Scintigraphic evaluation of pediatric urinary tract infection

Effectiveness of the smoothing filter in pediatric 99mTc-dimercaptosuccinic acid renal scintigraphy

The present study aimed to evaluate whether the use of a smoothing filter would improve the image quality in pediatric ^99mTc-dimercaptosuccinic acid (^99mTc-DMSA) scintigraphy. We retrospectively reviewed 31 kidneys in 16 consecutive pediatric patients aged 10 months to 14 years. The administered dose was calculated using a weight-based method. Two reviewers randomly evaluated the original planar posterior images and smoothing filter image; they assessed image quality and performed defect evaluations. The evaluation of visual image quality yielded significantly better results for the smoothing filter images than for the original images. Although the smoothing filter images were slightly inferior to the original images in terms of edge sharpness, no significant difference was observed in the defect evaluation. We confirmed that ^99mTc-DMSA scintigraphy with a smoothing filter yielded reduced image noise, while maintaining defect evaluation performance and improving image quality.

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.

Discordant findings on dimercaptosuccinic acid scintigraphy in children with multi-detector row computed tomography-proven acute pyelonephritis

PURPOSE

The diagnosis of acute pyelonephritis (APN) is often difficult, as its clinical and biological manifestations are non-specific in children. If not treated quickly and adequately, however, APN may cause irreversible renal damage, possibly leading to hypertension and chronic renal failure. We were suspecting the diagnostic value of (99m)Tc-dimercaptosuccinic acid (DMSA) scan by experiences and so compared the results of DMSA scan to those of multi-detector row computed tomography (MDCT).

METHODS

We retrospectively selected and analyzed 81 patients who were diagnosed as APN by MDCT during evaluation of their acute abdomen in emergency room and then received DMSA scan also for the diagnostic work-up of APN after admission. We evaluated the results of imaging studies and compared the diagnostic value of each method by age groups, <2 years (n=45) and ≥2 years (n=36).

RESULTS

Among total 81 patients with MDCT-proven APN. DMSA scan was diagnostic only in 55 children (68%), while the remaining 26 children (32%) showed false negative normal findings. These 26 patients were predominantly male with average age of 21 months and most of them, 19 (73.1%) were <2 years of age.

CONCLUSION

DMSA scan has obvious limitation compared to MDCT in depicting acute inflammatory lesions of kidney in children with APN, especially in early childhood less than 2 years of age. MDCT showed hidden lesions of APN, those were undetectable through DMSA scan in children.

Comparison of 99mTc-DMSA dual-head SPECT versus high-resolution parallel-hole planar imaging for the detection of renal cortical defects

OBJECTIVE

Renal cortical scintigraphy with (99m)Tc dimer captosuccinic acid (DMSA) is the standard method 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). Publications support the superiority of each; few comparative studies have been reported, with mixed results. We have compared planar parallel-hole cortical scintigraphy and dual-head SPECT for detection of cortical defects.

MATERIALS AND METHODS

Forty patients (37 children, 3 adults; 9 male, 31 female) were imaged 3 hours after injection of (99m)Tc-DMSA with dual-head SPECT and planar imaging (posterior, left, and right posterior oblique views with a parallel-hole collimator). For each patient, planar and SPECT images were evaluated at different sittings, in random order, by three independent observers. Twelve cortical segments were scored as normal or reduced uptake. The linear correlation coefficient for the number of abnormal segments detected between readers, techniques, and segments was calculated.

RESULTS

No significant difference was seen in the average number of abnormal segments detected by planar versus SPECT imaging; 2.1 for planar imaging and 2.2 for SPECT (p = 0.84, two-tailed). For all observers, the average correlation coefficient for SPECT alone, planar imaging alone, and between techniques (SPECT vs planar imaging) was high (r = 0.93-0.94). Applying nonparametric Spearman's rank analysis, the average correlation remained high (r = 0.70-0.75). Correlation between readers, techniques, and segments for methods and readers was also good (r = 0.69-0.77).

CONCLUSION

(99m)Tc-DMSA renal cortical imaging using dual-head SPECT offers no statistically significant diagnostic advantage over planar imaging for detection of cortical defects.

Comparison of direct radionuclide cystography and voiding direct cystography in the detection of vesicoureteral reflux

PURPOSE

The aim of this study is to compare the results of direct radionuclide cystography (DRNC) and voiding cystourethrography (VCUG) in a group of children with a high suspicion of vesicoureteral reflux (VUR).

METHODS

For this purpose, 25 children were studied with both VCUG and DRNC. Among 50 ureter units able to be compared 39 ureter units did not show any VUR on either study. Eleven ureter units (10 children) had VUR either on one study or on both (VCUG and DRNC). In the children who had VUR on either study, a dimercaptosuccinic acid scintigraphy (DMSA) was performed to determine their cortical function.

RESULTS

We identified the following four patterns: 1) Five ureter units (five children) read positive on DRNC who were negative on VCUG and four of these children had positive findings on DMSA; 2) Four ureter units (four children) read positive on VCUG who were negative on DRNC, and two of them had positive findings on DMSA; 3) Two ureters (one child) read positive in both studies and also had abnormal DMSA findings; 4) Thirty-nine ureter units read as negative on both studies.

CONCLUSION

Although the results of these two methods did not show a significant difference, DRNC offers a high sensitivity in the younger age group whereas VCUG seems to be more sensitive in the older age group. DRNC also offers continuous recording during the study, ease of assessment and lower radiation dose to the gonads, which makes it a preferable method for the initial diagnosis and follow-up of VUR.

The role of indirect radionuclide cystography during the acute phase of pyelonephritis in young women

OBJECTIVE

To review our experience using dynamic 99mTc-diethylenetriamine penta-acetic acid renal scintigraphy combined with indirect radionuclide cystography (IRC) in the acute phase of pyelonephritis, as a possible alternative to the conventional imaging, as investigating acute pyelonephritis usually includes imaging the upper urinary tract during the acute phase, to exclude obstruction, and delayed voiding cysto-urethrography (VCUG) when underlying vesico-ureteric reflux (VUR) is suspected.

PATIENTS AND METHODS

Between 1997 and 1999, 47 young women (median age 22 years, range 18-37) were hospitalized for acute pyelonephritis. The combined study was used during the acute phase of the disease, usually within 24 h of hospitalization. The principle of IRC is based on the reappearance of radioactivity in the ureters or kidneys after previously detecting renal clearance of an intravenously injected radioisotope. The increase in radioactivity over the ureters or kidneys indicates VUR. The subsequent follow-up included VCUG, after recovery and at least 6 weeks after discharge.

RESULTS

Overall, 47 patients had early IRC studies; obstruction of the urinary tract during the acute phase of the disease was excluded in all. In 13 (28%) of the patients early IRC studies showed VUR involving 21 upper tract units. The renal parenchymal scan was impaired in 17 (36%) patients, and six of these 17 also had detectable concomitant reflux on IRC. Overall, 24 IRC studies (51%) were considered positive, showing VUR, renal parenchymal pathology or both; 23 (49%) were normal. Follow-up VCUG was used in 32 patients (68%); only three (9%) detected VUR. All of the patients with VUR on follow-up VCUG had also had an abnormal early IRC study, showing either reflux (two) or findings suggestive of pathological renal parenchyma (one).

CONCLUSIONS

In addition to the well-established role of renal scintigraphy in excluding obstruction of the collecting system, early IRC is characterized by high sensitivity and accurate negative predictive value for detecting VUR. It can therefore be used to screen adults presenting with acute pyelonephritis for the presence of VUR. Patients with an abnormal IRC require follow-up VCUG after complete recovery, while those with a negative study may be managed expectantly, with no further radiological evaluation. This proposed strategy may avoid up to half of the delayed VCUG studies, preclude the related inconvenience, and substantially reduce the costs.

Renal scintigraphy in children with urinary tract infections

Background/Aim. To determine the incidence of abnormal Technetium Tc 99m Dimercaptosuccinic Acid (Tc99m DMSA) renal scintigraphy findings in the children with urinary tract infection (UTI), and to evaluate the difference between the children with UTI and vesico-ureteral reflux (VUR), and the children with UTI without VUR. Methods. Tc99m DMSA renal scintigraphy was performed in 170 children with UTI, mean age 7.07 years (1 month to 14 years, 137 were girls and 33 were boys). In 88 of the children, VUR was proved by micturating cystouretherography (MCU), while in 82 VUR could not be detected by MCU. VUR was graded in accordance with MCU recommended by the international study of VUR. In 13 of the children the grade of VUR was grade I, in 30 was grade II, in 23 grade III, in 17 grade IV, while the grade V was in 5 of the children. Findings of Tc99m DMSA renal scintigraphy were classified as: 1 - normal, 2 - probably normal, 3 - equivocal, 4 - probably abnormal, and 5 - abnormal. The degree of the significance of the difference of the findings was estimated using ?2, taking p < 0.01 as the limit of statistical significance. Results. Of the total number of 170 studied children, the abnormal findings were detected in 30% (51/170), normal findings in 62% (106/170), and equivocal in 8% (13/170). In the children with UTI and VUR, the incidence of abnormal findings was 49% (43/88), of normal 43% (38/88), and of equivocal findings 8% (7/88). All the children with VUR grade V had the abnormal findings (the incidence of the abnormal findings was 100%). In the children with VUR grade IV, the abnormal findings were 71%. In the children with VUR grade I, 77% of the findings were normal, in the children with VUR grade II, 53% of the findings were normal and in the children with VUR grade III, 30% of the findings of renal scintigraphy were normal. In the children with UTI without VUR, the incidence of abnormal findings was 10% (8/82), of normal findings 83% (68/82), and of equivocal findings 7% (6/82). The incidence of abnormal findings was significantly higher in the children with UTI and VUR than in those with UTI without VUR (p < 0.01). Also, the incidence of the abnormal findings was higher in the children with VUR grades IV and V than in the children with VUR grade I (p < 0.01). Conclusion. DMSA renal scintigraphy in the children with ITU revealed the abnormal findings in 30% of the cases. The incidence of the abnormal findings was significantly higher when VUR was present, as well as if the grade of VUR was higher. Our results confirmed that Tc99m DMSA renal scintigraphy was a very important technique in the evaluation of the children with ITU.

DMSA study performed during febrile urinary tract infection: a predictor of patient outcome?

Technetium-99m dimercaptosuccinic acid (DMSA) study has been advocated as a method for the assessment of renal sequelae after acute febrile urinary tract infection (UTI). However, it is not known whether DMSA scintigraphy performed during acute UTI has any prognostic value for outcome assessment. The objective of this study was to evaluate the usefulness of DMSA scintigraphy performed during UTI as a predictor of patient outcome, to identify children at risk of events [vesico-ureteral reflux (VUR) or recurrent UTI] that may lead to the development of progressive renal damage. One hundred and fifty-two children (including 78 girls) with a mean age of 20 months (range 1 month to 12 years) with first febrile UTI were evaluated by DMSA scintigraphy during acute UTI. After acute UTI, children were explored by voiding cysto-urethrography. Children who presented an abnormal DMSA study, or a normal DMSA study but VUR or recurrent UTI, underwent a DMSA control study 6 months after UTI. Children with VUR were followed up by direct radionuclide cystography. DMSA scintigraphy performed during acute UTI was normal in 112 children (74%). In 95 of these children, follow-up DMSA scintigraphy was not performed owing to a good clinical outcome. In the remaining 17 children, follow-up scintigraphy was normal. Forty children (26%) presented abnormal DMSA study during acute UTI. Twenty-five of them presented a normal follow-up DMSA, and 15 presented cortical lesions. Children with abnormal DMSA had a higher frequency of VUR than children with normal DMSA (48% vs 12%). It is concluded that children with normal DMSA during acute UTI have a low risk of renal damage. Children with normal follow-up DMSA and low-grade VUR have more frequent spontaneous resolution of VUR.

Guidelines for direct radionuclide cystography in children

These guidelines, which summarise the views of the Paediatric Committee of the European Association of Nuclear Medicine, provide a framework which may prove helpful to nuclear medicine teams in daily practice. They contain information on the indications, acquisition, processing and interpretation of direct radioisotope cystography in children. The guidelines should be taken in the context of "good practice" and any local/national rules which apply to nuclear medicine examinations.

Power Doppler sonography versus Tc-99m DMSA scintigraphy for diagnosing acute pyelonephritis in children: are these two methods comparable?

PURPOSE This study assessed the role of renal power Doppler ultrasonography (PDU) to identify acute pyelonephritis (APN) and to determine whether PDU can replace Tc-99m DMSA renal scintigraphy in the diagnosis of APN in children. METHODS A prospective study was conducted in 40 infants and young children (78 kidneys were evaluated) with a mean age of 25.9 months (range, 1 to 68 months) who were hospitalized with a first episode of high fever and bacteruria, possibly APN. All children were examined by PDU and Tc-99m DMSA within the first 3 days after admission. Patients with congenital abnormalities, hydronephrosis, and urinary reflux were excluded. RESULTS Twenty-seven of the 78 kidneys appeared abnormal on Tc-99m DMSA, and 20 of them were abnormal on PDU. Fifty-one of 78 kidneys were normal on Tc-99m DMSA, and 3 of 51 appeared diseased on PDU. The accuracy of PDU was 87%, sensitivity was 74%, and specificity was 94%. The positive predictive and negative predictive values were both 87%. When considering the numbers of lesions in 27 kidneys with positive Tc-99m DMSA studies (38 lesions), PDU did not disclose 16 lesions (false-negative results). Thus, the sensitivity of PDU for diagnosing lesions of APN decreased to 58%. CONCLUSIONS A positive PDU finding should obviate the use of Tc-99m DMSA in patients thought to have possible APN. However, because of a large number of false-negative results (26%) and underestimation of the number of pyelonephritic lesions (low sensitivity of 58%), PDU cannot replace Tc-99m DMSA in the diagnosis of APN in children.

[Power Doppler sonography and acute pyelonephritis in children: comparison with Tc-DMSA scintigraphy]

Acute pyelonephritis is a common infection in children. The clinical and biological diagnosis is still sometimes difficult. For most authors, Technecium 99m dimercaptosuccinic acid scintigraphy is considered as the gold standard tool for diagnosis but it is invasive and expensive. The aim of our study was to compare the sensitivity and the specificity of B-mode sonography and power doppler to DMSA-Tc scintigraphy in acute pyelonephritis.

PATIENTS AND METHODS

Forty-nine children were enrolled in this study with suspicion of pyelonephritis. All infants underwent doppler sonography and scintigraphy within 48 hours after their hospitalization. Doppler sonography criteria were increased kidney size, thickness of sinus wall, vascular defect, and various echogenicity of the kidneys (focal or diffuse hyperechogenicity or focal hypoechogenicity).

RESULTS

Among 28 children with a positive scintigraphy, 15 had a positive doppler sonography (sensitivity 54%) and 13 had a negative doppler sonography. Among 21 children with a negative scintigraphy, 20 had a negative doppler sonography (specificity 95%) and one had a positive doppler sonography.

CONCLUSION

In clinically suspected acute pyelonephritis, doppler sonography has a high specificity. A positive doppler sonography should avoid the use of scintigraphy.

Follow-up of acute pyelonephritis in children by Tc-99m DMSA scintigraphy: quantitative and qualitative assessment

PURPOSE

The author's goal was to create a system to identify children at risk for development of progressive renal damage.

METHODS

Thirty-four children were examined with Tc-99m DMSA scintigraphy in the acute stage of an initial episode of pyelonephritis, after 6 months, and again after 1 year. The scintigraphic findings were correlated with clinical and laboratory data.

RESULTS

All children had parenchymal defects in the acute stage: 93% of the kidneys and 85% bilaterally. After 6 months, the defects had diminished or disappeared in 66% of the kidneys. New defects appeared in 22%. At 1 year, no further improvement was seen in the kidneys, with an improved or unchanged pattern at 6 months. New defects appeared in 34%. Mean kidney activity uptake expressed as the percentage of administered dose (KU/AD), was low in the acute stage, increased at 6 months, with no further significant increase at 1 year. Eighty-three percent of children with urine cultures growing > or = 104 bacteria/ml at follow-up had decreased KU/AD values, whereas all children with urine cultures growing < 104 bacteria/ml had increased KU/AD values.

CONCLUSIONS

Quantitative assessment increases the sensitivity of Tc-99m DMSA scintigraphy. Follow-up with this method makes it possible to identify the children with decreasing renal tubular function who may be at risk for progressive renal damage. Moderate bacteruria of 104 bacteria/ml urine is associated with deterioration of renal tubular function.

Surgical correction of vesicoureteral reflux: 5-year follow-up with 99Tcm-DMSA scintigraphy

AIM

To evaluate kidney function before and after surgical correction of vesicoureteral reflux. The long-term effect was measured with quantitative nephro-scintigraphy using 99Tcm labelled dimercaptosuccinic acid (99Tcm-DMSA).

METHODS

Forty-five children with a history of urinary tract infections due to vesicoureteral reflux (VUR) were studied. VUR grade was determined with contrast voiding cystourethrography. Planar scintigraphy was performed with 99Tcm-DMSA and uptake measured as a percentage of injected dose. Kidney function was evaluated at baseline and 5 years after corrective surgery.

RESULTS

Three months after surgery, persistent mild reflux was found in eight of 76 treated renal units. Kidney uptake at 5-year follow-up was unchanged in the majority of children, indicating preservation of renal function found at baseline. The split renal function showed an excellent correlation (r = 0.99) between baseline and follow-up studies (regression slope 1.01). Percentage uptake had a regression slope of 0.89 significantly different from unity (P<0.05). Empirical kidney-depth correction techniques were compared. The scintigraphic pattern worsened in six kidneys, indicative of increased scarring in a minority of children.

CONCLUSION

Planar nephro-scintigraphy with 99Tcm-DMSA was well tolerated in our paediatric population, and appeared appropriate to evaluate kidney function in time. After surgical correction of VUR, the baseline function was maintained in 94% of kidneys.

Direct comparison of radiology and nuclear medicine cystograms in young infants with vesico-ureteric reflux

OBJECTIVE

To determine the sensitivity of the direct radionuclide cystogram (DRC) in detecting vesico-ureteric reflux compared with the micturating cysto-urethrogram (MCU) in the same initial setting, in infants younger than one year.

PATIENTS AND METHODS

The results from the dual cystograms of 62 refluxing infants < 1 year old (mean 0.58) were compared. Results from same-day renal scintigraphy with dimercaptosuccinic acid (DMSA) in 60 of the 62 infants were also compared with the reflux grades.

RESULTS

Reflux was detected in 105 units, 96 detected on the DRC and 47 on the MCU, representing a sensitivity of 91% and 45%, respectively. The DRC missed half of grade 1, 20% of grade 2 and 6% of grade 3 reflux. Reflux at low bladder filling rates (DRC) represented 40% of all reflux units, and a half (52%) of scarred renal units detected by DMSA scintigraphy.

CONCLUSIONS

In young infants the MCU may fail to detect significant reflux and the DRC may fail to detect the lesser grades. The combination of both cystograms in the initial investigation of reflux provides more comprehensive information.

Atlas on acute pyelonephritis in children

The authors describe various patterns of Tc-99m DMSA images that correspond to a diagnosis of acute pyelonephritis. Only those children with complete scintigraphic healing or considerable improvement after 6 months have been considered.

Consensus on renal cortical scintigraphy in children with urinary tract infection. Scientific Committee of Radionuclides in Nephrourology

A questionnaire related to cortical scintigraphy in children with urinary tract infection was submitted to 30 experts. A wide consensus was reached on several issues related to planar images: 99mTc dimercapto succinic acid (DMSA) appears as the most appropriate tracer for renal imaging; dynamic tracers are considered to be inferior, in particular 99mTc diethylenetriaminepentaacetate, which is not recommended. The general opinion is that DMSA scintigraphy is not feasible with a minimal dose below 15 MBq, whereas the maximum dose should not be higher than 110 MBq. The dose schedule generally is based on body surface area, and sedation is only exceptionally given to children. Images are obtained 2 to 3 hours after injection, preferably with high resolution collimators; pinhole images are used by only half of the experts. Posterior and posterior oblique views are used by most of the experts, and the posterior view is acquired in supine positions. At least 200.000 kcounts or 5 minute acquisition is required for nonzoomed images. As a quality control, experts check the presence of blurred or double outlines on the DMSA images. Color images are not used and experts report on film or directly on the computer screen. As far as normal DMSA images are concerned, most experts agree on several normal variants. Hydronephrosis is not a contraindication for DMSA scintigraphy but constitutes a pitfall. Differential renal function generally is measured, but no consensus is reached whether or not background should be subtracted. Most of the experts consider 45% as the lowest normal value. A consensus is reached on some scintigraphic aspects that are likely to improve and on some others that probably represent persistent sequelae. There is a wide consensus for the systematic use of DMSA scintigraphy for detection of renal sequelae, whereas only 58% of the experts are systematically performing this examination during the acute phase of infection.

The office management of recurrent urinary tract infection and vesicoureteral reflux in children

Recurrent urinary tract infections (UTIs) and vesicoureteral reflux are common diagnosis' in infants and children who are referred to a urologist. Recurrent UTIs in these patients can be challenging, especially when radiographic evaluation reveals no structural abnormality. Prophylaxis and correction of voiding and bowel dysfunction are important treatment strategies. Febrile UTIs are commonly associated with reflux and should be treated aggressively to avoid renal scarring and its sequelae. Based on a comprehensive survey of the literature, long-term treatment strategies for children with reflux are now available.

A study of reflux in patients with an ileal orthotopic bladder

OBJECTIVE

To determine whether there is vesico-ureteric reflux during voiding in patients who had undergone an ileal bladder substitution after cystectomy.

PATIENTS AND METHODS

The study comprised 15 patients (13 men and two women) who had undergone radical cystectomy and construction of a Studer ileal neobladder. At 1-24 months (median 4) after the operation indirect radionuclide cystography (IRC) was performed after isotopic renography (using 99m-technetium mercapto-acetyltriglycine) and voiding cysto-urethrography (VCUG).

RESULTS

None of the patients had reflux during voiding, either on IRC or on VCUG. Renal function and morphology remained stable in all patients. Despite bacteriuria occurring in four patients, no episode of pyelonephritis was reported.

CONCLUSION

There was no vesico-ureteric reflux during voiding in patients with a Studer ileal bladder substitution. However, long-term follow-up is needed to finally determine whether an antirefluxive ureteric implantation is required to protect the upper urinary tract in patients with ileal low-pressure bladder substitutions.

Renal SPECT with Tc-99m DMSA in children with upper urinary tract infections using a triple-headed gamma camera

Renal cortical scintigraphy with Tc-99m DMSA provides an excellent imaging modality for the assessment of cortical damage secondary to upper urinary tract infection (UTI).

METHODS

The authors evaluated 48 children with UTI, 12 of whom had a history of vescico-ureteral reflux (from first of fourth degree), by planar scintigraphy and SPECT using a triple-headed gamma camera equipped with parallel-hole, high-resolution collimators.

RESULTS

SPECT images yielded positive findings in 36 kidneys, whereas planar scans yielded positive findings in 18 kidneys. The total number of lesions detected by SPECT was 51, whereas the number found with the planar technique was 23.

CONCLUSION

This study demonstrates the superiority of SPECT scanning in detecting kidney lesions in children with UTI.

Pediatric uroradiology update

The present focus in pediatric uroradiology is a healthy reappraisal of the indications for and clinical use of the numerous modalities available for evaluating the child who has a urinary tract infection. The purpose of this article is to update the urologist with respect to the problems that are involved in discussing the diagnosis and imaging of the pediatric urinary tract infection.

Kidney swelling. Findings on DMSA scintigraphy

OBJECTIVE

To develop criteria identifying swollen kidneys on dimercaptosuccinic acid (DMSA) renal scintigraphy in acute pyelonephritis with regard to the DMSA distribution pattern, kidney functional size, and radioactive uptake.

SUBJECTS AND METHODS

Thirty-eight children aged 15 days to 7 years with known pyelonephritis were examined with DMSA renal scintigraphy. All children were observed 2 or 3 times. In total, 94 scintigrams were evaluated. Qualitative and quantitative criteria for swelling were defined.

RESULTS

Thirty-one observed kidneys satisfied the criteria of swelling. Quantitatively, kidney length and width/length were greater in swollen kidneys. Kidney uptake in percent of injected dose and kidney uptake/background were lower in swollen kidneys. Qualitatively, focal radioactive uptake defects known from a previous examination were sometimes obscured by swelling, and reappeared at follow-up. In 5 children with signs of swelling on repeat imaging, scintigraphy reinfection at the time of swelling was verified.

CONCLUSIONS

Swollen kidneys may be the only sign of acute pyelonephritis on DMSA scintigraphy and swelling may obscure focal radioactive uptake defects. Measurement of kidney size and radioactive uptake can help identify swollen kidneys at DMSA scintigraphy and disclose acute pyelonephritis in the absence of overt clinical symptoms.

Febrile urinary tract infection in children: Role of 99MTc-dimercaptosuccinic acid (DMSA) scan and other imaging techniques

Fifty children (37 females and 13 males) with first febrile urinary tract infections were studied to assess the value of 99MTc-dimercaptosuccinic acid (DMSA) scan in detecting inflammatory changes of acute pyelonephritis (APN). These findings were compared with renal ultrasonography (US). We also evaluated the reliability of clinical and laboratory observations in diagnosing acute pyelonephritis (APN). All children had micturating cystourethrography (MCUG). DMSA-documented acute pyelonephritis was present in 29 (58%) patients. Only four children (8%) demonstrated changes suggestive of APN on renal ultrasonography. Vesicoureteric reflux (VUR) was documented in 17 (47%) of the total group and in 13 (45%) of those with abnormal DMSA scan. Follow-up DMSA scan in 15 children with initial abnormal findings showed complete recovery in seven (47%). Our data have shown that DMSA renal scan is the most useful investigational procedure in children with febrile UTI. The diagnosis of APN, depending on clinical and laboratory data, is unreliable. Renal US alone can miss serious renal defects. MCUG remains the most sensitive procedure to detect VUR and it should be performed in all children with UTI and abbormal DMSA scan. Early detection of acute pyelonephritis allows the prompt introduction of antimicrobial agents in those children and can prevent or decrease renal damage and its complications.

Where are we with nuclear medicine in pediatrics?

The practice of nuclear medicine in children is different from that in adults. Technical considerations including immobilization, dosing of radiopharmaceuticals, and instrumentation are of major importance. Image magnification and the capability to perform single-photon emission tomography are essential to performing state of the art pediatric nuclear medicine. New advances in instrumentation with multiple detector imaging, the possibility of clinical positron emission tomography imaging in children, and new radiopharmaceuticals will further enhance pediatric scintigraphic imaging. This review highlights advances in pediatric nuclear medicine and discusses selected clinical problems.

Uroradiologic evaluation of children with urinary tract infection: are both ultrasonograpy and renal cortical scintigraphy necessary?

OBJECTIVE

To compare the findings of renal ultrasonography (RUS), 99mTc glucoheptonate renal scan (GHS), and voiding cystourethrography (VCUG) in children with urinary tract infection.

DESIGN

Prospective, masked, clinical study.

SETTING

Single center, multidisciplinary, inpatients.

PATIENTS

Consecutive cases (N = 50) of children aged 2 months to 15 years (8 boys, 42 girls) with pyelonephritis in whom uroradiologic investigation was indicated.

MEASUREMENTS AND MAIN RESULTS

All patients underwent GHS, 48 had RUS, and 2 had intravenous pyelography. All but one of the patients had a VCUG. Fifteen children were found to have vesicoureteral reflux (6 unilaterally, 9 bilaterally). Of 96 kidneys evaluated by both GHS and RUS, 53 were abnormal by GHS versus 28 by RUS (p < 0.001). Findings of both GHS and US were normal in 36 kidneys and abnormal in 21 kidneys. In 32 kidneys only GHS showed abnormalities. In 7 kidneys only RUS showed abnormalities; 5 of them had mild to moderate pelvic dilation caused by reflux, which was confirmed in all 5 by VCUG. The VCUG demonstrated reflux in another four units with normal GHS and RUS findings. All combined, GHS and VCUG detected 62 of 64 abnormal renal units (96.9%). In the other two cases, RUS showed only focal hyperechogenicity of questionable importance.

CONCLUSION

In the event that one elects to use GHS for the uroradiologic evaluation of children with urinary tract infection, it can be supplemented by VCUG alone, and RUS can be saved for special cases.

Correlative imaging of the kidney

The proliferation of imaging methods for the kidney and urinary tract, combined with advances in technology and the introduction of new techniques, has created uncertainty in selecting the most efficient method for evaluating many problems encountered in clinical medicine. The main advantage of nuclear medicine lies in demonstrating the pathophysiology involved. Recent developments in Doppler ultrasound and magnetic resonance imaging with different pulse sequences and paramagnetic contrast agents also have shown promise for imaging physiological processes. However, there is little literature to support their advantage over nuclear medicine procedures in many common clinical situations. The complementary nature of nuclear medicine studies in the imaging evaluation of hydronephrosis, renal artery stenosis, flank pain, renal mass, pyelonephritis, and the transplant kidney is reviewed.