Comparative Study between some Parameters in Ultrasonography and Renal Scintigraphy in the Evaluation of Hydronephrosis among Iraqi Paediatric patients

 

Rasha Saad Aldoury¹, Ali Yousif Nori², Sarah Ahmed Khalid³

¹Radiology Techniques Department- Al Salam University College.

²Department of Pharmacy, AlMustafa Private University College, Baghdad, Iraq.

³College of Pharmacy, University of Baghdad, Baghdad, Iraq.

 

ABSTRACT:

Hydronephrosis describes a urinary tract abnormality where hydrostatic dilatation of the renal pelvis and calyces exists and considered as a hallmark for obstruction to urine flow downstream. Detecting the pathologic hydronephrosis cases along with the cause using the least invasive techniques is a matter of interest since ages especially in pediatric community. In the Iraqi healthcare practice, many cases are referred for advanced urology imaging tests without clear rational. This study aims to evaluate the rational of referring hydronephrosis pediatric cases to renal scintigraphy studies by comparing the results with the ultrasonography using particular parameters. A cross-sectional observational study involved prospective measurement of a number of variables via two main radiology techniques; sonography and scintigraphy was carried on in Baghdad, Iraq. Classical US and dynamic renal MAG-3 were performed on the same day for each of 35 children aged between 1-5 years presumed or suspected to have obstructive type of hydronephrosis by earlier US work-up. Results revealed a clear statistical significance between normal differential renal function and the good quality of renal drainage of Mag-3 test with the undilated PCS category (p-value 0.028) when measured by our team using the sonography technique. Other results of the calyceal dimension (CD) and the parenchymal thickness (PT) have failed to obtain a statistical significant difference when compared with the categories of the three variables of MAG-3. This study supports the inference of assessing renal function based on sensitive parameters of evolutionary sonography. Each radiologist/nephrologist/urologist should evaluate the measurement of reliable parameters of sonography especially the anteroposterior diameter of the pelvicalyceal system (APD of PCS) at the hilum area and the parenchymal thickness (PT) in millimeters and set the pediatric patient for logical follow-up before recommending the dynamic scintigraphy tests.

 

 

 

INTRODUCTION: 

Imaging studies play an important role in the diagnosis of urinary tract diseases especially among paediatric patients due to its non-invasive ease of access. One of the mostly diagnosed urinary tract conditions in antenatal or postnatal infants is the hydronephrosis^1,2.

 

 

Hydronephrosis describes a urinary tract abnormality where hydrostatic dilatation of the renal pelvis and calyces exists and considered as a hallmark for obstruction to urine flow downstream³. Prenatal hydronephrosis is found in approximately 1-5% of all pregnancies, some of the cases are transient and self-reversible while others are pathologic ones⁴. According to some literature, pelvi ureteric junction (PUJ) obstruction is the most common cause for the condition among children¹. Other widely accepted etiologies are vesicoureteral reflux, ureterovesical junction obstruction, and urethral strictureor stenosis due to involvement of posterior urethral valve. However, more than half of cases share more than one anomaly⁵. When the obstructive-type of hydronephrosis is kept untreated, it may trigger clinical symptoms suchas urinary tract infections, hematuria, impaired renal function, and permanent kidney failure^6,7.

 

On the other hand, the most common cause of hydronephrosis in young adults is the urolithiasis. In older adults, the condition is mostly due to benign prostate hyperplasia (BPH) or intrapelvic neoplasms such as prostate cancer^8,9.

 

Imaging workup involves frequent techniques beyond the first-line test which is the renal ultrasonography to visualize the dilated hydroureteronephrosis. However, detecting the grade (severity) and cause of potential obstruction is not usually sensitive with sonography. Each further type of examination has special advantages and disadvantages resulting in a preoperative multimodality workup.

 

Many methods and techniques are available to diagnose the etiology of hydronephrosis. Among many, ultrasonography is the first-line and has the preliminary picture. However, color doppler can be helpful if a crossing vessel causes the PUJ obstruction. Contrast enhanced ultrasound (US), elastography, and 3D US are a new-techniques introduced to be very helpful in knowing much more details about the urinary tract diseases without risk of radiation^10,11.

 

The fluoroscopy methods are utilized with x-ray-based imaging to visualize the function of the urinary system and can be either antegrade or retrograde pyelography. They involve the intravenous urogram/intravenous urography (IVU), the intravenous pyelography (IVP), and the voiding cystourethrogram/voiding cystourethrography (VCUG) which can be also referred to as the ‘micturation cystourethrography (MCUG). These test studies are useful to exclude the possibility of vesicoureteral reflux or the posterior urethral valve etiologies^12,13,14.

 

The computed tomography (CT) urography is another imaging test that uses ionizing radiationby the aid of a radiopaque contrast agent to evaluate the urinary passages when there is suspicion of renal stones that are not visible in classical x-rays. This, in turn, has the advantage of showing whether there is an obstruction (especially when it is caused by aberrant renal vessel) as well as demonstrating the function of the other kidney when the case is unilateral^15,16. The static and dynamic renal scintigraphy [also called ‘isotope renography’;‘isotope renogram’ or ‘isotope nephrography (ING)’] has been practiced by making the use of a radiotracer (also called radionuclide; radioisotope; nuclear imaging agent; or radiopharmaceutical) to visualize the anatomy and the physiology of the urinary tract. They involve using the metastable nuclear isomer of technetium-99(^99mTc) chelation with mercaptoacetyltriglycine (MAG-3), or diethylenetriaminepentaacetic acid (DTPA), orhipuran or iodine-123 orthoiodohippurate (OlH), or dimercaptosuccinic(DMSA)compounds to identify the causes of stenosis /obstruction of the renal tract and any potential loss of kidney function^17,18.

 

Lastly, the magnetic resonance urography (MRU) imaging technique has been widely introduced as an alternative to the fluoroscopy methods due to its potential for simultaneous visualization of the entire urinary tract and renal parenchyma without exposure to ionizing radiation^19,20.

 

In the Iraqi healthcare practice, many cases are referred for advanced urology imaging tests without clear rational. Internationally, the economic burden and risks of exposure to the radiation or to the contrast agents when there is sub-optimal need is an alarming matter²¹ especially in the developing countries²². Although the renal sonography is sometimes invaluable in detecting causes of hydronephrosis in high sensitivity, ultrasonography is helpful in the clinical decision and timing of referral of cases that really require further functional investigation.

 

This study aims to evaluate the rational of referring hydronephrosis pediatric cases to renal scintigraphy studies by comparing the results with the ultrasonography.

 

MATERIAL AND METHOD:

This cross-sectional observational study involved prospective measurement of a number of variables via two main radiology techniques; sonography and scintigraphy. Classical US and dynamic renal MAG-3were performed on the same day for each of 35 children aged between 1-5 years presumed or suspected to have obstructive type of hydronephrosis by earlier US work-up. The inclusion criteria for case enrolments were having a unilateral significant hydronephrosis diagnosis referred to the radiology clinic for MAG-3 assessment in Baghdad, Iraq.

 

If the case contained information about a previous diagnosis with proper documentation of vesico-ureteral reflux; horse shoe kidney; renal agenesis, posterior urethral valve; or previous renal surgery, it was ruled-out to focus on the obstructive phenotype of hydronephrosis.

 

Ethical approval was sought throughout applying to the Ministerial Ethical Committee to conduct the study and have the proper ethics agreement. Each parent or care giver had signed a consent form that contained full information about the extra study test (the sonography) before setting out the MAG-3 test. The venue of the study was in two professional radiology non-governmental clinics which accommodated referred MAG-3 cases. The two institutes were licenced and specialised for advanced imaging evaluation in Baghdad, Iraq. The sonography assessment and reports were performed and written by the research team while the MAG-3 evaluation was done by the institute’s staff.

 

US was performed pre and post voiding and particularly after 10 minutes of emptying the bladder. All kidney assessments were taken place in an anterolateral scan in a supine position of the child to have transverse renal plane and optimal view. Features of the urinary retention in the pelvicalyceal system (PCS) were assessed by measuring the antero-posterior diameter (APD) of the renal pelvis at the hilum; the parenchymal thickness (PT) and the calyceal dimension(CD) in millimetres.

 

The PCS was tabulated based on the APD as ‘not dilated PCS’ versus ‘dilated PCS’ with a cut off more than 14 mm to be dilated²³. PT was also tabulated as ‘normal’ versus ‘significantly decreased’ if the measurement was less than 10 mm to be significantly decreased¹⁶. Calyceal dimension was tabulated as ‘not dilated CD’ versus ‘dilated CD’ if the measurement was less than 6 mm to be considered as not dilated²⁴.

 

 

MAG3 was performed according to the protocol tubular secretion and furosemide challenge. Patients were given 10–20mL/Kg of water orally 30–40 min before the test; i.e., there was a minimum duration of 30 minutes between performing the post-void US and the MAG3 studies. The test required an intravenous (IV) injection of 12µci/kg Technetium-99m MAG3 tracer with a minimum activity of 150µci²⁵. A large field of view gamma camera equipped with a low energy all-purpose collimator was used. The window was placed over the photo peak of the tracer and was opened by 20%. A 128 x 128 image matrix was used. Data were collected in 12-second time frames. The scintigraphic examination lasted 40minutes and furosemide was administered along with the tracer. Differential renal function (DRF) was calculated using the number of counts in each kidney during the same time interval of 1-2 min after background correction using a one-pixel perirenal area. DFR was considered abnormal if it was <45% and normal if it was ≥45%.

 

The quality of renal drainage (QRD) was evaluated on the basis of the entire renogram, including the residual post-micturition activity. QRD was described as poor when the persistence of high renal activity on the postmicturition with normalized residual activity was more than 2 oras good when almost complete renal emptying and normalized residual activity postmicturition was less than 2. The activity and the half-life (T½) of renal signal decay (RSD) after furosemide administration of each kidney was categorized as being normal (T ½ of less than 11 minutes) or abnormal (T ½ more than 10 minutes).

 

RESULTS:

The median age of the sample was two years and four months with mean kidney length 8.2 millimetres and 3.5 width based on our readings. Majority of cases (32 out of 35) were lacking documented measurements of PCS and PT while more than two thirds (24 case) were without APD measurements using US though they were referred to the MAG-3 test. According to our US measurement, 21(±10.3) mm was the mean APD of the PCS. There was not a prominent difference between the measurements of APD between pre and post void exceeding 2 millimetres in only 3 cases. Therefore, all the statistical tests were done for the pre-void readings.

 

The statistics were performed using the statistical package of social sciences software (SPSS) version 24. Cross-tabulation was done for descriptive statistics and the Fisher-exact test of chi-square test (χ²) was done for categorical data. Correlations between continuous data were tested using Pearson’s test for normally distributed data and Spearman’s test for not normal. P-value was considered as significant if it was less than 0.05.

 

The correlation between age and APD of PCS was negatively related to each other (-0.068) though it was not significant. Results revealed a clear statistical significance between normal differential renal function and the good quality of renal drainage of Mag-3 test with the undilated PCS category (p-value 0.028) when measured by our team using the sonography technique. Other results of the calyceal dimension (CD) and the parenchymal thickness (PT) have failed to obtain a statistical significant difference when compared with the categories of the three variables of MAG-3 (table 2).  

 

 

Figure 1: Measurement of APD of PCS, parenchymal thickness (PT), and calyceal dimension (CD) using sonography imaging

 

Table 01: Characteristics of the study sample (n=35)

APD= anteroposterior diameter; CD =calycealdimension; DRF = differential renal dilatation;

MAG-3 =^99mTc chelation with mercaptoacetyltriglycine; PCS =pelvicalyceal system; PT = parenchymal thickness;

QRD = quality of renal drainage; RSD =renal signal decay.

 

Table 2: Pelvicalyceal dilatation using APD in ultrasound versus normal or good renal function or drainage using MAG-3 (n=35)

* 1-sided Fisher-exact test of χ2

 

 

  

Figure 2: Measurement of DFR, QRD, and T½ of renal signal decay using dynamic MAG-3 scintegraphy scan

 

 

 

DISCUSSION:

The detection of the cause of presumed hydronephrosis is one of the main controversies in pediatric urology. The debate is how to carefully detect and send for sensitive further rational objective evaluation. A plethora of children are subjected to invasive scans involving ionizing radiation and radioisotope exposure during cumbersome procedures that involve intravenous insertion and urethral catheterization where they indeed do not require those tests at least not in the accurate timing^26,27. Therefore, a reduction in functional renogram would result in cost savings to the patient and health system as well as reduction in harmful exposures to young patients. Having any patient with hydronephrosis previously detected incidentally or prenatally prepared for MAG-3 test was the main inclusion criterion because we thought that there are a lot of irrational or false positive results in ultrasonography especially among young children. Many international guidelines have underlined various pitfalls in the evaluation of sensitive parameters when considering the referral for the MAG-3 scintigraphy.

 

DRF represents one of the highly reliable parameters for further evaluation of a follow-up hydronephrosis pediatric case²⁸. In our study, DRF along with the QRD factors were concluded as sensitive evaluators matching the results of the sensitive sonography²⁹. Good or partial QRD has been correlated with no severe obstruction a clinically³⁰ and it was directly related to lower undilated APD in this study. It seemed therefore interesting to determine if some US parameters could predict the reproducible scintigraphy parameters to rely on before sending for radio-nucleotide scanning. The initial step was to grade the categories of pelvicalyceal dilatation by measurement at the hulim of the pelvis along with assessment of calyceal dimension and parenchymal thickness or cortical thinning.

In line with number of clinical and experimental studies that suggest that some hydronephrosis cases are not pathologic but instead represents a compensating mechanism created by the kidney autonomic function to temporarily protect the kidney from high pressures and renal damage^31,32,33,34, this study has found that APD dilatation of the PCS may not be directly related to poor renal function of drainage. 

 

CONCLUSION:

This study supports the inference of assessing renal function based on sensitive parameters of evolutionary sonography. Each radiologist / nephrologist / urologist should evaluate the measurement of reliable parameters of sonography especially the anteroposterior diameter of the pelvicalyceal system (APD of PCS) at the hilum area and the parenchymal thickness (PT) in millimeters and set the pediatric patient for logical follow-up before recommending the dynamic scintigraphy tests. Reducing the exposures from invasive testing should be a motive and real intention to improve selectivity of the children who are investigated with dynamic scintigraphy testing.

 

LIMITATIONS:

This study has a number of limitations including the scarce of cases and the selection of patients which was based on one scintigraphy canter that may receive biased cases referred from particular urologists. Therefore, generalize ability for all renal renogram centres might not be accurate. 

 

REFERENCES:

1.     Capolicchio J-P, Braga LH, Szymanski KM. Canadian Urological Association/Pediatric Urologists of Canada guideline on the investigation and management of antenatally detected hydronephrosis. Canadian Urological Association Journal. 2018; 12(4): 85-92. doi:10.5489/cuaj.5094

2.     Akshay G, Rutuja S, Shreya P, Prajakta K. Polycystic ovary syndrome: An Overview, Diagnosis and Treatment of PCOS. Asian Journal of Pharmacy and Technology. 2020; 10(4): 265-272. DOI: 10.5958/2231-5713.2020.00044.6

3.     Kohno M, Ogawa T, Kojima Y, Sakoda A, Johnin K, Sugita Y, et al. Pediatric congenital hydronephrosis (ureteropelvic junction obstruction): Medical management guide. International Journal of Urology. 2020; 27(5): 369-376. doi: 10.1111/iju.14207.

4.     Nguyen HT, Herndon CD, Cooper C, Gatti J, Kirsch A, et al. The Society for Fetal Urology consensus statement on the evaluation and management of antenatal hydronephrosis. Journal of Pediatric Urology. 2010; 6(3): 212-231. doi: 10.1016/j.jpurol.2010.02.205.

5.     Karnak I, Woo LL, Shah SN, Sirajuddin A, Kay R, Ross JH. Prenatally detected ureteropelvic junction obstruction: clinical features and associated urologic abnormalities. Pediatric Surgery International. 2008; 24(4): 395-402. doi: 10.1007/s00383-008-2112-1

6.     Pawar PP, Phadtare DG. Acoustic Mediated Drug Delivery System. Research Journal of Pharmacy Dosage Form. and Technology. 2016; 8(1): 55-65.

7.     Thorup J, Jokela R, Cortes D, Nielsen O. The results of 15 years of consistent strategy in treating antenatally suspected pelvi‐ureteric junction obstruction. BJU International. 2003; 91(9): 850-852.

8.     Frizzell JP. Introductory Concepts and Clinical Perspectives. . Pathophysiology. T. Capriotti. Philadelphia. 2016

9.     Kulchenko NG, Kostin AA, Chibisov SM, Eremina IZ, et al.. Modern Principles of Early Diagnosis of Prostate Cancer. Research Journal of Pharmacy and Technology. 2017; 10(3): 696-698. DOI:10.5958/0974-360X.2017.00130.5

10.   Viteri B, Calle-Toro JS, Furth S, Darge K, Hartung EA, Otero H. State-of-the-Art Renal Imaging in Children. Pediatrics. 2020; 145(2): e20190829. doi: 10.1542/peds.2019-0829.

11.   Alphonsa Pascal, Anitta Mariam Mathew, Biffy Ann Philip, Elena Sebastian, Simi Mariyam Sibi, Jasmine P.V. A Study to assess the Effectiveness of Structured Teaching Programme on knowledge regarding prevention of Urinary Tract Infection among Adolescent girls in selected schools at Kollam District. Asian Journal of Nursing Education and Research. 2019; 9(3): 391-394. doi: 10.5958/2349-2996.2019.00084.3

12.   Ucar AK, Kurugoglu s. Urinary ultrasound and other imaging for ureteropelvic junction type hydronephrosis (UPJHN). Frontiers in Pediatrics. 2020; 8: 546. doi: 10.3389/fped.2020.00546.

13.   Ranga P, John JJ. Evaluation of the thickness of facial anterior gingiva and posterior palatal mucosa by transgingival probing. Research Journal of Pharmacy and Technology. 2015; 8(5): 565-570. doi: 10.5958/0974-360X.2015.00094.3

14.   Choudhari S, Thenmozhi MS. Occurrence and Importance of Posterior Condylar Foramen. Research Journal of Pharmacy and Technology. 2016; 9(8):1083-1085. doi: 10.5958/0974-360X.2016.00206.7

15.   Luo HYS, Wu X, Yang H, Zhang BB, Bleyer M, Chen G. Computed tomography angiography with 3D reconstruction in diagnosis of hydronephrosis cause by aberrant renal vessel: A case report and mini review. Journal of X-Ray Science and Technology. 2018; 26(1): 125-131. doi: 10.3233/XST-17343.

16.   Swapna Mary A, Maheswari Jaikumar. Effectiveness of Structured Teaching Programme Regarding Risk Factors and Prevention of Renal Failure among Adults in Selected Hospitals at Bangalore, Karnataka. Asian Journal of Nursing Education and Research. 2018; 8(1): 149-151. DOI:10.5958/2349-2996.2018.00031.9

17.   Dhull RS, Joshi S, Saha A. Nuclear imaging in pediatric kidney diseases. Indian Pediatrics. 2018; 55(7): 591-597

18.   Banks KP, Farrell MB, Peacock JG, Costello M, Gordon LL. Diuretic Renal Scintigraphy: The State of Practice and a Potential Opportunity for Standardization. Journal of the American College of Radiology. 2021;  18(11): 1556-1563. doi: 10.1016/j.jacr.2021.07.011.

19.   Damasio MB, Bodria M, Dolores M, Durand E, Sertorio F, Wong MCY, et al. Comparative Study Between Functional MR Urography and Renal Scintigraphy to Evaluate Drainage Curves and Split Renal Function in Children With Congenital Anomalies of Kidney and Urinary Tract (CAKUT). Frontiers in Pediatrics. 2020; 7: 527. doi: 10.3389/fped.2019.00527.

20.   Ouda ZA, Kaloub AN, Ali AK. Assessment of DNA Damage in Lymphocytes of RadiationWorkers at Al-Tuwaitha Site using Nuclear Division Index and Hypoxanthine guanine phosphoribosyl transferase (HPRT). Research Journal of Pharmacy and Technology. 2018; 11(7): 2855-2858. doi: 10.5958/0974-360X.2018.00526.7

21.   Błaszczyk M, Cichocki P, Bieńkiewicz M, Dąbrowski J, Płachcińska A, Kuśmierek J. Assessment of the relation between pelvicalyceal dilatation in ultrasound and features of obstructive uropathy in dynamic renal scintigraphy. Nuclear Medicine Review. 208; 21(2): 96-99. doi: 10.5603/NMR.a2018.0021.

22.   Botros, SM, Ali AH. Transverse Comparisons Between Ultrasound and Radionuclide Parameters in Children with Pelvi-Ureteric Junction Obstruction. The Egyptian Journal of Hospital Medicine. 2018; 72(5): 4543-4550. DOI: 10.21608/EJHM.2018.9542

23.   Li B, McGrath M, Farrokhyar G, Braga LH. Ultrasound-based scoring system for indication of pyeloplasty in patients with UPJO-like hydronephrosis. Frontiers in Pediatrics. 2020; 8: 353. doi: 10.3389/fped.2020.00353.

24.   Kadioglu, A. Renal measurements, including length, parenchymal thickness, and medullary pyramid thickness, in healthy children: what are the normative ultrasound values? American Journal of Roentgenology. 2010; 194(2): 509-515. doi: 10.2214/AJR.09.2986.

25.   Duong HP, Piepsz A, Khelif K, Collier F, De Man K, Damry N, et al. Transverse comparisons between ultrasound and radionuclide parameters in children with presumed antenatally detected pelvi-ureteric junction obstruction. European Journal of Nuclear Medicine and Molecular Imaging. 2015; 42(6): 940-946. doi: 10.1007/s00259-014-2965-6.

26.   Sivakumar VN, Indiran V, Sathyanathan BP. Dynamic MRI and isotope renogram in the functional evaluation of pelviureteric junction obstruction: A comparative study. Turkish Journal of Urology. 2018; 44(1): 45-50. doi: 10.5152/tud.2018.08365.

27.   Dibyajyoti S, Milan H, Mayukh J, Suprodip M, Utpal J. Radiopharmaceuticals and Radio Opaque Contrast Media: Practice, Prospects and Potentials. Asian Journal Research of Pharmaceutical Sciences. 2011; 1(1): 4-8.

28.   Erdman L, Skreta M, Rickard M, McLean C, Mezlini A, et al. Predicting obstructive hydronephrosis based on ultrasound alone. International Conference on Medical Image Computing and Computer-Assisted Intervention, Springer. 2020; 12263.

29.   Tondeur M, Nogarède C, Donoso G, Piepsz A. Inter-and intra-observer reproducibility of quantitative renographic parameters of differential function and renal drainage in children. Scandinavian Journal of Clinical and Laboratory Investigation. 2013; 73(5): 414-421. doi: 10.3109/00365513.2013.797597.

30.   Braga LH, McGrath M, Farrokhyar F, Jegatheeswaran K, Lorenzo AJ. Society for Fetal Urology Classification vs urinary tract dilation grading system for prognostication in prenatal hydronephrosis: a time to resolution analysis. The Journal of Urology. 2018; 199(6): 1615-1621. doi: 10.1016/j.juro.2017.11.077.

31.   Nitin M, Ifthekar S. Nephroprotective activity of Vigna mungo (Linn.) Hepper on gentamicin-induced renal damage in albino rats. Research Journal of Pharmacology and Pharmacodynamics. 2012; 4(5): 299-303.

32.   Nogarède C, Tondeur M, Piepsz A. Normalized residual activity and output efficiency in case of early furosemide injection in children. Nuclear medicine communications. 2010; 31(5): 355-358

33.   Carmody JB, Carmody RB. Question from the clinician: management of prenatal hydronephrosis." Pediatric Review. 2011; 32(12): e110-112

34.   Alsubhi MH, Alghanmi AA, Alzabidi YH, Bafail AK, Bafaraj SM. A correlation study of the effectiveness of renal scintigraphy and sonography in the detection and evaluation of renal disorders. 2022; 10(6): 56-65. DOI: 10.4236/jbm.2022.106005

 

 

Accepted on 29.06.2022        © RJPT All right reserved

Research J. Pharm. and Tech 2023; 16(2):733-739.