using 5-point Likert scales) and presence/absence of enhancement. Percentage signal intensity change (Δ%SI) = ([SI.post-gadolinium-SI.pre-gadolinium]/SI.pre-gadolinium)*100, was measured on BH-LAVA and NAV-LAVA. Likert scores were compared using Wilcoxon's sign-rank test and accuracy for detection of enhancement compared using receiver operator characteristic (ROC) analysis. RESULTS Overall image quality (p = 0.002-0.141), image sharpness (p = 0.002-0.031), and motion artifact were better (p = 0.002) comparing BH-LAVA to NAV-LAVA for both radiologists; however, quality of image subtraction did not differ between groups (p = 0.09-0.14). Sensitivity/specificity/area under ROC curve for enhancement in cystic and solid renal masses using subtraction and %SIΔ were (1) BH-LAVA: 64.7%/98.6%/0.82 (radiologist 1), 61.8%/95.8%/0.79 (radiologist 2), and 70.6%/81.7%/0.76 (%SIΔ) versus 2) NAV-LAVA: 58.8%/95.8%/0.79 (radiologist 1, p = 0.16), 58.8%/88.7%/0.73 (radiologist 2, p = 0.37), and 73.5%/76.1%/0.75 (%SIΔ, p = 0.74). CONCLUSIONS NAV-LAVA showed similar quality of subtraction and ability to detect enhancement compared to BH-LAVA in renal masses albeit with lower image quality, image sharpness, and increased motion artifact. NAV-LAVA may be considered in renal MRI for patients where BH is suboptimal. KEY POINTS • Free-breathing Navigator (NAV) 3-D subtraction MRI is comparable to breath-hold (BH) images. • Accuracy for subjective and quantitative diagnosis of enhancement in renal masses on NAV 3-D T1W is comparable to BH MRI. • NAV 3-D T1W renal MRI is useful in patients who may not be able to adequately BH.
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8
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Schieda N, Lim RS, McInnes MDF, Thomassin I, Renard-Penna R, Tavolaro S, Cornelis FH. Characterization of small (<4cm) solid renal masses by computed tomography and magnetic resonance imaging: Current evidence and further development. Diagn Interv Imaging 2018; 99:443-455. [PMID: 29606371 DOI: 10.1016/j.diii.2018.03.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 03/07/2018] [Indexed: 12/15/2022]
Abstract
Diagnosis of renal cell carcinomas (RCC) subtypes on computed tomography (CT) and magnetic resonance imaging (MRI) is clinically important. There is increased evidence that confident imaging diagnosis is now possible while standardization of the protocols is still required. Fat-poor angiomyolipoma show homogeneously increased unenhanced attenuation, homogeneously low signal on T2-weighted MRI and apparent diffusion coefficient (ADC) map, may contain microscopic fat and are classically avidly enhancing. Papillary RCC are also typically hyperattenuating and of low signal on T2-weighted MRI and ADC map; however, their gradual progressive enhancement after intravenous administration of contrast material is a differentiating feature. Clear cell RCC are avidly enhancing and may show intracellular lipid; however, these tumors are heterogeneous and are of characteristically increased signal on T2-weighted MRI. Oncocytomas and chromophobe tumors (collectively oncocytic neoplasms) show intermediate imaging findings on CT and MRI and are the most difficult subtype to characterize accurately; however, both show intermediately increased signal on T2-weighted with more gradual enhancement compared to clear cell RCC. Chromophobe tumors tend to be more homogeneous compared to oncocytomas, which can be heterogeneous, but other described features (e.g. scar, segmental enhancement inversion) overlap considerably between tumors. Tumor grade is another important consideration in small solid renal masses with emerging studies on both CT and MRI suggesting that high grade tumors may be separated from lower grade disease based upon imaging features.
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Affiliation(s)
- N Schieda
- Department of Medical Imaging, The Ottawa Hospital, The University of Ottawa, Ottawa, ON, Canada
| | - R S Lim
- Department of Medical Imaging, The Ottawa Hospital, The University of Ottawa, Ottawa, ON, Canada
| | - M D F McInnes
- Department of Medical Imaging, The Ottawa Hospital, The University of Ottawa, Ottawa, ON, Canada
| | - I Thomassin
- Sorbonne Université, Institut des Sciences du Calcul et des Données, Department of Radiology, Tenon Hospital - HUEP - APHP, 4 rue de la Chine, 75020 Paris, France
| | - R Renard-Penna
- Sorbonne Université, Institut des Sciences du Calcul et des Données, Department of Radiology, Tenon Hospital - HUEP - APHP, 4 rue de la Chine, 75020 Paris, France
| | - S Tavolaro
- Sorbonne Université, Institut des Sciences du Calcul et des Données, Department of Radiology, Tenon Hospital - HUEP - APHP, 4 rue de la Chine, 75020 Paris, France
| | - F H Cornelis
- Sorbonne Université, Institut des Sciences du Calcul et des Données, Department of Radiology, Tenon Hospital - HUEP - APHP, 4 rue de la Chine, 75020 Paris, France.
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Frequency of Angiomyolipomas Among Echogenic Nonshadowing Renal Masses (> 4 mm) Found at Ultrasound and the Utility of MRI for Diagnosis. AJR Am J Roentgenol 2017; 209:1074-1080. [DOI: 10.2214/ajr.16.17753] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Lim RS, Flood TA, McInnes MDF, Lavallee LT, Schieda N. Renal angiomyolipoma without visible fat: Can we make the diagnosis using CT and MRI? Eur Radiol 2017; 28:542-553. [PMID: 28779401 DOI: 10.1007/s00330-017-4988-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 04/22/2017] [Accepted: 07/11/2017] [Indexed: 12/12/2022]
Abstract
Renal angiomyolipomas without visible fat (AML.wovf) are benign masses that are incidentally discovered mainly in women. AML.wovf are typically homogeneously hyperdense on unenhanced CT without calcification or haemorrhage. Unenhanced CT pixel analysis is not useful for diagnosis. AML.wovf are characteristically homogeneously hypointense on T2-weighted (T2W)-MRI and apparent diffusion coefficient (ADC) maps. Despite early reports, only a minority of AML.wovf show signal intensity drop on chemical-shift MRI due to microscopic fat. AML.wovf most commonly show avid early enhancement with washout kinetics at contrast-enhanced CT and MRI. The combination of homogeneously low T2W and/or ADC signal intensity with avid early enhancement and washout is highly accurate for diagnosis of AML.wovf. KEY POINTS • AML.wovf are small incidental benign renal masses occurring mainly in women. • AML.wovf are homogeneously hyperdense with low signal on T2W-MRI and ADC map. • AML.wovf typically show avid early enhancement with washout kinetics. • Combining features on CT/MRI is accurate for diagnosis of AML.wovf.
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Affiliation(s)
- Robert S Lim
- Department of Medical Imaging, The Ottawa Hospital, The University of Ottawa, Ottawa, Ontario, Canada
| | - Trevor A Flood
- Department of Anatomical Pathology, The Ottawa Hospital, The University of Ottawa, Ottawa, Ontario, Canada
| | - Matthew D F McInnes
- Department of Medical Imaging, The Ottawa Hospital, The University of Ottawa, Ottawa, Ontario, Canada
| | - Luke T Lavallee
- Department of Surgery, Division of Urology, The Ottawa Hospital, The University of Ottawa, Ottawa, Ontario, Canada
| | - Nicola Schieda
- Department of Medical Imaging, The Ottawa Hospital, The University of Ottawa, Ottawa, Ontario, Canada.
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11
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Do Incidental Hyperechoic Renal Lesions Measuring Up to 1 cm Warrant Further Imaging? Outcomes of 161 Lesions. AJR Am J Roentgenol 2017; 209:346-350. [PMID: 28609114 DOI: 10.2214/ajr.16.17490] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the outcomes of hyperechoic renal lesions measuring 1 cm or less at ultrasound examination. MATERIALS AND METHODS This retrospective study included 161 hyperechoic renal lesions measuring 1 cm or less at ultrasound that were evaluated with follow-up ultrasound, CT, or MRI. Follow-up imaging examinations were reviewed to assess for definitive lesion characterization or size stability. RESULTS Follow-up included 11 unenhanced CT, 39 contrast-enhanced CT, 52 unenhanced and contrast-enhanced CT, two unenhanced MRI, 50 unenhanced and contrast-enhanced MRI, and 87 ultrasound examinations. At CT or MRI 58.4% of lesions were confirmed to be angiomyolipomas. At CT, one lesion represented a stone, and one a hyperdense cyst. At CT or MRI 11.8% of the lesions had no correlate; 3.1% were not visualized at follow-up ultrasound. An additional 23.6% were stable at 2-year follow-up imaging or beyond. Two lesions were evaluated with only contrast-enhanced CT less than 1 month after ultrasound, and the CT images did not show macroscopic fat or calcification or meet the criteria for a simple cyst. These lesions were considered indeterminate. One lesion in a 65-year-old man was imaged with unenhanced and contrast-enhanced CT 23 months after ultrasound, and the CT showed an increase in size, solid enhancement, and no macroscopic fat. This lesion was presumed to represent renal cell carcinoma. Overall, the one lesion presumed malignant and the two indeterminate lesions constituted 1.9% of the cohort. The other 98.1% of lesions were considered clinically insignificant. CONCLUSION Most hyperechoic renal lesions measuring 1 cm or smaller were clinically insignificant, suggesting that such lesions may not require additional imaging. Patient demographics, symptoms and risk factors for malignancy may help inform the decision to forgo follow-up imaging of such lesions.
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12
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Krishna S, Murray CA, McInnes MD, Chatelain R, Siddaiah M, Al-Dandan O, Narayanasamy S, Schieda N. CT imaging of solid renal masses: pitfalls and solutions. Clin Radiol 2017; 72:708-721. [PMID: 28592361 DOI: 10.1016/j.crad.2017.05.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 04/20/2017] [Accepted: 05/02/2017] [Indexed: 12/22/2022]
Abstract
Computed tomography (CT) remains the first-line imaging test for the characterisation of renal masses; however, CT has inherent limitations, which if unrecognised, may result in errors. The purpose of this manuscript is to present 10 pitfalls in the CT evaluation of solid renal masses. Thin section non-contrast enhanced CT (NECT) is required to confirm the presence of macroscopic fat and diagnosis of angiomyolipoma (AML). Renal cell carcinoma (RCC) can mimic renal cysts at NECT when measuring <20 HU, but are usually heterogeneous with irregular margins. Haemorrhagic cysts (HC) may simulate solid lesions at NECT; however, a homogeneous lesion measuring >70 HU is essentially diagnostic of HC. Homogeneous lesions measuring 20-70 HU at NECT or >20 HU at contrast-enhanced (CE) CT, are indeterminate, requiring further evaluation. Dual-energy CT (DECT) can accurately characterise these lesions at baseline through virtual NECT, iodine overlay images, or quantitative iodine concentration analysis without recalling the patient. A minority of hypo-enhancing renal masses (most commonly papillary RCC) show indeterminate or absent enhancement at multiphase CT. Follow-up, CE ultrasound or magnetic resonance imaging (MRI) is required to further characterise these lesions. Small (<3 cm) endophytic cysts commonly show pseudo-enhancement, which may simulate RCC; this can be overcome with DECT or MRI. In small (<4 cm) solid renal masses, 20% of lesions are benign, chiefly AML without visible fat or oncocytoma. Low-dose techniques may simulate lesion heterogeneity due to increased image noise, which can be ameliorated through the appropriate use of iterative reconstruction algorithms.
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Affiliation(s)
- S Krishna
- Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Canada
| | - C A Murray
- Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Canada
| | - M D McInnes
- Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Canada
| | - R Chatelain
- Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Canada
| | - M Siddaiah
- Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Canada
| | - O Al-Dandan
- Department of Radiology, University of Dammam, Dammam, Saudi Arabia
| | - S Narayanasamy
- Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Canada
| | - N Schieda
- Department of Medical Imaging, The Ottawa Hospital, University of Ottawa, Ottawa, Canada.
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13
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Shaaban AM, Rezvani M, Tubay M, Elsayes KM, Woodward PJ, Menias CO. Fat-containing Retroperitoneal Lesions: Imaging Characteristics, Localization, and Differential Diagnosis. Radiographics 2017; 36:710-34. [PMID: 27163589 DOI: 10.1148/rg.2016150149] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The complex anatomy of the retroperitoneum is reflected in the spectrum of neoplastic and nonneoplastic conditions that can occur in the retroperitoneum and appear as soft-tissue masses. The presence of fat within a retroperitoneal lesion is helpful in refining the differential diagnosis. Fat is easily recognized because of its characteristic imaging appearance. It typically is hyperechoic at ultrasonography and demonstrates low attenuation at computed tomography (-10 to -100 HU). Magnetic resonance imaging is a more ideal imaging modality because it has better soft-tissue image contrast and higher sensitivity for depicting (a) microscopic fat by using chemical shift imaging and (b) macroscopic fat by using fat-suppression techniques. Whether a lesion arises from a retroperitoneal organ or from the soft tissues of the retroperitoneal space (primary lesion) is determined by examining the relationship between the lesion and its surrounding structures. Multiple imaging signs help to determine the organ of origin, including the "beak sign," the "embedded organ sign," the "phantom (invisible) organ sign," and the "prominent feeding artery sign." Adrenal adenoma is the most common adrenal mass that contains microscopic fat, while myelolipoma is the most common adrenal mass that contains macroscopic fat. Other adrenal masses, such as pheochromocytoma and adrenocortical carcinoma, rarely contain fat. Renal angiomyolipoma is the most common fat-containing renal mass. Other fat-containing renal lesions, such as lipoma and liposarcoma, are rare. Fatty replacement of the pancreas and pancreatic lipomas are relatively common, whereas pancreatic teratomas are rare. Of the primary retroperitoneal fat-containing lesions, lipoma and liposarcoma are common, while other lesions are relatively rare. (©)RSNA, 2016.
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Affiliation(s)
- Akram M Shaaban
- From the Department of Radiology, University of Utah, 30 North 1900 East, 1A71, Salt Lake City, UT 84132 (A.M.S., M.R., P.J.W.); Imaging Department, U.S. Air Force Academy Medical Clinic, USAF Academy, Colorado Springs, Colo (M.T.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (K.M.E.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M.)
| | - Maryam Rezvani
- From the Department of Radiology, University of Utah, 30 North 1900 East, 1A71, Salt Lake City, UT 84132 (A.M.S., M.R., P.J.W.); Imaging Department, U.S. Air Force Academy Medical Clinic, USAF Academy, Colorado Springs, Colo (M.T.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (K.M.E.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M.)
| | - Marc Tubay
- From the Department of Radiology, University of Utah, 30 North 1900 East, 1A71, Salt Lake City, UT 84132 (A.M.S., M.R., P.J.W.); Imaging Department, U.S. Air Force Academy Medical Clinic, USAF Academy, Colorado Springs, Colo (M.T.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (K.M.E.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M.)
| | - Khaled M Elsayes
- From the Department of Radiology, University of Utah, 30 North 1900 East, 1A71, Salt Lake City, UT 84132 (A.M.S., M.R., P.J.W.); Imaging Department, U.S. Air Force Academy Medical Clinic, USAF Academy, Colorado Springs, Colo (M.T.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (K.M.E.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M.)
| | - Paula J Woodward
- From the Department of Radiology, University of Utah, 30 North 1900 East, 1A71, Salt Lake City, UT 84132 (A.M.S., M.R., P.J.W.); Imaging Department, U.S. Air Force Academy Medical Clinic, USAF Academy, Colorado Springs, Colo (M.T.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (K.M.E.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M.)
| | - Christine O Menias
- From the Department of Radiology, University of Utah, 30 North 1900 East, 1A71, Salt Lake City, UT 84132 (A.M.S., M.R., P.J.W.); Imaging Department, U.S. Air Force Academy Medical Clinic, USAF Academy, Colorado Springs, Colo (M.T.); Department of Radiology, University of Texas MD Anderson Cancer Center, Houston, Tex (K.M.E.); and Department of Radiology, Mayo Clinic, Scottsdale, Ariz (C.O.M.)
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Evaluation of T1-Weighted MRI to Detect Intratumoral Hemorrhage Within Papillary Renal Cell Carcinoma as a Feature Differentiating From Angiomyolipoma Without Visible Fat. AJR Am J Roentgenol 2016; 207:585-91. [DOI: 10.2214/ajr.16.16062] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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15
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Reply to "Solid Renal Cell Carcinomas With an Attenuation Similar to That of Water on Unenhanced CT". AJR Am J Roentgenol 2016; 206:W93. [PMID: 27043292 DOI: 10.2214/ajr.15.15981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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16
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Katabathina VS, Flaherty E, Prasad SR. Cross-Sectional Imaging of Renal Masses: Imaging Technique-Related Potential Pitfalls and Solutions. Semin Roentgenol 2016; 51:32-9. [PMID: 27020234 DOI: 10.1053/j.ro.2016.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Venkata S Katabathina
- Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX.
| | - Erin Flaherty
- Department of Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX
| | - Srinivasa R Prasad
- Department of Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX
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Kara O, Akca O, Zargar H, Andrade HS, Maurice MJ, Ramirez D, Caputo P, Haber GP, Kaouk JH, Stein RJ. Robotic Partial Nephrectomy in the Treatment of Renal Angiomyolipoma. J Endourol 2015; 30:275-9. [PMID: 26654096 DOI: 10.1089/end.2015.0624] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To present the experience and efficacy of Robotic Partial Nephrectomy (RPN) for the management of renal angiomyolipomas (AMLs) with regard to renal function preservation and perioperative outcomes. PATIENTS AND METHODS We retrospectively searched our RPN database for pathologically confirmed renal AML patients between 2006 and 2014. Clinical presentation, perioperative complications, and postoperative outcomes of the patients were analyzed. Preoperative imaging findings were reviewed to examine their ability to predict pathology of AML. RESULTS From 1005 RPN performed in our center during the study period, 53 patients met our inclusion criteria. The mean age at presentation was 54.1 (± 13) years, and 42 (79.2%) patients were female. Median tumor size was 2.8 (interquartile range [IQR], 1.8-4.6) cm. The indication for RPN was suspicious radiologic features for malignancy in 42 (79.2%) patients and acute retroperitoneal hemorrhage risk and pain in 11 (20.8%) patients who were found to have AML according to preoperative imaging. Mean estimated blood loss was 198 (± 194) mL, and 5 (9.4%) patients required blood transfusion. Postoperative complications occurred in 8 (15%) patients. Median estimated glomerular filtration rate within the latest follow-up was 86.9 (IQR, 69.7-100.1) mL/minute/1.73 m(2) with a median of 91% (IQR, 80.4-103) preservation. None of patients developed urinary fistula or pseudoaneurysm requiring second intervention. No local recurrences occurred with a median follow-up of 7 (IQR, 1-17) months. CONCLUSION Given the low complication rate and preservation of renal function after RPN for AML, it can be considered a reliable method for AML treatment. The majority of AMLs were not suspected based on preoperative imaging. Further diagnostic methods are needed to differentiate benign from malignant lesions.
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Affiliation(s)
- Onder Kara
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | - Oktay Akca
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | - Homayoun Zargar
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | - Hiury Silva Andrade
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | | | - Daniel Ramirez
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | - Peter Caputo
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | - George-Pascal Haber
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | - Jihad H Kaouk
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
| | - Robert J Stein
- Glickman Urological and Kidney Institute, Cleveland Clinic , Cleveland, Ohio
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Farrell C, Noyes SL, Tourojman M, Lane BR. Renal angiomyolipoma: preoperative identification of atypical fat-poor AML. Curr Urol Rep 2015; 16:12. [PMID: 25677233 DOI: 10.1007/s11934-015-0484-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The preoperative distinction between benign and malignant renal masses is a well-known radiographic diagnostic challenge. With angiomyolipoma (AML) and renal cell carcinoma (RCC) representing the most common benign and malignant renal parenchymal lesions, respectively, differentiating these two entities is especially important due to their vastly different treatments and prognoses. Renal AML is typically composed of smooth muscle cells, dysmorphic blood vessels, and varying amounts of adipose tissue. In most cases, "typical" AML can be diagnosed by identifying macroscopic fat with ultrasound, computed tomography, or magnetic resonance imaging. However, approximately 4-5 % of AML tumors have fat that is grossly undetectable by conventional techniques, precluding a straightforward diagnosis. The overlapping radiographic features between "atypical" or "fat-poor" AML and RCC, especially in smaller (<3-4 cm) lesions, lead many patients with benign AML to undergo unnecessary surgery for suspected RCC when the diagnosis is not established beforehand. This review presents the most recent studies and developments in preoperative evaluation of fat-poor AML.
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Affiliation(s)
- Crystal Farrell
- Grand Rapids Medical Education Partners, 1000 Monroe Avenue NE, Grand Rapids, MI, 49503, USA,
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19
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Schieda N, Dilauro M, Moosavi B, Hodgdon T, Cron GO, McInnes MDF, Flood TA. MRI evaluation of small (<4cm) solid renal masses: multivariate modeling improves diagnostic accuracy for angiomyolipoma without visible fat compared to univariate analysis. Eur Radiol 2015; 26:2242-51. [PMID: 26486936 DOI: 10.1007/s00330-015-4039-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/21/2015] [Accepted: 09/21/2015] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To assess MRI for diagnosis of angiomyolipoma without visible fat (AMLwvf). MATERIAL AND METHODS With IRB approval, a retrospective study in consecutive patients with contrast-enhanced (CE)-MRI and <4 cm solid renal masses from 2002-2013 was performed. Ten AMLwvf were compared to 77 RCC; 33 clear cell (cc), 35 papillary (p), 9 chromophobe (ch). A blinded radiologist measured T2W signal-intensity ratio (SIR), chemical-shift (CS) SI-index and area under CE-MRI curve (CE-AUC). Regression modeling and ROC analysis was performed. RESULTS T2W-SIR was lower in AMLwvf (0.64 ± 0.12) compared to cc-RCC (1.37 ± 0.30, p < 0.001), ch-RCC (0.94 ± 0.19, p = 0.005) but not p-RCC (0.74 ± 0.17, p = 0.2). CS-SI index was higher in AMLwvf (16.1 ± 31.5 %) compared to p-RCC (-5.2 ± 26.1 %, p = 0.02) but not ch-RCC (3.0 ± 12.5 %, p = 0.1) or cc-RCC (7.7 ± 17.9 %,p = 0.1). CE-AUC was higher in AMLwvf (515.7 ± 144.7) compared to p-RCC (154.5 ± 92.8, p < 0.001) but not ch-RCC (341.5 ± 202.7, p = 0.07) or cc-RCC (520.9 ± 276.9, p = 0.95). Univariate ROC-AUC were: T2SIR = 0.86 (CI 0.77-0.96); CE-AUC = 0.76 (CI 0.65-0.87); CS-SI index = 0.66 (CI 0.4.3-0.85). Logistic regression models improved ROC-AUC, A) T2 SIR + CE-AUC = 0.97 (CI 0.93-1.0) and T2 SIR + CS-SI index = 0.92 (CI 0.84-0.99) compared to univariate analyses (p < 0.05). The optimal sensitivity/specificity of T2SIR + CE-AUC and T2SIR + CS-SI index were 100/88.8 % and 60/97.4 %. CONCLUSION MRI, using multi-variate modelling, is accurate for diagnosis of AMLwvf. KEY POINTS • AMLwvf are difficult to prospectively diagnose with imaging. • MRI findings associated with AMLwvf overlap with various RCC subtypes. • T2W-SI combined with chemical-shift SI-index is specific for AMLwvf but lacks sensitivity. • T2W-SI combined with AUC CE-MRI is sensitive and specific for AMLwvf. • Models incorporating two or more findings are more accurate than univariate analysis.
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Affiliation(s)
- Nicola Schieda
- Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9.
| | - Marc Dilauro
- Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - Bardia Moosavi
- Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - Taryn Hodgdon
- Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - Gregory O Cron
- Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - Matthew D F McInnes
- Department of Medical Imaging, The Ottawa Hospital, 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - Trevor A Flood
- Department of Anatomical Pathology, The Ottawa Hospital, The University of Ottawa, 501 Smyth Road, 4th floor CCW, Room 4278, Ottawa, Ontario, Canada, K1Y 4E9
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Andersen PE, Thorlund MG, Wennevik GE, Pedersen RL, Lund L. Interventional treatment of renal angiomyolipoma: immediate results and clinical and radiological follow-up of 4.5 years. Acta Radiol Open 2015; 4:2058460115592442. [PMID: 26346549 PMCID: PMC4548745 DOI: 10.1177/2058460115592442] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 05/21/2015] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Renal angiomyolipoma is rare, but many of these patients may have an acute debut with severe bleeding. These patients need urgent treatment with interventional embolization as an attractive option. PURPOSE To investigate the technical and clinical effect of this treatment and to evaluate long-term clinical outcomes with clinical control and radiological imaging. MATERIAL AND METHODS Eight patients with angiomyolipoma were treated with embolization. Five patients were treated acutely. Five patients were followed-up for mean 4.5 years with clinical and radiological examinations. RESULTS The renal angiomyolipoma decreased significantly from mean 7.2 cm to 2.9 cm after embolization (p = 0.04). Cortical infarctions of about one-third of the circumference of the embolized kidneys could be detected on follow-up examinations, but all patients had normal total kidney function. The bleeding was primarily stopped in all patients, however, in one patient bleeding from a lumbar artery was supplementary embolized within 24 h. In another case the interventional procedure ended up in embolization of the whole kidney as it was impossible to embolize all the feeding arteries selectively. One patient had a nephrectomy one month after embolization because of infection and re-bleeding and one patient after 2.5 years because of tumor size >4 cm. The technical success was 7/8 (88%) and clinical success was 6/8 patients (75%). CONCLUSION Selective embolization of renal angiomyolipoma is a minimally invasive and safe procedure with few complications. It is a nephron sparing alternative to renal resection. The reduction in tumor size after embolization is significant and long-lasting.
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Affiliation(s)
| | | | | | | | - Lars Lund
- Odense University Hospital, Odense C, Denmark
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21
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Tuberous Sclerosis Complex: State-of-the-Art Review with a Focus on Pulmonary Involvement. Lung 2015; 193:619-27. [DOI: 10.1007/s00408-015-9750-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2015] [Accepted: 06/15/2015] [Indexed: 12/19/2022]
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22
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Angiomyolipoma (AML) without visible fat: Ultrasound, CT and MR imaging features with pathological correlation. Eur Radiol 2015; 26:592-600. [PMID: 26032880 DOI: 10.1007/s00330-015-3851-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 04/25/2015] [Accepted: 05/13/2015] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To compare imaging findings with histopathology in AML without visible fat (AMLwvf). MATERIAL AND METHODS With IRB approval, we identified 18 AMLwvf that underwent CT between 2002-2014. A radiologist measured NECT-attenuation, corticomedullary (CM) and nephrographic (NG) enhancement, echogenicity relative to renal cortex (RC) (N = 5), T2W (T2AML/T2RC) signal-intensity (SI), and chemical-shift SI ([SIIN-PHASE - SIOPPOSED-PHASE]/SIIN-PHASE) indices (N = 6). A pathologist re-evaluated 15/18 AMLwvf for 1) < or > 25% adipocytes/high-power-field (HPF), 2) "many or few" blood vessels. Comparisons were performed using chi-square and independent t-tests. RESULTS 73.3%(11/15) of AMLwvf had <25% adipocytes/HPF and 86.7%(13/15) had "many" blood vessels. NECT-attenuation was 41.8(±6.9) HU. 61.1 %(11/18) of AMLwvf were hyper-attenuating and 38.9%(7/18) iso-attenuating; attenuation was associated with %-adipocytes/HPF, (p = 0.01). CM/NG enhancement were 63.3(±20.8)/51.7(±15.5) HU. 72.2%(13/18) of AMLwvf had wash-out enhancement, with no association with amount of blood vessels at pathology, (p = 0.68). No difference in echogenicity was noted by histology (p > 0.05). All AMLwvf were T2-hypointense (SI ratio = 0.61 [±0.1]). 2/6 AMLwvf showed SI drop on chemical-shift MRI; both were iso-attenuating and were associated with >25% adipocytes/HPF (p = 0.04). CONCLUSIONS AMLwvf are typically T2-hypointense and hyper-attenuating with wash-out enhancement due to abundant smooth muscle and vessels respectively. Iso-attenuating AMLwvf with microscopic fat on MRI contain more adipocytes/HPF. KEY POINTS • Five percent of AML do not demonstrate detectable fat on imaging • These AML are hyperattenuating and T2-hypointense due to abundant smooth muscle • These AML show washout enhancement without association to vessel count at histopathology • Iso-attenuating AML with microscopic fat on MRI show >25% adipocytes/HPF • The term "AML without visible fat" is proposed to reduce ambiguity.
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Hodgdon T, McInnes MDF, Schieda N, Flood TA, Lamb L, Thornhill RE. Can Quantitative CT Texture Analysis be Used to Differentiate Fat-poor Renal Angiomyolipoma from Renal Cell Carcinoma on Unenhanced CT Images? Radiology 2015; 276:787-96. [PMID: 25906183 DOI: 10.1148/radiol.2015142215] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE To determine the accuracy of texture analysis to differentiate fat-poor angiomyolipoma (fp-AML) from renal cell carcinoma (RCC) on unenhanced computed tomography (CT) images. MATERIALS AND METHODS In this institutional review board-approved retrospective case-control study, patients with AML and RCC were identified from the pathology database: there were 16 patients with fp-AML (no visible fat at unenhanced CT) and 84 patients with RCC. Axial unenhanced CT images were contoured manually by two independent analysts. Texture analysis was performed for each lesion, and reproducibility was assessed. Texture features related to the gray-level histogram, gray-level co-occurrence, and run-length matrix statistics were evaluated. The most discriminative features were used to generate support vector machine (SVM) classifiers. Diagnostic accuracy of textural features was assessed and 10-fold cross validation was performed. Unenhanced CT images for each patient were independently reviewed by two blinded radiologists who subjectively graded lesion heterogeneity on a five-point scale. Differences in area under the receiver operating characteristic curve (AUC) between subjective heterogeneity ratings and textural features were evaluated by using the DeLong method. RESULTS There was lower lesion homogeneity and higher lesion entropy in RCCs (P ≤ .01). A model incorporating several texture features resulted in an AUC of 0.89 ± 0.04. The average SVM accuracy of textural features ranged from 83% to 91% (after 10-fold cross validation). An optimal subjective heterogeneity rating of 2 or higher was identified as a predictor of RCC for both readers, with no significant difference in AUC between readers (P = .06). Each of the three textural-based classifiers was more accurate than either radiologists' subjective heterogeneity ratings for the models incorporating a subset of the top three textural features (difference in AUC between textural features and subjective visual heterogeneity, 0.25; 95% confidence interval: 0.02, 0.47; P = .03). CONCLUSION CT texture analysis can be used to accurately differentiate fp-AML from RCC on unenhanced CT images.
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Affiliation(s)
- Taryn Hodgdon
- From the Departments of Radiology (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada K1H 8M5; Departments of Medical Imaging (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), The Ottawa Hospital, Ottawa, Ontario, Canada; and Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (M.D.F.M., N.S., R.E.T.)
| | - Matthew D F McInnes
- From the Departments of Radiology (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada K1H 8M5; Departments of Medical Imaging (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), The Ottawa Hospital, Ottawa, Ontario, Canada; and Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (M.D.F.M., N.S., R.E.T.)
| | - Nicola Schieda
- From the Departments of Radiology (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada K1H 8M5; Departments of Medical Imaging (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), The Ottawa Hospital, Ottawa, Ontario, Canada; and Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (M.D.F.M., N.S., R.E.T.)
| | - Trevor A Flood
- From the Departments of Radiology (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada K1H 8M5; Departments of Medical Imaging (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), The Ottawa Hospital, Ottawa, Ontario, Canada; and Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (M.D.F.M., N.S., R.E.T.)
| | - Leslie Lamb
- From the Departments of Radiology (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada K1H 8M5; Departments of Medical Imaging (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), The Ottawa Hospital, Ottawa, Ontario, Canada; and Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (M.D.F.M., N.S., R.E.T.)
| | - Rebecca E Thornhill
- From the Departments of Radiology (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), University of Ottawa, 451 Smyth Rd, Ottawa, ON, Canada K1H 8M5; Departments of Medical Imaging (T.H., M.D.F.M., N.S., L.L., R.E.T.) and Anatomical Pathology (T.A.F.), The Ottawa Hospital, Ottawa, Ontario, Canada; and Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada (M.D.F.M., N.S., R.E.T.)
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Intracellular lipid in papillary renal cell carcinoma (pRCC): T2 weighted (T2W) MRI and pathologic correlation. Eur Radiol 2015; 25:2134-42. [DOI: 10.1007/s00330-015-3610-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 01/04/2015] [Accepted: 01/16/2015] [Indexed: 12/23/2022]
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Ramamurthy NK, Moosavi B, McInnes MDF, Flood TA, Schieda N. Multiparametric MRI of solid renal masses: pearls and pitfalls. Clin Radiol 2014; 70:304-16. [PMID: 25472466 DOI: 10.1016/j.crad.2014.10.006] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 10/04/2014] [Accepted: 10/08/2014] [Indexed: 12/17/2022]
Abstract
Functional imaging [diffusion-weighted imaging (DWI) and dynamic contrast enhancement (DCE)] techniques combined with T2-weighted (T2W) and chemical-shift imaging (CSI), with or without urography, constitutes a comprehensive multiparametric (MP) MRI protocol of the kidneys. MP-MRI of the kidneys can be performed in a time-efficient manner. Breath-hold sequences and parallel imaging should be used to reduce examination time and improve image quality. Increased T2 signal intensity (SI) in a solid renal nodule is specific for renal cell carcinoma (RCC); whereas, low T2 SI can be seen in RCC, angiomyolipoma (AML), and haemorrhagic cysts. Low b-value DWI can replace conventional fat-suppressed T2W. DWI can be performed free-breathing (FB) with two b-values to reduce acquisition time without compromising imaging quality. RCC demonstrates restricted diffusion; however, restricted diffusion is commonly seen in AML and in chronic haemorrhage. CSI must be performed using the correct echo combination at 3 T or T2* effects can mimic intra-lesional fat. Two-dimensional (2D)-CSI has better image quality compared to three-dimensional (3D)-CSI, but volume averaging in small lesions can simulate intra-lesional fat using 2D techniques. SI decrease on CSI is present in both AML and clear cell RCC. Verification of internal enhancement with MRI can be challenging and is improved with image subtraction. Subtraction imaging is prone to errors related to spatial misregistration, which is ameliorated with expiratory phase imaging. SI ratios can be used to confirm subtle internal enhancement and enhancement curves are predictive of RCC subtype. MR urography using conventional extracellular gadolinium must account for T2* effects; however, gadoxetic acid enhanced urography is an alternative. The purpose of this review it to highlight important technical and interpretive pearls and pitfalls encountered with MP-MRI of solid renal masses.
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Affiliation(s)
- N K Ramamurthy
- Department of Radiology, The Ottawa Hospital, The University of Ottawa, Civic Campus C1 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - B Moosavi
- Department of Radiology, The Ottawa Hospital, The University of Ottawa, Civic Campus C1 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - M D F McInnes
- Department of Radiology, The Ottawa Hospital, The University of Ottawa, Civic Campus C1 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9
| | - T A Flood
- Division of Anatomical Pathology, The Ottawa Hospital, The University of Ottawa, 501 Smyth Road, 4th Floor CCW, Room 4278, Ottawa, Ontario, Canada, K1Y 4E9
| | - N Schieda
- Department of Radiology, The Ottawa Hospital, The University of Ottawa, Civic Campus C1 1053 Carling Avenue, Ottawa, Ontario, Canada, K1Y 4E9.
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Schieda N, Kielar AZ, Al Dandan O, McInnes MDF, Flood TA. Ten uncommon and unusual variants of renal angiomyolipoma (AML): radiologic-pathologic correlation. Clin Radiol 2014; 70:206-20. [PMID: 25468637 DOI: 10.1016/j.crad.2014.10.001] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 09/26/2014] [Accepted: 10/06/2014] [Indexed: 12/22/2022]
Abstract
Classic (triphasic) renal angiomyolipoma (AML) is currently classified as a neoplasm of perivascular epithelioid cells. For diagnosis of AML, the use of thin-section non-contrast enhanced CT (NECT) improves diagnostic accuracy; however, identifying gross fat within a very small AML is challenging and often better performed with chemical-shift MRI. Although the presence of gross intra-tumoural fat is essentially diagnostic of AML; co-existing intra-tumoural fat and calcification may represent renal cell carcinoma (RCC). Differentiating AML from retroperitoneal sarcoma can be difficult when AML is large; the feeding vessel and claw signs are suggestive imaging findings. AML can haemorrhage, with intra-tumoural aneurysm size >5 mm a more specific predictor of future haemorrhage than tumor size >4 cm. Diagnosis of AML in the setting of acute haemorrhage is complex; comparison studies or follow-up imaging may be required. Not all AML contain gross fat and imaging features of AML without visible fat overlap with RCC; however, homogeneity, hyperdensity at NECT, low T2-weighted signal intensity and, microscopic fat are suggestive features. Patients with tuberous sclerosis often demonstrate a combination of classic and minimal fat AML, but are also at a slightly increased risk for RCC and should be imaged cautiously. Several rare pathological variants of AML exist including AML with epithelial cysts and epithelioid AML, which have distinct imaging characteristics. Classic AML, although benign, can be locally invasive and the rare epithelioid AML can be frankly malignant. The purpose of this review is to highlight the imaging manifestations of 10 uncommon and unusual variants of AML using pathological correlation.
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Affiliation(s)
- N Schieda
- Department of Radiology, The Ottawa Hospital, The University of Ottawa, Civic Campus C1 1053 Carling Avenue, Ottawa, Ontario K1Y 4E9, Canada.
| | - A Z Kielar
- Department of Radiology, The Ottawa Hospital, The University of Ottawa, Civic Campus C1 1053 Carling Avenue, Ottawa, Ontario K1Y 4E9, Canada
| | - O Al Dandan
- Department of Radiology, King Fahad Hospital, University of Dammam, Al Aqrabiyah, Al Khobar 31952, Saudi Arabia
| | - M D F McInnes
- Department of Radiology, The Ottawa Hospital, The University of Ottawa, Civic Campus C1 1053 Carling Avenue, Ottawa, Ontario K1Y 4E9, Canada
| | - T A Flood
- Division of Anatomical Pathology, The Ottawa Hospital, The University of Ottawa, 501 Smyth Road, 4th Floor CCW, Room 4278, Ottawa, Ontario K1Y 4E9, Canada
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