Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Subscribe Contacts Login 
  Home Print this page Email this page Small font sizeDefault font sizeIncrease font size Users Online: 147  

   Table of Contents      
Year : 2017  |  Volume : 16  |  Issue : 4  |  Page : 311-313

The utility of 99mTechnetium-mercaptoacetyltriglycine renogram in assessing the baseline renal function of a rare incidental ectopic thoracic kidney

Department of Nuclear Medicine, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, CB2 0QQ, UK

Date of Web Publication22-Sep-2017

Correspondence Address:
Ziauddin Saad
Department of Nuclear Medicine, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, CB2 0QQ
Login to access the Email id

DOI: 10.4103/1450-1147.215488

PMID: 29033680

Rights and Permissions

Ectopic thoracic kidney is an extremely rare condition caused by the abnormal location of one or both kidneys in the thoracic cavity. They are usually discovered incidentally on routine imaging. Although commonly asymptomatic, thoracic kidneys are at a risk of malrotation, pelviureteric junction obstruction, and subsequent obstructive nephropathy, by virtue of their long pedicle. We present a case report of an incidental thoracic kidney, for which a 99mtechnetium-mercaptoacetyltriglycine (99mTc-MAG3) renogram was performed to assess the baseline renal function. Although few reports are published in the literature using 99mTc-MAG3 renogram for this indication, we demonstrate a safe and feasible study to establish a baseline assessment of renal function in this group of patients.

Keywords: 99mtechnetium-mercaptoacetyltriglycine renogram, ectopic kidney, renal ectopia, thoracic kidney

How to cite this article:
Zhang TT, Oparandu A, Saad Z. The utility of 99mTechnetium-mercaptoacetyltriglycine renogram in assessing the baseline renal function of a rare incidental ectopic thoracic kidney. World J Nucl Med 2017;16:311-3

How to cite this URL:
Zhang TT, Oparandu A, Saad Z. The utility of 99mTechnetium-mercaptoacetyltriglycine renogram in assessing the baseline renal function of a rare incidental ectopic thoracic kidney. World J Nucl Med [serial online] 2017 [cited 2021 Jan 24];16:311-3. Available from: http://www.wjnm.org/text.asp?2017/16/4/311/215488

   Introduction Top

Renal ectopia is a developmental anomaly characterized by the abnormal location of one or both kidneys. The rarest of these is a thoracic kidney with an incidence of <1 in 10,000, accounting for <5% of all renal ectopias.[1] Thoracic kidneys are discovered incidentally on routine imaging such as ultrasound, intravenous pyelography, intravenous urography, and on computed tomography (CT). This case report highlights the utility of 99mtechnetium-mercaptoacetyltriglycine (99mTc-MAG3) renogram in the baseline assessment of a rare ectopic kidney, incidentally identified on conventional radiography.

   Case Report Top

A previously fit and well 6-month-old boy presented with a history of cough for 6 weeks and underwent a chest radiograph [Figure 1]. This revealed a well-defined intrathoracic mass, abutting the left hemidiaphragm. Subsequently, a CT study was arranged to further characterize the finding [Figure 2]. This revealed a kidney within the posterior mediastinum, above a normal left hemidiaphragm. Detailed past medical history revealed normal physiological and age-specific milestones, with no developmental anomalies. Therefore, the patient was referred to our Nuclear Medicine Department for a 99mTc-MAG3 study to assess the renal function and handling of tracer in the ectopic kidney.
Figure 1: Chest radiograph demonstrating an ovoid mass in the left hemithorax, abutting the left hemidiaphragm

Click here to view
Figure 2: Sagittal reconstruction of computed tomography thorax demonstrates an intrathoracic kidney

Click here to view

After weight measurements, 21MBq of 99mTc-MAG-3 and 8.2 mg of furosemide were administered through a cannula at the start of dynamic imaging (time-0). Dynamic image acquisition was undertaken at a rate of 20 s per frame for 30 min (90 frames in total). The data were analyzed using the GE Discovery Xeleris view 3 functional imaging workstation software (Medical systems Milwaukee, Wisconsin, 2000).

   Results Top

The 99mTc-MAG3 study demonstrated an ectopically placed left kidney in the left hemithorax with the right kidney located in the normal anatomical position [Figure 3]. Both kidneys demonstrated good perfusion, adequate tracer uptake, and rapid transit of activity to the pelvicalyceal systems. The excretory pattern (under furosemide flow rates; time-0) was observed to be brisk, with no evidence of hold up or obstruction. The differential function was found to be essentially within the normal range, with the left kidney at 44% and the right kidney at 56%.
Figure 3:99mtechnetium-mercaptoacetyltriglycine renogram shows the ectopic intrathoracic location of the left kidney. Both kidneys demonstrate a good tracer uptake, rapid transit of activity to the pelvicalyceal system, and unobstructed clearance of tracer

Click here to view

   Discussion Top

Renal embryogenesis involves cranial migration of kidneys from the pelvis to its normal retroperitoneal anatomical location. This embryonic process can be arrested at any point along its path resulting in renal ectopia, usually inferior to its normal position. On rare occasion, the kidney can ascend to a higher location, resulting in a thoracic kidney. The exact mechanism of this is still unclear. However, it has been postulated that delayed closure of the pleuroperitoneal membrane may allow excessive renal ascent.[2] Alternatively, delayed differentiation of the metanephrogenic tissue may cause the renal ascent to be prolonged.[1]

Most ectopic thoracic kidneys are separated from the pleural cavity by a thin layer of pleura,[3] with the renal vasculature and ureters forming a long pedicle which exits through the foramen of Bochdalek. This can predispose to malrotation, with subsequent pelviureteric junction obstruction, obstructive nephropathy, and eventual renal scarring. However, the majority of ectopic kidneys remain asymptomatic.

The choice of radiopharmaceuticals used in assessing renal function varies between departments. In the past three decades, there has been a shift in preference toward 99mTc-MAG3 due to its better target-to-background scintigraphic imaging properties, especially in patients in whom renal failure is anticipated.99m Tc-diethylenetriaminepentaacetic acid (DTPA), on the other hand, is still the radiopharmaceutical choice for departments utilizing its ability to measure the glomerular filtration rate.99m Tc-dimercaptosuccinic acid (DMSA) is preferred when the clinical question pertains to renal scarring, absolute divided renal function, or the detection of functioning renal parenchyma at native or ectopic sites. To date, there are few case reports in the literature utilizing 99mTc-MAG3, 99mTc-DTPA, and 99mTc-DMSA[4],[5] in this rare group of patients. We demonstrate that 99mTc-MAG3 renogram is a safe and feasible study to establish a baseline functional renal assessment in terms of comprehensive radiotracer handling in ectopic thoracic kidneys and to confirm various potential drainage patterns.[6]

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Donat SM, Donat PE. Intrathoracic kidney: A case report with a review of the world literature. J Urol 1988;140:131-3.  Back to cited text no. 1
Yalcinbas YK, Sasmaz H, Canbaz S. Thoracic left kidney: A differential diagnosis dilemma for thoracic surgeons. Ann Thorac Surg 2001;72:281-3.  Back to cited text no. 2
Panossian DH, Thomas RD, Anholm JD. Asymptomatic mediastinal mass in an elderly man. Chest 1995;107:1165-6.  Back to cited text no. 3
Aydin HI, Sarici SU, Alpay F, Gökçay E. Thoracic ectopic kidney in a child: A case report. Turk J Pediatr 2000;42:253-5.  Back to cited text no. 4
Padma S, Pande SR, Sundaram PS. (99m) Tc DTPA renogram indentifies Bochdalek hernia with an intra thoracic kidney as its content. World J Nucl Med 2014;13:193-6.  Back to cited text no. 5
[PUBMED]  [Full text]  
Toba M, Fukuchi K, Hayashida K, Takeda Y, Fukushima K. Intrathoracic mass simulated by ectopic kidney. Clin Nucl Med 2000;25:289-90.  Back to cited text no. 6


  [Figure 1], [Figure 2], [Figure 3]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

  In this article
   Case Report
    Article Figures

 Article Access Statistics
    PDF Downloaded158    
    Comments [Add]    

Recommend this journal