Qualitative and quantitative evaluation of renal parenchymal damage by 99mTc-DMSA planar and SPECT scintigraphy

Prediction of renal cortical defect and scar using neutrophil-to-lymphocyte ratio in children with febrile urinary tract infection

AIM

This study is aimed to evaluate the predictive value of the neutrophil-to-lymphocyte ratio (NLR) for cortical defect on initial and follow-up Tc-99m dimercaptosuccinic acid (DMSA) scan in children with the first febrile urinary tract infection (UTI).

METHODS

We retrospectively enrolled 179 children with the first febrile UTI who underwent DMSA scan and laboratory tests. In patients with abnormal DMSA scan findings, follow-up DMSA scan was performed at least 6 months after the initial scan. All DMSA scans were classified as negative and positive cortical defects. Multiple logistic regression analyses were performed to identify the risk factors for cortical defect on initial and follow-up DMSA scan.

RESULTS

Cortical defects on initial DMSA scan were noted in 133 patients. Vesicoureteral reflux (VUR), white blood cell count, absolute neutrophil count, NLR, and serum C-reactive protein level were independent predictive factors for positive cortical defect on initial DMSA scan (p < 0.050). On follow-up DMSA scan, 24 of the 133 patients showed persistent cortical defects, and only VUR was significantly associated with persistent cortical defect (p = 0.002). In 84 patients who showed cortical defect on initial scan and absence of VUR, only NLR was significantly associated with persistent cortical defect on follow-up scan (p = 0.025).

CONCLUSION

NLR was significantly associated with persistent cortical defect on follow-up DMSA scan in patients without VUR, as well as positive cortical defect on initial scan.

Estimation of Split Renal Function With 99mTc-DMSA SPECT: Comparison Between 3D Volumetric Assessment and 2D Coronal Projection Imaging

OBJECTIVE

Split renal function (SRF) can be estimated with ^99mTc-labeled dimercaptosuccinic acid (DMSA) SPECT cortical renal scintigraphy on either 2D projected images or 3D images. The purpose of this study was to determine whether there is a significant difference between SRF values calculated with the 2D method and those calculated with the 3D method.

MATERIALS AND METHODS

This retrospective study was performed with ^99mTc-DMSA SPECT images of 316 patients (age range, 1-26 years). All images were reconstructed by filtered back projection. An automated computational method was developed to estimate SRF using both 2D projection images and direct 3D images. A paired t test was used to evaluate the difference between SRFs determined with the two methods and the association between the magnitude of the differences and kidney size, patient age, and SRF.

RESULTS

There was strong correlation between SRFs estimated with the 2D and 3D methods (r = 0.94, p < 0.001). There was small significant difference (0.14% ± 0.86%, p = 0.003) in SRFs obtained with the two methods. The difference was clinically negligible and independent of renal length (p = 0.698), volume (p = 0.297), and patient age (p = 0.768) but was associated with SRF (p = 0.018).

CONCLUSION

For determination of split renal function, ^99mTc-DMSA SPECT renal scintigraphy 2D coronal projection images perform as well as and are simpler to analyze than 3D images.

Predictive Factors of Chronic Kidney Disease in Patients with Vesicoureteral Reflux Treated Surgically and Followed after Puberty

PURPOSE

We delineated clinical features and determined predictors of chronic kidney disease during long-term postpubertal followup in patients with vesicoureteral reflux treated surgically.

MATERIALS AND METHODS

We analyzed the data of 101 patients who were surgically treated for vesicoureteral reflux and had gone through puberty. Patients underwent preoperative and postoperative voiding cystourethrography to assess reflux status, and dimercaptosuccinic acid scan to assess renal cortical defects. We compared several variables preoperatively and postpubertally, including body mass index; blood urea nitrogen, creatinine and uric acid levels; estimated glomerular filtration rate; microalbuminuria; blood pressure; renal function and renal scarring. Kaplan-Meier analysis was used to predict chronic kidney disease-free survival rates throughout the followup periods. Cox regression model was adopted to identify independent predictors of chronic kidney disease. We defined chronic kidney disease as estimated glomerular filtration rate less than 60 ml/minute/1.73 m(2).

RESULTS

Median followup was 100.0 months (IQR 69.0 to 136.5). Median age was 16 years at last followup (IQR 14 to 18). A total of 11 patients (10.9%) were diagnosed with de novo chronic kidney disease during postpubertal followup. It is noteworthy that serum uric acid levels (HR 1.96) and presence of high grade reflux (HR 7.40) were significant predictors of chronic kidney disease on multivariate analysis.

CONCLUSIONS

In children who were treated surgically for vesicoureteral reflux preoperative uric acid levels and high grade reflux were independent predictors of de novo chronic kidney disease during postpubertal followup. Our results offer valuable information for predicting long-term renal outcomes in patients with vesicoureteral reflux treated surgically.

Technetium-99m dimercaptosuccinic acid scan in evaluation of renal cortical scarring: Is it mandatory to do single photon emission computerized tomography?

Objectives:

Renal cortical scintigraphy with technetium-99m (Tc-99m) dimercaptosuccinic acid (DMSA) is the method of choice to detect acute pyelonephritis and cortical scarring. Different acquisition methods have been used: Planar parallel-hole or pinhole collimation and single photon emission tomography (SPECT). This study compared planar parallel-hole cortical scintigraphy and dual-head SPECT for detection of cortical defects.

Patients and Methods:

We retrospectively reviewed 190 consecutive patients with 380 kidneys and 200 DMSA scans referred to rule out renal cortical scarring. The diagnoses were 52 vesicoureteric reflux, 61 recurrent urinary tract infection, 39 hydronephrosis, 20 renal impairment, and 18 hypertension. All patients were imaged 3 h after injection of Tc-99m DMSA with SPECT and planar imaging (posterior, anterior, left, and right posterior oblique views). For each patient, planar and SPECT images were evaluated at different sittings, in random order. Each kidney was divided into three cortical segments (upper, middle and lower) and was scored as normal or reduced uptake. The linear correlation coefficient for the number of abnormal segments detected between planner and SPECT techniques was calculated.

Results:

From 200 DMSA scans, 100 scans were positive for scar in SPECT images, from which only 95 scans were positive for scar in planner imaging. Out of the five mismatched scans, three scans were for patients with renal impairment and high background activity and two scans were for very small scars. No significant difference was seen in the average number of abnormal segments detected by planar versus SPECT imaging (P = 0.31). The average correlation coefficient between was high (r = 0.91 – 0.92).

Conclusions:

Tc-99m DMSA renal cortical scanning using SPECT offers no statistically significant diagnostic advantage over multiple views planar imaging for detection of cortical defect.

Evaluation of interobserver variability of parenchymal phase of Tc-99m mercaptoacetyltriglycine and Tc-99m dimercaptosuccinic acid renal scintigraphy

Objective:

The aim of this study was to investigate the variability in the interpretation of parenchymal abnormalities and to assess the differences in interpretation of routine renal scintigraphic findings on posterior view of technetium-99m dimercaptosuccinic acid (pvDMSA) scans and parenchymal phase of technetium-99m mercaptoacetyltriglycine (ppMAG3) scans by using standard criterions to make standardization and semiquantitative evaluation and to have more accurately correlation.

Materials and Methods:

Two experienced nuclear medicine physicians independently interpreted pvDMSA scans of 204 and ppMAG3 scans of 102 pediatric patients, retrospectively. Comparisons were made by visual inspection of pvDMSA scans, and ppMAG3 scans by using a grading system modified from Itoh et al. According to this, anatomical damage of the renal parenchyma was classified into six types: Grade 0-V. In the calculation of the agreement rates, Kendall correlation (tau-b) analysis was used.

Results:

According to our findings, excellent agreement was found for DMSA grade readings (DMSA-GR) (tau-b = 0.827) and good agreement for MAG3 grade readings (MAG3-GR) (tau-b = 0.790) between two observers. Most of clear parenchymal lesions detected on pvDMSA scans and ppMAG3 scans identified by observers equally. Studies with negative or minimal lesions reduced correlation degrees for both DMSA-GR and MAG3-GR.

Conclusion:

Our grading system can be used for standardization of the reports. We conclude that standardization of criteria and terminology in the interpretations may result in higher interobserver consistency, also improve low interobserver reproducibility and objectivity of renal scintigraphy reports.

Imaging of renal scarring

Children with urinary tract infection should be investigated and followed up, as those with pyelonephritis may develop renal scarring. In this review, after discussing the advantages and disadvantages of various imaging modalities for diagnosis of renal scarring, it is concluded that DMSA scintigraphy and urography can both be used to detect significant renal scarring. With DMSA scintigraphy, small renal lesions (functional uptake defects) not seen at urography will also be detected. The long-term clinical significance of these lesions is, as yet, unknown. A normal DMSA scintigraphy after infection indicates low risk for clinically significant damage. In order to allow acute, reversible lesions to first disappear, a follow-up DMSA examination should not be performed until at least 6 mo after the acute infection. Ultrasonography in isolation cannot be recommended for the diagnosis of renal scarring.

The true clinical significance of renography in nephro-urology

Isotopic renography is a non-invasive technique used routinely by the clinician to provide information about kidney structure and function. Whilst there is no doubt of its value in the accurate measurement of glomerular filtration rate and in the detection of parenchymal abnormalities, its role in the diagnosis of renovascular disease (especially in patients with renal insufficiency), the exclusion of obstruction and the evaluation of the patient with either acute renal failure or renal transplant dysfunction remains unproven. In part, this reflects a failure to standardise protocols and rigorously evaluate diagnostic techniques. Recent developments in ultrasound, computerised X-ray tomography and nuclear magnetic resonance now present the clinician with rival techniques and emphasise the need for the clinical development of isotopic renography.