Indications for 99mtechnetium dimercapto-succinic acid scan in children

Is renal scintigraphy really a necessity in the routine diagnosis of congenital solitary kidney?

BACKGROUND

For a definitive diagnosis of congenital solitary kidney, renal scintigraphy is suggested as being the gold standard of ruling out ectopic functioning renal tissue, possibly missed by ultrasound. The aim of our study was to test ultrasonography precision in comparison with renal scintigraphy on a larger cohort of congenital solitary kidneys.

METHODS

We performed a retrospective unicenter study of children with congenital solitary kidney with no contralateral tissue, who were treated in the period from 1980 to 2017. The findings in children who underwent both abdominopelvic ultrasound and nuclear renal scintigraphy were compared and the accuracy of ultrasound was assessed.

RESULTS

99 children met the inclusion criteria of congenital solitary kidney confirmed with abdominopelvic ultrasound and nuclear renal scintigraphy. The children were predominantly male (61.6%), and the congenital solitary kidney was largely right-sided (55.5%). In 97 cases (98%), ultrasound correctly predicted the absence of functional renal tissue on one side in the renal fossa or in an ectopic location (pelvis or ipsilateral side). The calculated accuracy of abdominopelvic ultrasound in diagnosing congenital solitary kidney was therefore 98%.

CONCLUSIONS

Our findings confirm that abdominopelvic ultrasound alone is accurate enough to diagnose congenital solitary kidney. It gives enough information for consideration if further radiological evaluation is still needed.

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.

Abdominopelvic ultrasound: a cost-effective way to diagnose solitary kidney

PURPOSE

Solitary kidneys are detected on approximately 1 of 1,500 prenatal ultrasounds and during evaluation for other urological complaints. Although renal scintigraphy is currently the gold standard for confirming the diagnosis and ruling out renal ectopia, scintigraphy is associated with radiation exposure, placement of an intravenous line and sedation. We hypothesize that ultrasonography alone is sufficient to detect solitary kidneys and that confirmatory renal scintigraphy is unnecessary.

MATERIALS AND METHODS

We reviewed the records of children with a solitary kidney who underwent ultrasound and nuclear scintigraphy at our institution from 2001 to 2010. Radiological findings were compared to assess the accuracy of ultrasound in diagnosing solitary kidneys. Costs were calculated based on 2011 Medicare global reimbursement.

RESULTS

A total of 25 children met the inclusion criteria of undergoing ultrasound and renal scintigraphy (dimercapto-succinic acid or mercaptoacetyltriglycine scan). The majority of cases were male (16, 64%) and left sided (17, 68%). Median age was 9 days (range 1 day to 11.6 years) at first ultrasound and 4.4 months (3 weeks to 12 years) at first renal scintigraphy. In 24 patients ultrasound correctly diagnosed a solitary kidney as confirmed by nuclear scan. In 1 patient ultrasound suggested a pelvic kidney but repeat ultrasound was negative, as was dimercapto-succinic acid scan. The diagnostic accuracy of ultrasound was 96%. Medicare reimbursement for dimercapto-succinic acid scan (CPT 78700) is $460 to $720 ($222 plus $240 for radiotracer plus $260 for anesthesia, if used).

CONCLUSIONS

Our findings suggest that ultrasonography alone is sufficient to make the diagnosis of solitary kidney. Omitting routine renal scintigraphy saves approximately $460 to $720 per case, and avoids radiation and discomfort without sacrificing diagnostic accuracy.

Primary vesicoureteral reflux mediated renal scarring after urinary tract infection in Thai children

AIM

To evaluate the association between primary vesicoureteral reflux (VUR) and renal scarring in children using 99 m Technetium-labelled dimercaptosuccinic acid (DMSA).

METHODS

Children attending at Songklanagarind Hospital from 1987 to 2002 were evaluated.

RESULTS

Ages at diagnosis of VUR in 46 boys and 52 girls were 1.1+/-1.6 and 2.9+/-2.5 years, median 0.6 and 2.3 years, respectively (P<0.001). DMSA scans were performed at 4.1+/-3.6 years. Renal parenchymal damage was detected in 34 kidneys (22%) of 154 demonstrated refluxing ureters, and one kidney (2%) of 42 non-refluxing ureters (P=0.002). Of 79 refluxing ureters in boys and 75 refluxing ureters in girls, there were 25 and nine renal scars, respectively (32% and 12%, P=0.003). Renal scars in VUR grades I-V were 11%, 7%, 12%, 44% and 64%, respectively (P<0.001). Multivariate analysis revealed that high grade VUR (P<0.001), age of diagnosis of VUR greater than 5 years (P=0.001), and male gender (P=0.002) were the most significant risk factors for renal scarring.

CONCLUSION

High-grade VUR, age of diagnosis of VUR greater than 5 years and male gender were the most significant risk factors for renal scarring.

Estimation of absolute renal uptake with technetium-99m dimercaptosuccinic acid: direct comparison with the radioactivity of nephrectomy specimens

CONTEXT AND OBJECTIVE

Studies using radionuclides are the most appropriate method for estimating renal function. Dimercaptosuccinic acid chelate labeled with technetium-99m (99mTc-DMSA) is the radiopharmaceutical of choice for high-resolution imaging of the renal cortex and estimation of the functional renal mass. The aim of this study was to evaluate a simplified method for determining the absolute renal uptake (ARU) of 99mTc-DMSA prior to nephrectomy, using the radioactivity counts of nephrectomy specimens as the gold standard.

DESIGN AND SETTING

Prospective study at the Division of Nuclear Medicine, Department of Radiology, Universidade Estadual de Campinas.

METHODS

Seventeen patients (12 females; range 22-82 years old; mean age 50.8 years old) underwent nephrectomy for various reasons. Renal scintigraphy was performed three to four hours after intravenous administration of a mean dose of 188.7 MBq (5.1 mCi) of 99mTc-DMSA, which was done six to 24 hours before surgery. The in vivo renal uptake of 99mTc-DMSA was determined using the radioactivity of the syringe before the injection (measured using a dose calibrator) and the images of the syringe and kidneys, obtained from a scintillation camera. After surgery, the reference value for renal uptake of 99mTc-DMSA was determined by measuring the radioactivity of the nephrectomy specimen using the same dose calibrator.

RESULTS

The ARU measurements were very similar to those obtained using the reference method, as determined by linear regression (r-squared = 0.96).

CONCLUSION

ARU estimation using the proposed method before nephrectomy seems to be accurate and feasible for routine use.

Effect of percutaneous nephrolithotripsy on renal function: assessment with quantitative SPECT of (99m)Tc-DMSA renal scintigraphy

PURPOSE

To measure the effect of PCNL on global and regional renal function using quantitative single-photon emission CT (SPECT) measurement of Tc-dimercaptosuccinic acid (DMSA) uptake by the kidneys (QDMSA).

PATIENTS AND METHODS

A series of 47 male and 41 female patients with a mean age of 47 +/- 16 years were studied by sequential QDMSA examinations before and 1.5 to 24 months after PCNL. Among the 67 patients (76%) in whom PCNL was performed using upper- or lower-pole access, the function of the affected and nonaffected poles of the treated kidney was calculated separately.

RESULTS

There was no statistically significant difference in the uptake by the treated kidneys before versus after PCNL (11.9% +/- 5% v 11.6% +/- 5%; t = 0.9; P = 0.368). The total functional volume of the treated kidney was slightly decreased, from 235 cc +/- 62 cc to 224 cc +/- 59 cc (t = 2.7; P = 0.011). The percent of the injected isotope dose per cubic centimeter of tissue of the treated kidney was not affected (0.051 +/- 0.02 v 0.053 +/- 0.02; t = 0.86; P = 0.296). Regional assessment revealed a statistically significant decrease in the functional volume at the PCNL port of entry (91 cc +/- 30 cc v 82 cc +/- 27 cc; t = 2.64; P = 0.013). Regarding the percent of the injected dose per cubic centimeter of renal tissue, no statistically significant difference was found between the area of the kidney that underwent PCNL and the untreated area of the same kidney (0.049 +/- 0.02 v 0.05 +/- 0.02; t = 0.693; P = 0.494). The function of the contralateral kidneys remained unchanged (13.4% +/- 5.2% v 13.6% +/- 4.8%; t = 0.68; P = 0.5).

CONCLUSIONS

Despite the statistically significant decrease in the functional volume of the surgically treated region, neither total percent uptake nor percent of injected dose were reduced significantly. Further studies with long-term follow-up of treated kidneys are required.

The value of radionuclide studies in children with autosomal recessive polycystic kidney disease

PURPOSE

To describe and analyze the appearances of autosomal recessive polycystic kidney disease (ARPKD) on Tc-99m DMSA and Tc-99m HIDA scintigraphy.

MATERIALS AND METHODS

The authors evaluated scintigraphic findings for 13 boys and 9 girls (age range, 2 months to 22.75 years; mean, 7.5 years) with ARPKD. Fourteen children underwent Tc-99m DMSA and 20 underwent Tc-99m HIDA scintigraphy according to European guidelines. Kidney outline, internal structure, tracer uptake, and differential function were analyzed on Tc-99m DMSA images, whereas relative liver lobe sizes, hepatocyte tracer uptake, time to peak, and excretion into the biliary tree and gut were evaluated on Tc-99m HIDA scans.

RESULTS

On Tc-99m DMSA images, loss of kidney outline and internal structure was seen in 75% of the scans, and patchy tracer uptake with focal defects throughout the kidneys, particularly at the poles, was evident in 93%. In 85% of the cases, the Tc-99m DMSA changes did not correlate with the ultrasonographic findings where the kidneys are uniformly affected. Characteristic findings on Tc-99m HIDA scans were enlarged left liver lobe in 80%, a delay in maximal hepatocyte uptake in 68%, delayed tracer excretion into the biliary tree in 32% (with stasis in the prominent intrahepatic biliary ducts in 50% or pooling into the segmentally dilated biliary ducts in 25%), and delayed excretion into the gut in 40% of patients.

CONCLUSIONS

In a child with clinically enlarged kidneys that appear diffusely hyperechoic on ultrasound, the appearances on Tc-99m DMSA imaging strongly support the diagnosis of ARPKD. The Tc-99m HIDA findings, especially of an enlarged left lobe of the liver with bile stasis or dilatation, further support the diagnosis.

The utility of (99m)Tc-DMSA and Tc(99m)-EC scintigraphy for early diagnosis of ifosfamide induced nephrotoxicity

A serious undesired effect of certain cytostatics is their nephrotoxicity. In this study, we investigated the toxic effects of ifosfamide and cisplatin by clinical and biochemical parameters in relation to (99m)Tc-dimercaptosuccinic acid ((99m)Tc-DMSA) and Tc(99m)N, N-ethylenedicysteine (EC) renal scintigraphy. The indicators were urinary beta2-microglobulin levels, tubular resorption of phosphate, urinary protein and glucose excretion, glomerular filtration rate, urinary pH and osmolarity. Thirteen paediatric patients (seven boys and six girls), aged 2-16 years, were investigated. Five patients received only cisplatin, six patients were treated with ifosfamide and cisplatin and two with ifosfamide and carboplatin for various malignancies. All except three patients had normal DMSA uptake (median, 19; range, 16-29%) prior to chemotherapy. The reduction in DMSA uptake was unilateral due to tumour invasion in those three patients. Following chemotherapy, DMSA uptake showed reduction in five patients with or without clinical nephrotoxicity. The observed pattern was decreased renal uptake and elevated bladder activity. Three patients with decreased DMSA uptake had normal tubular maximum phosphate reabsorption, which suggested subclinical injury. Decrease in DMSA uptake and tubular phosphate reabsorption (TPR) was detected simultaneously in two patients. No abnormalities were seen on Tc(99m)-EC scintigraphy to suggest nephrotoxicity in our investigation. However, Tc(99m)-EC clearly demonstrated a reduction in split renal function in children with tumour invasion. In summary, we found that ifosfamide induced tubular injury can be detected with (99m)Tc-DMSA scintigraphy before chemotherapy associated nephrotoxicity is observed by laboratory measurements. Our results also imply that, although a tubular agent, renal scintigraphy performed with Tc(99m)-EC is not able to detect subclinical injury or predict the outcome during treatment.

Randomised controlled trial of three day versus 10 day intravenous antibiotics in acute pyelonephritis: effect on renal scarring

BACKGROUND

Acute pyelonephritis often leaves children with permanent renal scarring.

AIMS

To compare the prevalence of scarring following initial treatment with antibiotics administered intravenously for 10 or three days.

METHODS

In a prospective two centre trial, 220 patients aged 3 months to 16 years with positive urine culture and acute renal lesions on initial DMSA scintigraphy, were randomly assigned to receive intravenous ceftriaxone (50 mg/kg once daily) for 10 or three days, followed by oral cefixime (4 mg/kg twice daily) to complete a 15 day course. After three months, scintigraphy was repeated in order to diagnose renal scars.

RESULTS

Renal scarring developed in 33% of the 110 children in the 10 day intravenous group and 36% of the 110 children in the three day group. Children older than 1 year had more renal scarring than infants (42% (54/129) and 24% (22/91), respectively). After adjustment for age, sex, duration of fever before treatment, degree of inflammation, presence of vesicoureteric reflux, and the patients' recruitment centres, there was no significant difference between the two treatments on renal scarring. During follow up, 15 children had recurrence of urinary infection with no significant difference between the two treatment groups.

CONCLUSION

In children with acute pyelonephritis, initial intravenous treatment for 10 days, compared with three days, does not significantly reduce the development of renal scarring.

CT and 99mTc-DMSA scintigraphy in adult acute pyelonephritis: a comparative study

PURPOSE

The aim of this prospective study was to evaluate the relative value of CT and (99m)Tc-DMSA scintigraphy in the diagnosis of acute pyelonephritis (APN) in adult patients suspected of having urinary tract infection.

METHOD

The study was conducted in 36 patients presenting with symptoms suggestive of urinary tract infection. Plain B-mode sonography, CT with contrast medium, and (99m)Tc-DMSA scintigraphy of the kidneys were performed in all patients. Both CT and (99m)Tc-DMSA scintigraphy were performed within 72 h after admission.

RESULTS

Twelve patients with clinical and biological signs of urinary tract infection had no CT or (99m)Tc-DMSA scintigraphy abnormalities. Among these patients, lower urinary tract infection was found in 10 patients and 2 patients had ureteral obstruction. In the 24 remaining patients, the diagnosis of APN was made. Among these patients, a correlation was found between CT and (99m)Tc-DMSA scintigraphy in 11 cases. In two cases, both examinations were normal, and in nine cases, both were abnormal. In 11 cases of the 13 remaining patients, abnormal CT was found with normal (99m)Tc-DMSA scintigraphy, whereas the 2 last cases had normal CT and abnormal (99m)Tc-DMSA scintigraphy results. In two cases, bilateral lesions found on CT manifested as unilateral abnormalities on (99m)Tc-DMSA scintigraphy images.

CONCLUSION

The diagnosis of APN in adult patients is based on clinical presentation and biological findings. Few studies have compared (99m)Tc-DMSA scintigraphy with CT in the detection of parenchymal involvement in APN. We conclude that CT is more accurate than (99m)Tc-DMSA scintigraphy in the detection of APN lesions in adult patients.

Tc-99m DMSA renal scan in first-time versus recurrent urinary tract infection-yield and patterns of abnormalities

PURPOSE

To determine the yield and patterns of abnormalities noted by Tc-99m DMSA renal imaging in cases of first-time versus recurrent urinary tract infections (UTIs) in children.

MATERIALS AND METHODS

We reviewed 101 Tc-99m DMSA studies performed for 52 first-time and 49 recurrent UTIs in 99 children during a period of 1 year. The average age of the patients was 4.4 years, and the female:male ratio was 7:1. Static images of the kidneys were acquired 2 hours after injection of Tc-99m DMSA in anterior, posterior, and right and left posterior oblique views. SPECT was performed in 9% of the cases. The studies were scored as normal or abnormal.

RESULTS

The yield of abnormal scans in first-time UTIs was 22 (42%) and in recurrent UTI 27 (55%). Three categories of abnormalities were noted: 1) renal cortical defects (55% of the abnormal scans in first-time UTIs and 59% of the abnormal scans in recurrent UTIs; P = 0.40); 2) dilated pelvicalyceal system (27% of the abnormal studies in first-time UTIs and 63% of the abnormal studies in recurrent UTIs; P < 0.01); and 3) renal swelling showing disproportionate function with size (41% of the abnormal scans in first-time UTIs and 22% of the abnormal scans in recurrent UTIs; P = 0.21).

CONCLUSIONS

The high yield of renal abnormalities by Tc-99m DMSA scanning emphasizes the importance of testing all cases of UTI, including patients with a first-time infection. Documentation of the pattern of abnormalities may help in planning for subsequent management of UTIs in these patients.

Tc-99m DTPA renal scintigraphy using deconvolution analysis with six functional images of the mean time to evaluate acute pyelonephritis

In 38 children with proved P-fimbriated Escherichia coli acute pyelonephritis, Tc-99m DTPA dynamic renal scintigraphy in the zoom mode using deconvolution analysis was performed, and the results were compared with those of Tc-99m DMSA scans. From the dynamic study, six functional images of the mean time were generated. Each functional image was analyzed separately to search for focal areas of increased mean time within the kidney contour, especially over the kidney parenchyma. Time-activity curves from these areas were generated and analyzed. Tc-99m DMSA scintigraphy showed generalized or focal decreased uptake in 32 (41.8%) kidneys, and deconvolution analysis of Tc-99m DTPA scintigraphy revealed pathologic renographic curves in 58 (77.6%) kidneys. Prolonged whole-kidney and normal renal parenchymal transit times (dilatation without obstruction) were found in 38 (50%) kidneys, whereas prolonged whole-kidney and renal parenchymal transit times (dilatation with obstruction) were observed in 20 (27.6%) kidneys. Separate analysis of each of the six functional images of the mean time showed focal areas of increased mean time in the kidney parenchyma of 11 kidneys. In five cases, time-activity curves from these areas showed a sharp increase of activity on the descending part of the curve, which might reflect the return of urine from the collecting system into kidney cortex (i.e., intrarenal reflux). These results showed that in a urinary tract with acute pyelonephritis, urodynamic changes may lead to obstructive nephropathy and intrarenal reflux. Tc-99m DTPA renal scintigraphy in the zoom mode using deconvolution analysis with six functional images of the mean time has proved to be a valuable method to evaluate acute pyelonephritis, thus allowing dynamic and morphologic analysis of the urinary tract at the same time.

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

The initial 99mTc-DMSA studies carried out over a four year period in 229 patients with various heterogenic causes of lower urinary tract abnormalities were reviewed. Anatomical damage to the renal parenchyma was graded by means of planar and SPECT studies into a six group classification proposed by Monsour et al.: grade 0 (normal), I (equivocal), II (single defect), III (more than 2 defects), IV (contracted or small) and V (no visualization). Parenchymal uptake of 99mTc-DMSA was quantitated from planar images at 2 hours postinjection by a computer assisted gamma camera method. SPECT studies could enhance the pick-up rate for parenchymal uptake defects by a factor of 1.5 in comparison with planar imaging. The incidence of anatomical damage to the renal parenchyma increased with a high radiological grade for VUR, and renal uptake per injection dose of 99mTc-DMSA by the individual kidney significantly decreased in grades III and IV of the anatomical classification. These data revealed that 99mTc-DMSA planar is still useful for evaluating gross structural damage and for quantitative evaluation of the kidney with computer assistance. SPECT scintigraphy is more effective in disclosing anatomical damage to the renal parenchyma than planar, although it needs further discussion as to whether SPECT may increase sensitivity with minimal or no adverse affect on specificity.

The selective use of dimercaptosuccinic acid renal scans in children with vesicoureteral reflux

Dimercaptosuccinic acid (DMSA) renal scans were performed on 75 children (115 refluxing renal units) to determine the efficacy of routine scanning in patients with various grades of vesicoureteral reflux. Cystourethrography demonstrated grades I and II reflux in 75 renal units and grades III to V in 40. Of the patients 51 presented with febrile urinary tract infection and 24 were asymptomatic (patients presenting with nonfebrile urinary tract infections or those undergoing sibling screening). Renal ultrasounds were performed in 60 patients. All patients were initially managed with medical therapy and 19 (25%) ultimately underwent antireflux surgery. DMSA scans demonstrated scarring in 17 of 40 renal units (43%) of patients with high grade vesicoureteral reflux and 6 of 75 renal units (8%) of those with low grade reflux. Renal ultrasounds that were interpreted as normal always correlated to a normal DMSA scan in asymptomatic patients. In patients presenting with febrile urinary tract infections the correlation between ultrasound and DMSA scan was inconsistent. We advocate a tailored approach in the evaluation of patients with vesicoureteral reflux. Renal sonography may be sufficient in the assessment of renal scarring in asymptomatic patients with reflux and those with low grade reflux. Conversely, in patients with high grade vesicoureteral reflux, a history of febrile urinary tract infections and abnormal renal ultrasound DMSA renal scans appear to be most useful.

Cortical scintigraphy in the evaluation of renal parenchymal changes in children with pyelonephritis

We designed a prospective study to evaluate the ability of dimercaptosuccinic acid cortical scintigraphy and ultrasonography to detect renal parenchymal lesions in children with pyelonephritis. One hundred eleven patients 1 week to 16 years of age (median 5.5 months) with a urine culture positive for pathogens were included in the study; cortical scintigraphy and ultrasonography were repeated in 25 children after a mean follow-up of 10.5 months. Cortical scintigraphy showed renal changes in 74 children (67%), and ultrasonography showed renal changes in 39 (35%) (p < 0.001); results of the two examinations were discordant in 49 patients (kappa = 0.19). Children more than 1 year of age had a higher incidence of renal lesions than did younger children (85% vs 66%; p = 0.04). The presence of inflammatory signs (erythrocyte sedimentation rate or C-reactive protein) had an 89% sensitivity and a 25% specificity in identifying renal lesions. Among children with renal changes, vesicoureteric reflux was present in 39%. At follow-up examination, 16 children (64%) had scars. Thus we found a high incidence of renal involvement in children with pyelonephritis. We found that cortical scintigraphy is more sensitive than ultrasonography in detecting renal changes, and we believe that it should be added to the initial examination of children with suspected pyelonephritis.

Rational use of CT in acute pyelonephritis: findings and relationships with reflux

Enhanced renal CT scanners were performed in 38 children (82% girls) to rule out acute pyelonephritis. Patients were divided in 2 groups on the basis of clinical presentation and bacteriology data. In patients of group A (n = 16, preliminary study), upper urinary tract infection (UTI) was certain. CT confirmed the diagnosis in all but 3 patients (a 2-year-old child and 2 patients with UTI developed on prior obstruction). In subsequently studied patients of group B (n = 22), clinical findings or bacteriology data were negative or questionable. CT made the diagnosis of acute pyelonephritis in 11 patients. As well as DMSA scintigraphy, CT scanner can help to diagnose or to rule out upper UTIs in difficult cases. In all boys of both groups, ipsilateral vesico-ureteric reflux (VUR) was found by subsequent voiding cystourethrography (VCUG) on the side of pyelonephritis. In girls, this correlation was shown in only 7 of the 25 kidneys with pyelonephritis. This result supports the hypothesis of a gender-dependent contamination. We believe that absence of radiologic reflux cannot exclude the possibility of bacterial crossings of ureteric meatus capable to lead to genuine upper UTIs.

Involvement of the renal parenchyma in acute urinary tract infection: the contribution of 99mTc dimercaptosuccinic acid scan

We performed 99mTc dimercaptosuccinic acid (DMSA) scan and ultrasonography in 146 children during the acute phase of a proven urinary tract infection (UTI). In 99 a micturating cysto-urethrography and in 83 an intravenous urography was also done. The occurrence of fever and increased WBC count, CRP and ESR were also studied. It appeared from this retrospective study that 47% of the kidneys had a cortical or patchy pattern of decreased uptake of 99mTc DMSA, as compared to 23% with abnormal findings on US. Vesico-ureteral reflux was present in 38% of the kidneys with parenchymal involvement on 99mTc DMSA scan. Although fever, leucocytosis and elevated CRP and ESR were significantly correlated with abnormal 99mTc DMSA scan, they were also observed in children without renal parenchymal involvement. Our results suggest that 99mTc DMSA scan is a sensitive method for the detection of parenchymal involvement during acute UTI. The exact nature of these lesions and their relation with scars need, however, to be defined.

Single photon emission computed tomography with Tc-99m-dimercaptosuccinic acid in patients with upper urinary tract infection and/or vesicoureteral reflux

By means of Tc-99m dimercaptosuccinic acid (DMSA) scintigraphy, an established method for assessing renal cortical damage, we evaluated the pick-up rate for renal defects (scars) by single photon computed tomography (SPECT) and planar images of 10 normal volunteers, and 58 patients (70 scintigrams) with upper urinary tract infections, most of whom had a history of vesicoureteral reflux (VUR). The positive study rate for renal defects depended on the severity of VUR. The overall positive rates for renal cortical defects obtained by DMSA SPECT imaging and DMSA planar imaging were 60% and 43%, respectively, and the difference between these was significant (p less than 0.005). The mean absolute individual renal uptake (/injected dose) at 2 hours post-injection was decreased in kidneys with defects detected by SPECT alone. The positive study rate for intravenous urography (IVU) depended on the grade of VUR and was 15% overall. DMSA SPECT imaging detects renal cortical defects at greater frequency than previously achieved.

Renal cortical scintigraphy and single proton emission computerized tomography (SPECT) in the assessment of renal defects in children

Single photon emission computerized tomography (SPECT) is finding greater clinical applicability in pediatric imaging. We applied the principles of SPECT imaging to renal cortical scintigraphy in the assessment of renal defects. We evaluated retrospectively 35 children who were undergoing 99mtechnetium-glucoheptonate renal cortical scintigraphy. Each child underwent planar, SPECT and pinhole imaging. Of the 35 children 9 had normal systems bilaterally and the remaining 26 had at least 1 defect in 1 or both kidneys. Over-all, we identified 29 abnormal renal units. Planar imaging identified 59% of the defects, while pinhole and SPECT imaging identified 83% of the defects. When combining any 2 studies (that is planar and pinhole, planar and SPECT or pinhole and SPECT) we were able to identify 97% of the defects, which approached but was not statistically significant at p = 0.09. When data from all 3 studies were combined 100% of the defects were identified, which was a statistically significant increase in defects noted when compared to only planar images (p = 0.016). SPECT imaging was found to be a technically feasible undertaking with conventional equipment, although its clinical applicability at this time is limited.

Comparison of 99Tcm dimercaptosuccinic acid scans and intravenous urography in children

A retrospective comparison of 99Tcm dimercaptosuccinic acid (DMSA) scans and intravenous urograms (IVUs) was performed on a large, unselected paediatric population to assess critically the relative merits of these two techniques. A total of 205 children were studied, providing 388 kidneys for comparison. The studies agreed in 81%, both being normal in 39%, and both abnormal in 42%. In 28 kidneys (7%), the IVU was abnormal when the 99Tcm DMSA was normal. There was a collecting system abnormality in 27 kidneys, but 10 kidneys also showed a parenchymal abnormality. In all these the parenchymal abnormality was global thinning on the IVU, and the contralateral kidney was small. In 40 kidneys (10%) the 99Tcm DMSA was abnormal when the IVU was normal: the abnormalities demonstrated were predominantly focal defects. After excluding IVUs of poor diagnostic quality, only 14 kidneys (3.6%) showed this disparity. The important clinical subgroups are infection, with or without reflux (27 kidneys), hypertension (4) and neonates with poor renal function (2). The one false positive 99Tcm DMSA was a result of an anatomical variant. Global thinning in a "normal" kidney on a 99Tcm DMSA scan may be overlooked when the contralateral kidney is poorly functioning and small.

99mTc-DMSA scintigraphy in acute urinary tract infection in children

24 children with symptomatic urinary tract infection (UTI) underwent systematically ultrasound studies (US) and 99mTc-DMSA renal scans. Among the 15 patients considered as acute pyelonephritis (APN) on clinical grounds, the scan was abnormal in 12 cases, in contrast with only 1 abnormal scan in the clinical subgroup of the lower UTI. Among the 10 abnormal scans that were repeated later on, 6 did completely normalize. US showed only once a parenchymal appearance suggestive for APN. Our findings suggest that the DMSA scan has to be considered at present as the most sensitive imaging technique for the detection of APN.

Urography versus DMSA scan in children with vesicoureteric reflux

Following the diagnosis of primary vesicoureteric reflux, identified as part of the investigation of urinary tract infection, 299 refluxing kidneys in 202 children (aged 0-14 years) were prospectively evaluated using intravenous urography (IVU) and the DMSA renal scan at least 4 weeks after urine infection. There was 88% concordance between IVU and the DMSA scan, but in 12% there were discrepancies manifested in 37 kidneys from 31 children. Thirty-four kidneys were normal on IVU but showed scars of reflux nephropathy (RN) on the technetium 99m--dimercaptosuccinic acid (DMSA) renal scan; 4 of these (2 infants and 2 pre-school children) had severe generalized changes on scanning. Three kidneys were normal of DMSA scan and, although abnormal on initial IVU, were considered to be normal when this was repeated. During a follow-up period of 5 years an annual DMSA was undertaken in 194 patients and the renal scars remained unchanged in all except 1 child. The IVU was repeated 1-3 years after the initial study in 31 children in which the results of the first imaging did not agree. In 28 patients (34 kidneys) in which the initial IVU was normal but the DMSA abnormal, IVU evidence of scarring emerged in 30 of 34 kidneys, including the 4 patients with severe generalized damage on the DMSA. We conclude that abnormalities detected by the DMSA scan may precede the radiological findings, especially in young children. Even severe RN can be established in kidneys that appear normal on the IVU.

Optimal use of 99mtechnetium-glucoheptonate scintigraphy in the detection of pyelonephritic scarring in children: a preliminary report

Renal scintigraphy represents the optimal modality for the detection of renal scars. 99mTechnetium-glucoheptonate is rapidly accumulated by the kidney through glomerular filtration and active transport by renal tubular cells. This permits rapid visualization of the renal parenchyma in the early phase (1 to 3-minute images) and subsequent imaging of the collecting system and ureters. About 10 to 15 per cent of the injected activity remains in the kidney, labeling the cells of the proximal convoluted tubules (late phase or 1 to 2-hour images). The late phase has been used more commonly to assess renal parenchymal damage. Early and late phase glucoheptonate scanning was performed in 42 children as part of the evaluation of recurrent febrile urinary tract infections with or without a history of vesicoureteral reflux. Inter-observer reliability to interpret glucoheptonate scans was good (early, 83 per cent agreement and late, 93 per cent agreement). The ability of glucoheptonate scanning to detect renal scarring in children with febrile urinary tract infections was equivalent with the early or late phase of the study. In 6 patients renal scarring was detected on only the early phase scan and in 7 scarring was detected only in the late phase. Although the detection rates are equivalent the over-all detection of scarring is improved by using both phases. Therefore, the early phase of the glucoheptonate scan may be a valuable adjunct to conventional glucoheptonate scan methodology used for the detection of renal scarring in children with recurrent urinary tract infections.

Evaluation of 99mtechnetium-dimercapto-succinic acid renal scans in experimental acute pyelonephritis in piglets

We evaluated the sensitivity and specificity of 99mtechnetium-dimercapto-succinic acid renal scans in the detection and localization of experimental acute pyelonephritis in piglets. To create pyelonephritis vesicoureteral reflux of infected urine was surgically induced in 22 piglets. Nine animals were evaluated with a dimercapto-succinic acid renal scan at 1 week and 13 at 2 weeks. Autopsy and histopathological examination of the kidneys were performed subsequently. The location and extent of the inflammatory response found on histopathological examination were compared to dimercapto-succinic acid renal scan findings in a blinded fashion. Of the 22 kidneys subjected to vesicoureteral reflux 15 had positive histopathological findings of acute pyelonephritis, including 13 detected by the dimercapto-succinic acid renal scan findings. The 2 kidneys in which inflammation was not detected had only minimal grade I lesions and were grossly normal. There were no false positive scans in any of these kidneys. The sensitivity of the scan for detection of acute pyelonephritis in the kidneys subjected to reflux was 87 per cent and the specificity was 100 per cent. Furthermore, in these same kidneys the dimercapto-succinic acid renal scan findings correctly predicted the presence or absence of individual pyelonephritic lesions in 62 of 66 poles for an over-all agreement rate of 94 per cent. Thus, dimercapto-succinic acid renal cortical imaging is a highly sensitive and reliable imaging modality to detect and localize experimental acute pyelonephritis in piglets.

99mTc dimercaptosuccinic acid (DMSA) scan in patients with established radiological renal scarring

The findings on 99mTc dimercaptosuccinic acid (DMSA) scans were examined in 54 patients aged 3 to 33 years in whom renal scarring had been diagnosed radiologically in childhood after urinary tract infection. There was no recent history of infection. Vesicoureteric reflux had been present in 48 patients and had stopped in 23 at the time of the DMSA scan. In six of the 72 radiologically scarred kidneys, the DMSA scan appeared normal but scarring would have been overlooked in only two of the 54 patients. DMSA scan changes are non-specific and underestimated individual scars in 21 kidneys. The intravenous urogram and the DMSA scan showed good correlation but should be regarded as complementary investigations in these patients, giving morphological and functional information, respectively. On DMSA scans the timing of any preceding urinary tract infection must be considered in order to differentiate diffuse potentially reversible defects in isotope uptake after urinary tract infection from those due to permanent renal scarring.

Two routes for 99mTc-DMSA uptake into the renal cortical tubular cell

Critical factors determining the renal handling of 99mTc-dimercaptosuccinic acid (DMSA) are protein binding in plasma and the renal 99mTc-DMSA extraction efficiency. Comparison of the count rate over soft tissue with that over the cardiac blood pool about 1 h after injection demonstrated that 99mTc-DMSA is not exclusively an intravascular label. 99mTc-DMSA was 76% protein bound in plasma as demonstrated by HPLC and gel filtration. Assuming that the 24% that is not protein bound is filtered at the glomerulus, the renal extraction efficiency of 99mTc-DMSA by glomerular filtration is about 5%. Since the total renal extraction efficiency was also found to be about 5%, the majority of the activity that becomes fixed in the renal cortex arrives there as a result of filtration followed by tubular reabsorption rather than by direct extraction from peritubular blood. However, discordant changes in DMSA and DTPA uptake induced by captopril in renovascular hypertension (RVH) suggested that a minority of uptake was by direct peritubular extraction. This kinetic model was supported by indirect measurement of protein binding and extraction efficiency based on the kinetics of 99mTc-DMSA disappearance from plasma and kinetics of uptake in the kidneys. Furthermore, differential functional studies based on 99mTc-DMSA and 99mTc-DTPA before and after captopril in patients with RVH due to unilateral renal artery stenosis confirmed filtration followed by tubular reabsorption as the predominant route for DMSA uptake by the kidney.

Clinical applications of nuclear medicine

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