CT of renal tumors

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Revision as of 10:39, 2 August 2019 by Mikael Häggström (talk | contribs) (Corrected)
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Author: Mikael Häggström [notes 1]

Planning

Indication for CT urography in hematuria

Most patients with macroscopic hematuria, especially when over 50 years, should undergo both cystoscopy and CT urography.[1]

Microscopic hematuria indicates further workup with cystoscopy and/or CT urography if there are significant underlying risk factors, mainly:[1]

  • Male sex
  • Age, especially being older than 60 years
  • Smoking
  • Pelvic radiation

Other indications and choices of modality

Settings

Selected images from a renal mass specific protocol CT. Corticomedullary phase (axial 7a) demonstrates peripheral enhancement of the renal cortex with minimal opacification of the renal medulla. There is a large renal cell carcinoma in the left kidney which can be differentiated from the normal renal parenchyma by the heterogeneous and differential enhancement. The renal artery and vein are opacified in this phase as well. The collecting system is not opacified (coronal reformat 7b). In the parenchymal phase, the renal cortex and the medulla are enhancing. The renal cell carcinoma in the left kidney is not as well defined when compared to the corticomedullary phase images, but is actually slightly more conspicuous. There is some contrast noted within the collecting system during this phase (7c).[3]

Phases:

  • Initial noncontrast CT, important for detecting calcium or fat in a lesion, and to provide baseline attenuation of any renal masses).[3]
  • Corticomedullary phase, obtained at approximately 70 seconds, with enhancement of the renal cortex as well as the renal vasculature. This phase is valuable in the evaluation of benign renal variants, lymphadenopathy and vasculature, however certain medullary renal masses may not be visible during this phase due to minimal enhancement of the medulla and collecting system.[3]
  • The parenchymal phase, obtained approximately 100-200 seconds after the injection of contrast material. Parenchymal phase imaging demonstrates continued enhancement of the cortex, enhancement of the medulla, and various levels of contrast material in the collecting system. The parenchymal phase is highly important for the detection and characterization of renal masses, parenchymal abnormalities. This method of imaging does not evaluate for abnormalities of the collecting system.[3]

Also, a pyelographic phasecan be acquired 5–15 minutes after contrast administration to evaluate the urothelium of the ureter.[4]

Evaluation

Main parameters of tumors:

  • Size. In case of mixed cystic and solid components, measure the maximal widths of both.
CT scan of a renal angiomyolipoma. It involves the renal cortex, and has an attenuation of less than 20 HU on the Hounsfield scale, which are typical characteristics.[5]
  • Attenuation. An attenuation of less than 20 HU is characteristic of an angiomyolipoma.[5] Renal cell carcinomas and oncocytomas typically demonstrate intense heterogeneous enhancement on the parenchymal phase images and cannot be reliably differentiated from each other. Renal lymphoma on the other hand, will often have decreased enhancement when compared to the renal parenchyma on the parenchymal phase images.[3]
  • Local spread, or staging, which can follow the TNM staging system, where the size and extent of the tumour (T), involvement of lymph nodes (N) and metastases (M) are classified separately. The 1997 revision of the American Joint Committee on Cancer (AJCC) is described below:[6]
Stage I Tumour of a diameter of 7 cm (approx. 2 3⁄4 inches) or smaller, and limited to the kidney. No lymph node involvement or metastases to distant organs.
Stage II Tumour larger than 7.0 cm but still limited to the kidney. No lymph node involvement or metastases to distant organs.
Stage III
any of the following
Tumor of any size with involvement of a nearby lymph node but no metastases to distant organs. Tumour of this stage may be with or without spread to fatty tissue around the kidney, with or without spread into the large veins leading from the kidney to the heart.
Tumour with spread to fatty tissue around the kidney and/or spread into the large veins leading from the kidney to the heart, but without spread to any lymph nodes or other organs.
Stage IV
any of the following
Tumour that has spread directly through the fatty tissue and the fascia ligament-like tissue that surrounds the kidney.
Involvement of more than one lymph node near the kidney
Involvement of any lymph node not near the kidney
Distant metastases, such as in the lungs, bone, or brain.

Report

  • Size
  • Local spread

Most likely type or types of tumor if possible.

Notes

  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Radlines:Authorship for details.

References

  1. 1.0 1.1 USA: Raman, Siva P.; Fishman, Elliot K. (2014). "Bladder Malignancies on CT: The Underrated Role of CT in Diagnosis ". American Journal of Roentgenology 203 (2): 347–354. doi:10.2214/AJR.13.12021. ISSN 0361-803X. 
  2. 2.0 2.1 Bradley, A J; Lim, Y Y (2014). "Imaging of renal masses and staging of renal tumours ". Imaging 23 (1): 20110081. doi:10.1259/img.20110081. ISSN 0965-6812. 
  3. 3.0 3.1 3.2 3.3 3.4 Dongqing Wang (2013). Selected Topics on Computed Tomography . ISBN 9789535111023.  License: CC-BY-3.0. Chapter 1: "Computed Tomography in Abdominal Imaging: How to Gain Maximum Diagnostic Information at the Lowest Radiation Dose" by Kristie Guite, Louis Hinshaw and Fred Lee. DOI: 10.5772/55903
  4. O'Connor, Owen J.; Maher, Michael M. (2010). "CT Urography ". American Journal of Roentgenology 195 (5): W320–W324. doi:10.2214/AJR.10.4198. ISSN 0361-803X. 
  5. 5.0 5.1 Dr Yuranga Weerakkody and Dr Behrang Amini. Renal angiomyolipoma. Radiopaedia. Retrieved on 2019-08-02.
  6. Kidney Cancer / General Information at Weill Cornell Medical College, James Buchanan Brady Foundation, Department of Urology