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 Table of Contents  
REVIEW ARTICLE
Year : 2018  |  Volume : 16  |  Issue : 4  |  Page : 148-154

Role of nuclear medicine in evaluation of renal system


Department of Nuclear Medicine, Christian Medical College, Vellore, Tamil Nadu, India

Date of Web Publication16-Apr-2019

Correspondence Address:
Julie Hephzibah
Department of Nuclear Medicine, Christian Medical College, Vellore - 632 004, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/cmi.cmi_51_18

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  Abstract 

The aim of this article is to highlight the importance of Nuclear Medicine imaging in the diagnosis and management of common renal conditions. Nuclear Medicine procedures provide useful information on renal blood flow and individual kidney functions and drainage. The advantages of these procedures are that there is low radiation burden, no sedation or no special pre-procedural preparations are required and are easy to perform and interpret. It is a valuable asset in the imaging of renal system in both adults and children. Renal radiopharmaceuticals are categorized by their uptake and clearance mechanisms for studying glomerular filtration, tubular secretion, or cortical binding.

Keywords: Renography, renovascular hypertension, scintigram


How to cite this article:
Hephzibah J. Role of nuclear medicine in evaluation of renal system. Curr Med Issues 2018;16:148-54

How to cite this URL:
Hephzibah J. Role of nuclear medicine in evaluation of renal system. Curr Med Issues [serial online] 2018 [cited 2019 Aug 26];16:148-54. Available from: http://www.cmijournal.org/text.asp?2018/16/4/148/256319


  Introduction Top


Nuclear scintigraphy provides useful information on renal blood flow and individual kidney functions and drainage. The advantages of Nuclear Medicine Imaging procedures are that there is low radiation burden, no sedation or no special pre-procedural preparations are required and are easy to perform and interpret, and hence, it is a valuable asset in the imaging of renal system in both adults and children.

Renal radiopharmaceuticals are categorized by their uptake and clearance mechanisms for studying glomerular filtration, tubular secretion, or cortical binding.


  Terminologies Top


  • Renogram/renography: Time–activity curve was derived historically from renal probe (nonimaging) or in the current practice from computer-processed dynamic renal imaging studies after drawing region of interest (ROI)
  • Renal scan/scintigram: Images were acquired using radiopharmaceuticals that fix to the cortex and timed sequential images acquired of radiotracer uptake and clearance in the dynamic renal study
  • Differential/individual renal function: Percentage of the right/left renal cortical uptake or retention as a percentage of total renal uptakes was derived from renal scintigraphy
  • Quantitative glomerular filtration rate (GFR)/effective renal plasma flow (ERPF): Clearance (ml/min) was derived from either blood sampling of radiotracer or computer-derived quantitative estimates of renal cortical uptake from scintigraphy.



  Clinical Indications for Radionuclide Scintigraphy Top


  • Perfusion abnormalities
  • Acute/chronic renal failure
  • Renal transplant: Rejection, obstruction, and status of anastomosis
  • Renal trauma or surgical complications
  • Renovascular hypertension/renal artery stenosis (RAS)
  • Quantification of renal function: GFR/ERPF
  • Pyelonephritis
  • Mass versus column of Bertin
  • Ureteral obstruction
  • Vesicoureteral reflux (VUR)
  • Congenital anomalies.



  Radiotracers in Renal Scintigraphy Top


Renal radiopharmaceuticals can be divided into four groups:

  • To estimate renal plasma flow
  • To measure GFR
  • To estimate “functional renal mass” by tubular fixation in the parenchyma
  • To diagnose infectious or malignant lesions.


The other tracers that are available and not in wide applications are given below:

  1. Hydroxyacetyltriglycine (HAG3)


    • Slightly higher urinary extraction
    • Faster renal transit
    • Lower hepatobiliary uptake than mercaptoacetyltriglycine (MAG3)
    • Clearance of HAG3 in humans has been shown to be 72% of that of orthoiodohippurate (OIH).


  2. N-mercaptoacetylglycine


    • Properties similar to those of dimercaptosuccinic acid (DMSA) reaching renal activity plateau more rapidly than DMSA [Table 1] and [Table 2]
    Table 1: Mechanism of uptake and the radiopharmaceutical

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    Table 2: What type of radiopharmaceutical should one ask for various assessments

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  3. Organic cations labeled with Tc99m: No clinical experience has been reported to date, for example:


    • DACH – Diaminocyclohexane
    • Cyclam.


  4. Positron emission tomography radiopharmaceuticals[1]


    1. For imaging renal blood flow


    2. i. 15O-water, 82Rb, 13zN-ammonia, 64Cu-PTSM, 62Cu-PTSM, and 64Cu-ETS.

    3. Renal blood volume


    4. i. Radiolabeled carbon monoxide [15O] CO.

    5. Metabolism


    6. i. Carbon-11-labeled acetate

      ii. 18F-fluoroacetate.

    7. Receptor


    8. i. [11C] MK-996 and [11C] L-159,884

      ii.Radiolabeled angiotensin converting enzyme (ACE) inhibitors: 18F-Fluorocaptopril and11 C-zofenoprilat.



  Cortical Study Top


Technetium-99m DMSA agent of choice for renal parenchymal imaging due to its high cortical accumulation and high sensitivity.

It concentrates predominantly in the proximal convoluted tubules for adequately a long time, thus enabling a comprehensive scintigraphic evaluation. About 90% of Tc-99m DMSA is plasma protein, and hence, glomerular filtration is restricted. The main disadvantage is its relatively more radiation dose in comparison with other renal agents because of tubular fixation of DMSA and hence the longer duration in the renal cortex. However, in practice, Tc-99m DMSA is a remarkable renal parenchymal imaging agent, wherein 50% of the dose administered is located in the kidneys at 1-h injection [Figure 1].
Figure 1: (a) Normal cortical study with homogeneous distribution in both the kidneys. (b) Left contracted kidney with photopenic areas suggestive of renal scars. (c) Bilateral renal scars. (d) Left kidney parenchymal dysfunction with bilateral vesicoureteral reflux, note the dilated and tortuous ureters (Image Courtesy: Nuclear Medicine, CMC Vellore).

Click here to view


Tc-99m DMSA scintigraphy is significantly more sensitive than intravenous urography and ultrasonography and even color Doppler in the detection of renal parenchymal diseases.[2],[3]

Sensitivity for detection of parenchymal defects secondary to infection is from 80% to 100%, but acute pyelonephritis cannot be differentiated from renal scars.[4],[5]

Technetium-99m ethylene dicysteine (EC) scintigraphy gives almost the same details on relative renal function of each kidney as Tc-99m DMSA scintigraphy. In addition, it also gives more information of the perfusion, excretion pattern, and collecting system.

In 52%–78% of children during acute pyelonephritis, abnormal findings on cortical scintigraphy are found and risk of renal scarring can reach 60%.[6] The positive predictive value was raised from 62% to 85% in a semi-quantitative analysis of 99mTc-DMSA for detection of the development of renal scars in children at a high risk.[7]


  Renogram and Diuretic Renography Top


Tubular tracers such as 99mTc-MAG3, EC, and 123I-OIH are commonly preferred to the glomerular agent 99mTc-Diethylenetriaminepentaacetic acid (DTPA) due to their higher renal extraction ratio and rapid plasma clearance, particularly in infants and young children and also in patients with renal impairment. Bearing in mind the immaturity of nephrons in newborns, the standard recommendation is that diuretic renography should be delayed until 4 weeks of age as renal tubules will not be responding to the effect of furosemide. Renal function maturation gradually occurs in the first 2 years of life. In India, only EC is available and hence widely used [Table 4].
Table 4: Diagnostic criteria: (Consens. Report JNM '96:1876, Semin NM 4/99:128-145)

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Renogram phase

  • I – Vascular phase (flow study): Aorta to kidney ~3"
  • II – Parenchymal phase (kidney to background): Tpeak <5' (MAG3) and 2–3' (EC), 3–4' (DTPA)
  • III – Washout (excretory) phase.


The guidelines published by the Society of Nuclear Medicine and the European Nuclear Medicine Association recommend the use of furosemide at a dose of 1 mg/kg, up to a maximum of 40 mg.[8]

To inject furosemide at the same time, i.e. F0 as the radiopharmaceutical is a recent proposal. It has gained much acceptance, especially in children, as it avoids repeated punctures during injection and reduces the study time.[9],[10] Simultaneous injection of radiotracer and furosemide does not interfere with the study of renal function. The diuretic effect begins 1–2 min postinjection of the diuretic, and parenchymal extraction of tubular tracers occurs in the 1st min after bolus injection, with a normal time to peak of usually <3 min.

Diuretic response is evaluated by visual and quantitative interpretation of the dynamic acquisition. Postvoid images are a must as a full bladder may delay urinary flow even if there is an unobstructed system. The effect a change from the supine position to erect or prone due to gravity is recommended in situ ations of incomplete drainage [Figure 2], [Figure 3], [Figure 4]. The role of bladder catheterization is still under debate usually not recommended in routine practice.
Figure 2: (a) Normal renal scintigraphy with uniform and prompt tracer uptake in both the kidneys and a normal drainage pattern, the bladder is visualized within 4 min. Each frame is acquired for 2 min up to 20 min followed by postvoid and a delayed image after 2 h. (b) The renogram curve shows the tracer clearance of both right kidney (red) and Left kidney (blue) to be prompt with maximum tracer activity within the kidneys between 2 and 3 min and prompt tracer clearance thereafter depicted by the downward slope of the graph (Image Courtesy: Nuclear Medicine, CMC Vellore).

Click here to view
Figure 3: (a) Right pelvic ureteric junction obstruction – The parenchymal uptake is impaired in the right kidney, the pelvicalyceal system is grossly enlarged with no tracer clearance from the collecting system. (b) The renogram curve of the right (red) shows no evidence of tracer clearance indicated by a flat curve. The left kidney (blue) shows good downward slope consistent with patent drainage (Image Courtesy: Nuclear Medicine, CMC Vellore).

Click here to view
Figure 4: (a) Bilateral pelvic ureteric junction obstruction. The parenchymal uptake is impaired in both the kidneys; the pelvicalyceal system is enlarged with no tracer clearance from the collecting system. (b) The bladder is not seen in the initial images up to 10 min. The renogram curve of both the kidneys shows no evidence of tracer clearance indicated by upward slope (Image Courtesy: Nuclear Medicine, CMC Vellore).

Click here to view


Oral hydration (15 ml/kg during the 30 min prior to study) is usually sufficient. Infants will receive their feeds before the test.

Background-corrected time–activity renal curves are applied to assess urinary drainage and to calculate differential renal function [Figure 5].[11] An obstructed system is evaluated by prompt tracer washout, whereas a rising curve is generally indicative of true obstruction.
Figure 5: Grading renogram curves: 0: Normal, 1: Minor abnormalities, Tmax >5 min, 20 min/max >0.3, 2: Markedly delayed excretion rate with a preserved washout phase, 3: Delayed excretion rate without a washout phase (accumulation curve), 4: Renal failure pattern with measurable kidney uptake, 5: Renal failure pattern without measurable kidney uptake(Taylor. et al. JNM Vol. 37; 1996).[11]

Click here to view


In an adequately hydrated patient, the normal time to peak is <3 min with tubular tracers. Differential renal function should accordingly be measured during the extraction phase of the renogram, i.e. during the first 2 min.

Differential renal function (DRF) is the contribution of each kidney to sum of both left and right renal activities, normally ranging from 45% to 55%.[12] A DRF <40% or a decrease of DRF of >5% on successive diuretic renography studies is indicative of renal function deterioration.

Using DRF to assess renal function is also inapt in patients with solitary kidney, bilateral hydronephrosis, urethral valves, or chronic kidney disease and renal failure.


  Radionuclide Cystography Top


Direct radionuclide cystography is an alternative to the micturating cystourethrogram and it delivers a reduced radiation burden [Table 3].[4],[13],[14] The guidelines published by the Society of Nuclear Medicine for radionuclide cystography in children elaborate in detail the procedures in recommending, performing, interpreting, and reporting the results [Figure 6] and [Figure 7].[15]
Table 3: Differences between micturating cystourethrogram, direct radionuclide cystogram, and indirect radionuclide cystogram

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Figure 6: Normal cystogram: The tracer is limited to the bladder with no tracer reflux into the ureters (Image Courtesy: Nuclear Medicine, CMC Vellore).

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Figure 7: (From left to right) Mild reflux (left side), moderate reflux (right side), severe reflux unilateral (left side) and bilateral (Image Courtesy: Nuclear Medicine, CMC Vellore).

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  Other Indications Top


Renovascular hypertension

Patient preparation

  • Off Angiotensin converting enzyme inhibitors (ACEI) and Angiotensin II (ATII) receptor blockers × 3–7 days
  • Off diuretics × 5–7 days
  • No solid food × 4 h
  • Patient well hydrated
  • 10-ml/kg water 30–60 min pre and during test
  • Tablet Captopril 0.5-1mg/Kg given per orally 1 hour prior to imaging
  • Monitor BP
  • Tracer: Tc-99m DTPA
  • Protocol: 1-day versus 2-day test


    • 1-day test: Baseline scan (1–2 mCi) followed by postcaptopril scan (8–10 mCi)
    • 2-day test: Postcaptopril scan, only if abnormal >> baseline.


Image acquisition: Flow and dynamic imaging is for 20-30minutes [Figure 8]. The interpretation of captopril renogram is given in [Table 5].[15]
Figure 8: (a and b) Precaptopril and postcaptopril renogram curve in a patient with right renal artery stenosis – Note the Grade 2 pattern of the curve (Image Courtesy: Nuclear Medicine, CMC Vellore).

Click here to view
Table 5: ACEI renography interpretation (Taylor et al., Consensus group on ACEI Renography JNM: 1996; 37: 1876-1882)

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  Renal Transplant Top


Scintigraphy plays a vital role in identifying the complications postrenal transplant. The indications for nuclear imaging in renal transplant are the following [Figure 9]:
Figure 9: Normal renal transplant scintigraphy: (a) Flow images – Graft is visualized alongside the iliac artery. (b) Renal graft parenchyma visualized well with no background activity and fairly good bladder drainage. (c) Renogram showing a downslope (Image Courtesy: Nuclear Medicine, CMC Vellore).

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  • Early complications


    • Perfusion status in renal arterial or venous thrombosis
    • Acute tubular necrosis (ATN).


  • Late complications


  • Obstruction


    • RAS
    • VUR
    • Urine leak
    • Hematoma.



  Congenital Anomalies Top


Nuclear Medicine imaging is useful in congenital anomalies such as hoseshoe kidney, ectopic and duplex kidneys etc., [Figure 10], [Figure 11], [Figure 12].
Figure 10: Horseshoe kidney: Sometimes, this anomaly is missed in other conventional imaging. The functioning of individual moieties can be determined in the scintigram. An anterior imaging is preferred for precise estimation (Image Courtesy: Nuclear Medicine, CMC Vellore).

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Figure 11: Ectopic kidney: Right ectopic kidney (arrow). Imaging of ectopic kidney is done anteriorly to allow estimation of percentage function (Image Courtesy: Nuclear Medicine, CMC Vellore).

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Figure 12: (a) Duplex kidney (right duplex – arrow). (b) Cross fused kidney (arrow): In deciding about surgery in the pathological moiety the split function will give an idea about the individual renal function (Image Courtesy: Nuclear Medicine, CMC Vellore).

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Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Szabo Z, Xia J, Mathews WB. Radiopharmaceuticals for renal positron emission tomography imaging. Semin Nucl Med 2008;38:20-31.  Back to cited text no. 1
    
2.
Hitzel A, Liard A, Véra P, Manrique A, Ménard JF, Dacher JN, et al. Color and power Doppler sonography versus DMSA scintigraphy in acute pyelonephritis and in prediction of renal scarring. J Nucl Med 2002;43:27-32.  Back to cited text no. 2
    
3.
Stokland E, Hellström M, Jakobsson B, Sixt R. Imaging of renal scarring. Acta Paediatr Suppl 1999;88:13-21.  Back to cited text no. 3
    
4.
Piepsz A, Ham HR. Pediatric applications of renal nuclear medicine. Semin Nucl Med 2006;36:16-35.  Back to cited text no. 4
    
5.
Kovanlikaya A, Okkay N, Cakmakci H, Ozdoǧan O, Degirmenci B, Kavukcu S, et al. Comparison of MRI and renal cortical scintigraphy findings in childhood acute pyelonephritis: Preliminary experience. Eur J Radiol 2004;49:76-80.  Back to cited text no. 5
    
6.
Ilyas M, Mastin ST, Richard GA. Age-related radiological imaging in children with acute pyelonephritis. Pediatr Nephrol 2002;17:30-4.  Back to cited text no. 6
    
7.
Hitzel A, Liard A, Dacher JN, Gardin I, Ménard JF, Manrique A, et al. Quantitative analysis of 99mTc-DMSA during acute pyelonephritis for prediction of long-term renal scarring. J Nucl Med 2004;45:285-9.  Back to cited text no. 7
    
8.
Shulkin BL, Mandell GA, Cooper JA, Leonard JC, Majd M, Parisi MT, et al. Procedure guideline for diuretic renography in children 3.0. J. Nucl Med Technol 2008:36:162-8.  Back to cited text no. 8
    
9.
Boubaker A, Prior J, Antonescu C, Meyrat B, Frey P, Delaloye AB. F10 renography in neonates and infants younger than 6 months: An accurate method to diagnose severe obstructive uropathy. J Nucl Med 2001;42:1780-8.  Back to cited text no. 9
    
10.
Wong JC, Rossleigh MA, Farnsworth RH. Utility of technetium-99m-MAG3 diuretic renography in the neonatal period. J Nucl Med 1995;36:2214-9.  Back to cited text no. 10
    
11.
Taylor A, Nally J, Aurell M, Blaufox D, Dondi M, Dubovsky E, et al. Consensus report on ACE inhibitor renography for detecting renovascular hypertension. Radionuclides in Nephrourology Group. Consensus Group on ACEI Renography. J Nucl Med 1996;37:1876-82.  Back to cited text no. 11
    
12.
Gordon I, Colarinha P, Fettich J, Fischer S, Frökier J, Hahn K, et al. Guidelines for standard and diuretic renography in children. Eur J Nucl Med 2001;28:BP21-30.  Back to cited text no. 12
    
13.
Mandell GA, Eggli DF, Gilday DL, Heyman S, Leonard JC, Miller JH, et al. Procedure guideline for radionuclide cystography in children. Society of nuclear medicine. J Nucl Med 1997;38:1650-4.  Back to cited text no. 13
    
14.
Fettich J, Colarinha P, Fischer S, Frökier J, Gordon I, Hahn K, et al. Guidelines for direct radionuclide cystography in children. Eur J Nucl Med Mol Imaging 2003;30:B39-44.  Back to cited text no. 14
    
15.
Mandell GA, Eggli DF, Gilday DL, Heyman S, Leonard JC, Miller JH, et al. Procedure guideline for radionuclide cystography in children. Society of Nuclear Medicine. J Nucl Med 1997; 38:1650-4.  Back to cited text no. 15
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5]



 

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  In this article
Abstract
Introduction
Terminologies
Clinical Indicat...
Radiotracers in ...
Cortical Study
Renogram and Diu...
Radionuclide Cys...
Other Indications
Renal Transplant
Congenital Anomalies
References
Article Figures
Article Tables

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