|ORIGINAL CONTRIBUTION - CLINICS IN NUCLEAR MEDICINE
|Year : 2016 | Volume
| Issue : 2 | Page : 86-89
Role of dynamic renal scintigraphy with Tc99m DTPA in symptomatic patients with horseshoe kidney
Aditi K Sehgal, Ravinder S Sethi, Padma A Namgyal, Deepa Kumar
Department of Nuclear Medicine, V.M.M.C. and Safdarjung Hospital, New Delhi, India
|Date of Web Publication||30-Dec-2016|
Ravinder S Sethi
Department of Nuclear Medicine, V.M.M.C. and Safdarjung Hospital, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
Objectives: The purpose of this study was to diagnose obstructive hydronephrosis in symptomatic patients of horseshoe kidney with Technetium-99m (Tc-99m) diethylenetriamine pentaacetic acid (DTPA) diuretic renal scintigraphy. Patients and Methods: We retrospectively reviewed 30 symptomatic patients with horseshoe kidney who were referred to our department for Tc99m-DTPA/Tc99m L, L EC scan to look for subrenal drainage pattern from January 2011 to May 2016. Tc99m DTPA scan was done in all 30 patients. Tc99m dimercaptosuccinic acid III (DMSA-III) scan was done in 12 of these patients. Results: 30 symptomatic patients (21 adults and 9 children) with mean age 32.47 yrs and 5.55 years respectively with a known diagnosis of horse shoe kidney on ultrasonography (USG) were analysed with respect to patient symptoms, drainage pattern and consequences of stasis due to renal anomaly. Out of 30 patients (60 renal moieties), 24 were hydronephrotic as reported on USG by a competent radiologist. Out of these 24 moieties, 10 showed obstructed clearance pattern/slow sub-renal drainage and rest were normal. Other outcomes like asymmetrical cortical function, urolithiasis, Urinary tract infection (UTI) and scarring have also been described. Conclusion: DTPA renal scintigraphy is a non-invasive and sensitive investigation for the diagnosis of obstructive hydronephrosis in horseshoe kidney. It can very well be used in very young patients for an early diagnosis and management. Long term follow up would be advisable in these patients especially to monitor development of complications. Its importance along with USG cannot be downplayed as the added advantages like functional information, drainage pattern, differential function are necessary for a justified management protocol.
Keywords: DMSA scan, diuretic renal scintigraphy, Horseshoe Kidney, Technetium-99m diethylenetriamine-pentaacetic acid (Tc99m DTPA), hydronephrosis
|How to cite this article:|
Sehgal AK, Sethi RS, Namgyal PA, Kumar D. Role of dynamic renal scintigraphy with Tc99m DTPA in symptomatic patients with horseshoe kidney. Astrocyte 2016;3:86-9
|How to cite this URL:|
Sehgal AK, Sethi RS, Namgyal PA, Kumar D. Role of dynamic renal scintigraphy with Tc99m DTPA in symptomatic patients with horseshoe kidney. Astrocyte [serial online] 2016 [cited 2019 Aug 23];3:86-9. Available from: http://www.astrocyte.in/text.asp?2016/3/2/86/197212
| Introduction|| |
Horseshoe kidney is the most common kidney anomaly, with an incidence of approximately 1 in 400.  Hydronephrosis, urolithiasis, and infection are the three most common clinical complications of horseshoe kidney.  Stasis of urine is the common etiopathogenetic factor of these complications. There is a high incidence of hydronephrosis in horseshoe kidneys as compared to normal kidneys (65 and 7%, respectively) and 63% of the patients have bilateral involvement. The anomalous structure of the organ is conducive to the obstruction of urinary tracts.  Differentiation between the obstructive and non-obstructive conditions is obviously essential for precise diagnosis and effective therapy. Diuretic renography with 99mTc-diethylene triamine penta acetic acid (99mTc-DTPA) has proved to be a reliable, non-invasive test for the diagnosis of upper urinary tract obstruction. , Dimercaptosuccinic acid (DMSA) cortical scintigraphy is done for differential function and status of the cortical outline of the kidneys. 
| Materials and Methods|| |
Thirty patients (21 adults and 9 children) with age ranging from 12 days to 62 years were referred to our department from pediatrics, internal medicine, urology, pediatric surgery, nephrology, and surgery departments for DTPA scan or DTPA and DMSA scans with various indications such as differential function, glomerular filtration rate, subrenal drainage, and cortical scarring.
For DTPA scan, adequate hydration was ensured. On table, injection of 1-5 mCi of Tc99m DTPA with furosemide injection (1 mg/kg with maximum of 40 mg dose) F = 0 protocol was injected, and dynamic imaging (posterior view) included perfusion phase with 2 s/frame for 1 min, followed by cortical phase 15 s/frame for 24 min. No bladder catherization was done. Pre-void, post-void, and delayed static images were acquired.
Region of interest (ROI) was drawn around the kidneys and background with 4 pixel in all the kidneys and renogram curves were obtained. Clearance half time was calculated (T1/2) and T1/2 of >20 min was classified as slow drainage. Retention in the Pelvicalyceal System for more than 4 h was labelled as pelviureteric junction (PUJ) obstruction.
DMSA was performed after 2 h of intravenous injection of 1-4 mCi of Tc99m DMSA. 500 kcts were acquired in anterior, posterior, and bilateral obliques in 128 × 128 matrix. Differential function was calculated by the geometric mean method with ROI around the kidneys.
Results describe the most common presentation and scan findings in children and adults.
| Results|| |
A total 30 symptomatic patients were analyzed with DTPA renal scintigraphy, and out of these, 12 underwent DMSA cortical scan as well. The results have been divided into two based on the age of patients (≤12 years as children and >12 years as adults). Out of the 30 patients, 21 were adults [Table 1]; 13 were males and 8 females with age ranging from 12 to 62 years. Pain abdomen/flank pain was the most common symptom in more than 80% of the adult patients; dysuria, fever, and dribbling of urine were other symptoms. Six (28.5%) patients showed slow subrenal drainage (T1/2 >20 min) on DTPA scan. Out of these, 5 patients showed slow subrenal drainage and 1 patient (4.7%) showed retention of the tracer in PCS for >4 h and was labeled as PUJ obstruction. Calculi were seen in 10 out of 21 (47.6% patients and urinary tract infection (UTI) was observed in 3 out of 21 (14.28%) patients.
Children were fewer in number (9) [Table 2] in comparison to adults, with 5 males and 4 females, age range being 12 days to 12 years. Pain was the most common symptom for children. Palpable mass in abdomen, crying during micturition, fever, etc., were other common symptoms. Similar consequences were observed in this group with calculi (11%), UTI (11%), and PUJ obstruction (22%) being the more common ones. Drainage pattern with DTPA was correlated with ultrasonography findings for all the 30 patients [Table 3].
|Table 3: Hydronephrosis as Reported on Ultrasonography for 30 Patients (adults and children) and its Correlation with Drainage Pattern on DTPA Scan |
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Twenty eight out of 30 patients had Kidney Function Tests within normal limits. Two adult patients had raised serum creatinine. Out of these 2, 1 patient had adequate drainage from one renal moiety and other moiety being small with slow drainage. The other patient had bilateral hydronephrosis with one non-functioning moiety and other having an impaired function.
| Discussion|| |
Horseshoe kidney is the most common form of kidney fusion anomaly and occurs approximately twice as often in males as in females. In 90% of horseshoe kidney cases, the fusion involves lower poles.  In this study, 18 of the 30 patients were males and 12 were females. In addition, in all the patients, fusion involved the lower poles. The diagnosis of horseshoe kidney is usually an incidental diagnosis. A large prospective study was conducted by Kao et al. to detect obstructive hydronephrosis incidently detected horseshoe kidneys in school children. Although the percentage of obstructive HDN was low, follow-up on DTPA would be valueable for early dection of developing complications.  Horseshoe is a difficult ultrasound diagnosis, especially if the isthmus is not seen.  DMSA renal cortical scintigraphy can delineate the connecting bridge of the renal parenchyma and abnormal axis of the kidneys with the connection poles directed medially. , The fusion is usually anterior to major vessels and the spine, therefore, the posterior view on a DMSA scan is not as good as the anterior view in delineating the fusion portion. Asymmetrical development of the horseshoe kidney, with a difference of greater than 10% relative function, between each kidney was seen in 9 (30%) of our patients.
Shimkus and Mekhanna reported a 64% rate of hydronephrosis and a 63% rate of bilateral involvement in horseshoe kidneys.  All the 30 cases depicted in our study were initially diagnosed on ultrasonography. Out of 30 patients (60 moieties), 24 moieties (40%) had hydronephrosis of different grade. Nine moieties (all adults) out of 24 were mild hydronephrosis, and correlative DTPA showed a near normal drainage pattern. These patient could be let off and put on a long term follow up. 10 moieties (7 adults and 3 children) out of 24 had moderate grade hydronephrosis. On DTPA 5 moieties (3 adults and 2 children) out of these 10 showed non obstructive clearance and rest (4 adults and 1 child) showed slow subrenal drainage (t1/2 >20 minutes). These patients were the most benefitted as operate or not to operate is a big question with such findings. Five moieties showed gross hydronephrosis on ultrasonography, out of which 3 (1 adult and 2 children) depicted classical PUJ obstruction on DTPA, and other 2 (1 adult and 1 child) had poorly functioning kidney with slow subrenal drainage. Additional advantage of DTPA here was information regarding functional status of moieties, postoperative follow-up in some, and routine follow-up for the rest.
Even though the diagnosis of horseshoe kidney in this study was established on ultrasonography in most of the patients, questions such as functional status and role in causing various symptoms were not well answered.
Pitts and Muecke reviewed 170 cases of horseshoe kidney and reported that 21% were affected with urolithiasis, 15% with ureteropelvic junction obstruction, and 31% with pyuria;  in our study, rate of these were as 36, 10, and 13.3%, respectively. Kucera reported that 85% of horseshoe kidneys were hydronephrotic but only some had bilateral HDN.  In our study, HDN was noted in a total of 9 cases and bilateral in just 1 case. However, these studies involved more adult cases than pediatric cases.
Segura et al. reported that more than a third of children with a horseshoe kidney were symptomatic during their first year of life. By the end of the third year, more than half had symptoms that led to clinical visits.  However, in a long term follow-up, Glenn reported that 60% of the patients remained symptom free over a 10-year period.  However, the procedure for diuretic renography in children is not well-standardized, especially as it concerns issues relating to intravenous hydration and bladder catheterization. , In pediatric patients, dynamic renal scans are generally carried out in the supine position, and thus failure to drain may be related to the absence of gravity assisted drainage. Haden et al. emphasized that tracer retention must be demonstrated in the upright position to indicate obstruction.  Wong et al. reported that quantitative, gravity assisted drainage of radioactive urine from the dilated renal pelvis is useful to confirm obstruction in diuretic renography in the investigation of hydronephrosis in children.  In an attempt to exclude some false positive diuretic results, data should be collected following a change in posture and emptying of the bladder.  The supine position in this study may have interfered with the passage of urine through the fusion part of horseshoe kidney and caused transient stasis of urine in the dilated renal pelvis. In this study, an immediate post-void image was obtained in children or in very young children an image was obtained after change in posture.
On a diuretic renogram, the prolonged T1/2 is not only dependent on the presence or absence of obstruction. Poor emptying of the radioactive urine from the renal pelvis can simply be due to a huge volume of the collecting system or renal function impairment . Therefore, surgical operation is not necessarily essential based solely on the prolonged T1/2 in a diuretic renogram. In our study, 9 out of 30 (30%) patients (5 adults and 4 children) had prolonged T1/2. Out of these 9, 3 (10%) patients (1 adult and 2 children) had huge collecting system, and 2 out of 3 subsequently underwent surgical procedure for the same. One patient was followed up on DTPA postoperatively (pyeloplasty), and showed significant improvement in drainage pattern.
| Conclusions|| |
DTPA renal scintigraphy is a non-invasive and sensitive investigation for the diagnosis of obstructive hydronephrosis in horseshoe kidney. It is indispensable in addition to an ultrasound as it gives functional information and conclusive remarks on drainage pattern, which helps in choosing surgical/non-surgical treatment for appropriate patients. It be used in very young patients (our youngest patient was only 12 days old) for an early diagnosis and management. In the present study, we have examined a small cohort of 30 patients who were symptomatic, however, a major number of horseshoe kidneys go undetected as the individuals are commonly asymptomatic. In addition, the number of patients in this study was less, and larger studies with more number of patients will give a clear idea, which will definitely aid in diagnosis and management. Incidence of obstructive hydronephrosis in these patients was 10%. Long-term follow up would be advisable in such patients, especially to monitor the development of complications.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]