Renal cortical scintigraphy and diuresis renography in infants and children.

Renal scintigraphy is performed frequently in infants and children. Renal cortical scintigraphy using 99mTc dimercaptosuccinic acid is predominantly performed to assess the renal sequelae of urinary tract infection. It is most commonly performed for the evaluation of chronic renal scars, although it is also undertaken in the assessment of acute pyelonephritis. Diuresis renography using 99mTc mercaptoacetyltriglycine is of great use in the evaluation of renal tract obstruction, which may occur at a variety of levels, but most commonly occurs at the ureteropelvic junction. Consensus statements have been formulated in an attempt to standardize methods of performing these investigations. However, several areas of controversy exist in the performance of these studies, and these are outlined. Radionuclide cystography and renal function estimation using clearance calculations are not covered in this article.

Scintigraphic features of primary sacral tumors.

The bone scan features of different types of sacral tumors in 16 patients were assessed. Four out of five patients with chordoma, the most common sacral tumor, demonstrated either reduced uptake or normal distribution of isotope at the site of this midline tumor. Plasmacytoma, which is not usually central, also caused reduced uptake on the bone scan. Ewing's sarcoma gave no consistent pattern. All other tumors caused increased uptake except for one unusual case of osteogenic sarcoma. Bone scintigraphy can be very useful in the assessment of sacral tumors. A midline sacral tumor that is cold on the bone scan is very likely to be a chordoma.

Diuretic renography with the addition of quantitative gravity-assisted drainage in infants and children.

UNLABELLED: The aim of this study was to evaluate the use of quantitative gravity-assisted drainage (GAD) using >50% residual activity as an indicator to confirm obstruction in diuretic renography in the investigation of hydronephrosis and hydroureteronephrosis in infants and children. This was evaluated in 2 groups: furosemide clearance half-time (t 1/2) > 20 min (obstructed range) and t 1/2 = 10-20 min (indeterminate range). METHODS: Two hundred children (155 boys, 45 girls; age range, 2 d to 16 y; median age, 26 wk) were studied over a 2-y period. One hundred thirty-five F+20 (diuretic given 20 min after radiopharmaceutical) and 65 F+0 (simultaneous administration of diuretic and radiopharmaceutical) studies were performed with intravenous administration of 99mTc-mercaptoacetyltriglycine (MAG3) and furosemide. At the end of the 20-min diuretic phase, a 5-min post-GAD image was obtained, and the percentage of residual activity was calculated by comparison with the last 5 min of the diuretic phase. All patients were monitored for 6-12 mo, and the final diagnoses were based on either surgical findings or conservative management with follow-up sonography or 99mTc-MAG3 studies. Results of the diuretic renography using quantitative GAD were then compared with the final diagnoses. RESULTS: A renal unit was defined as a kidney and its ureter. In the 200 patients studied, 256 hydronephrotic renal units were analyzed: 10 units showed no function, 1 unit showed poor function, 131 units had t 1/2 < 10 min, 62 units had t 1/2 > 20 min, and 52 units had t 1/2 = 10-20 min. Of the 131 renal units with t 1/2 < 10 min, there was only 1 case of obstruction. Using GAD > 50% residual activity for the diagnosis of obstruction in 62 renal units with t 1/2 > 20 min, the sensitivity was 88.4%, the specificity was 73.7%, and the accuracy was 83.9%. Similarly, using GAD > 50% residual activity for the diagnosis of obstruction in 52 units with t 1/2 = 10-20 min, the sensitivity was 100%, the specificity was 79.5%, and the accuracy was 82.7%. CONCLUSION: The quantitation of GAD > 50% residual activity in diuretic renography can help to differentiate between obstruction and nonobstruction in renal units with t 1/2 > 20 min and t 1/2 = 10-20 min. The quantitation of GAD when t 1/2 < 10 min is not useful because obstruction has already been excluded.

Utility of technetium-99m-MAG3 diuretic renography in the neonatal period.

UNLABELLED: Diuretic renography performed in the neonatal period has been reported to be unreliable in diagnosing obstruction. METHODS: The scans of 27 neonates (age up to 28 days; mean 17 days) with a total of 53 renal units were reviewed; a renal unit being defined as comprising a kidney and its ureter. All were referred following perinatal ultrasound diagnosis of hydronephrosis or hydroureteronephrosis. The neonates had standard diuretic renography using MAG3 with a frusemide dose of 1 mg/kg followed by another image obtained after gravity-assisted drainage. RESULTS: There were 17 normal undilated renal units showing excellent diuretic responses with clearance half-times of 0.6-7.7 min. Eighteen renal units were diagnosed as having pelvi-ureteric junction (PUJ) obstruction, with surgical confirmation in all. Eight were diagnosed as unobstructed and of these seven were confirmed nonobstructed by serial imaging using ultrasound and MAG3, but one subsequently had pyeloplasty performed for PUJ obstruction. One unit was indeterminate for PUJ obstruction but had good clearance with gravity-assisted drainage and was shown to be unobstructed on repeat studies. Of nine units diagnosed as having vesico-ureteric junction (VUJ) obstruction, eight had surgical confirmation and one remains of uncertain final diagnosis. Co-existing VUJ obstruction could not be diagnosed in two units with PUJ obstruction because of insufficient radiotracer drainage through the tight stenosis into the ureter. CONCLUSION: An adequate diuretic response is present in the neonatal period using MAG3 and this allows for reliable diagnosis of obstruction. An unobstructed or indeterminate result necessitates follow-up imaging to ensure obstruction does not develop. Co-existing VUJ obstruction may be missed in a scan showing PUJ obstruction.

F+0 diuresis renography in infants and children.

UNLABELLED: The purpose of this study was to evaluate the feasibility of modifying diuresis renography by the simultaneous administration of 99mTc-mercaptoacetyltriglycine (MAG3) and furosemide in the investigation of hydronephrosis and hydroureteronephrosis in infants and children. Two parameters were assessed: the diuretic response in normal kidneys and the ability of the F+0 study to differentiate between renal obstruction and nonobstruction and to identify the level of obstruction in cases of renal obstruction. METHODS: Seventy-two patients (48 males, 24 females; age 2 d to 7 y; median age 6 wk) with sonographic diagnoses of hydronephrosis or hydroureteronephrosis were reviewed prospectively over a 3-y period. All patients had prior sonographic studies and micturating cystourethrography. Bladder catheterization was not routinely performed and was undertaken only if the child had suspected vesicoureteric junction (VUJ) obstruction or grade II or more vesicoureteric reflux. A weight-adjusted dose of 99mTc-MAG3 (maximum 200 MBq, minimum 20 MBq) and 1 mg/kg of furosemide (maximum 40 mg) were administered intravenously at the same time. Posterior imaging of the kidneys and bladder was performed for 20 min and followed by gravity-assisted drainage or imaging after voiding. All patients were followed-up for 6-12 mo, and the final diagnoses were based on either surgery or conservative management with repeated sonography or follow-up 99mTc-MAG3 studies (or both). The results of the F+0 diuresis renography were then compared with the final diagnoses. RESULTS: A renal unit was defined as a kidney and its ureter. There were 151 renal units with 1 patient having bilateral duplex kidneys, 6 patients having unilateral duplex kidneys and 1 patient having a solitary kidney. Fifty-five normal renal units and 96 abnormal renal units on the basis of sonographic findings were assessed. The furosemide clearance half-time for the 55 normal renal units was 1.3-6.3 min (mean 3.8 min). Of the 96 abnormal renal units, 53 were classified as nonobstructed and 43 were classified as obstructed. Of the 53 renal units classified as nonobstructed, there were 48 true-negative studies and 5 false-negative studies; of the 43 renal units classified as obstructed, there were 40 true-positive studies and 3 false-positive studies. The sensitivity was 88.9%, specificity was 94.1% and accuracy was 91.7%. The level of obstruction, either pelviureteric junction or VUJ, was also correctly identified. CONCLUSION: F+0 diuresis renography shows excellent diuretic responses in normal kidneys and is a valid method for the investigation of hydronephrosis and hydroureteronephrosis in infants and children.

Pediatric solid tumors: evaluation by gallium-67 SPECT studies.

A retrospective review of 37 children with a variety of solid tumors who underwent 60 67Ga single-photon emission computed tomographic (SPECT) studies was performed. These studies were correlated with clinical and radiological findings and, where possible, histopathologic confirmation. In all studies, SPECT gave better definition and better anatomic localization of disease sites than obtained with planar views. SPECT detected more lesions in the head and neck (planar 16, SPECT 19), chest (planar 39, SPECT 45), and abdomen (planar 22, SPECT 24). In six of 20 patients scanned following chemotherapy, SPECT was useful in demonstrating that tracer accumulation in a normally located and shaped thymus indicated uptake resulting from thymic regeneration rather than tumor recurrence. It is concluded that 67Ga SPECT studies are very useful in the pediatric population, where perhaps because of their small size, interpretation of standard planar views may be difficult.

Technetium-99m dimercaptosuccinic acid scintigraphy studies of renal cortical scarring and renal length.

UNLABELLED: The aims of this study were to validate 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy appearances with histopathological features of scarring; to evaluate the sensitivity and specificity of 99mTc-DMSA and ultrasound for the detection of renal scarring; to compare planar, pinhole and SPECT techniques when using 99mTc-DMSA; and to compare 99mTc-DMSA and ultrasound renal length measurement. METHODS: Reflux nephropathy was induced in large white pigs using established methods. To ensure that the abnormalities detected were scars and not inflammatory changes, the pigs were not studied until 3 mo after the treated episode of acute pyelonephritis confirmed by 99mTc-DMSA. RESULTS: Twenty pigs were enrolled in the study. Eleven reached the end point, but only nine pigs (18 kidneys) were available for analysis. Thirty-four scars were identified pathologically; 24 were present macroscopically and a further 10 were seen only on microscopy. Technetium-99m-DMSA abnormalities correlated with scars histopathologically with an accuracy of 92% versus that of ultrasound, 75% (p < 0.001). Technetium-99m-DMSA more accurately identified scarring with a higher sensitivity (76% versus 29%) and specificity (98% versus 92%) than ultrasound. On the 99mTc-DMSA study, pinhole imaging had the highest accuracy (92%) when compared with planar (90%) and SPECT (87%) data. These differences were not statistically significant. Renal lengths as measured on 99mTc-DMSA more closely correlated with length measurement at pathological examination than ultrasound. Technetium-99m-DMSA measurement was, on average, 6% higher than pathology, and ultrasound was, on average, 22% lower. CONCLUSION: Technetium-99m-DMSA appears to be the preferred method for the detection of renal cortical scarring and accurate renal length measurement when compared with ultrasound examination.

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.

An unusual site of heterotopic calcification.

Heterotopic calcification may occur following paralysis from spinal cord injury, most commonly affecting the hips. This case demonstrates a bone scan on a T5 paraplegic patient showing an unusual site of heterotopic calcification in the paravertebral musculature in addition to the hip regions. Subsequent CT scanning confirmed the presence of calcification in the erector spinae musculature.

The interrenicular septum. A normal anatomical variant seen on DMSA SPECT.

SPECT imaging has been shown to identify additional defects when applied to Tc-99m DMSA scintigraphy. However, the nature of these defects is uncertain. They may be because of small scars or anatomical variants. The interrenicular septum (IRS) is a normal finding that may mimic a scar on ultrasound examination or tomography. In this study, it was found that the IRS may be identified on Tc-99m DMSA SPECT and that it was present in 32% of patients. Its characteristic appearance is a linear area of absent tracer uptake extending from the renal hilum into the parenchyma, usually anterosuperiorly. The preservation of renal cortical uptake differentiates it from a scar, which results in a defect in the rim of cortical Tc-99m DMSA accumulation.

Focal defects on liver scintigraphy due to right ventricular failure.

A case of focal defects seen on liver scintigraphy on the basis of right ventricular failure is presented. The pattern bore a striking similarity to that seen in hepatic metastases.

Diuresis renography. The need for an additional view after gravity-assisted drainage.

The role of diuresis renography (DR) in the evaluation of pelvi-ureteric junction obstruction is well established. However, problems may be encountered when applying this technique to patients after pyeloplasty because of the role of gravity-assisted drainage (GAD) in this post-operative group. Twenty-three radionuclide studies that were performed in 21 children were reviewed. All children underwent standard DR and all then had an additional view performed after GAD. In 12 children evaluated in a preoperative assessment for possible obstruction, 5 were obstructed on both DR and after GAD, 1 was equivocal on DR but drained after GAD, and 6 were not obstructed in either part of the study. In 11 children assessed after pyeloplasty, 5 were obstructed on DR but not obstructed on GAD, 3 were not obstructed in both studies, 1 was obstructed in both, and 2 were equivocal on DR but not obstructed after GAD. It can be concluded that when assessing patients, particularly those who have undergone pyeloplasty, DR should be supplemented with an additional view acquired after gravity-assisted drainage.

Determination of the normal range of furosemide half-clearance times when using Tc-99m MAG3.

In radionuclide diuresis renography, furosemide half-clearance times have been established using Tc-99m DTPA but have not been verified when Tc-99m MAG3 is used. One hundred and six consecutive diuretic renograms using Tc-99m MAG3 for the evaluation of unilateral renal abnormalities were assessed. The furosemide half-clearance times of the normal kidneys were all less than 9.8 minutes, with a mean of 3.4 minutes. In 18 patients, the half-clearance times of the normal kidney were artificially prolonged because urine had drained before the administration of the diuretic. The normal furosemide half-clearance time values obtained using Tc-99m MAG3 were found to be similar to those established for Tc-99m DTPA. Prolonged half-clearance times of Tc-99m MAG3 must be confirmed by visual evidence of obstruction.

Intense muscle uptake of Tc-99m MDP and Ga-67 citrate in massive rhabdomyolysis.

A 6-year-old boy had an Addisonian crisis with hyponatremic shock and required resuscitation after cardiac arrest. Severe renal failure necessitated continuous dialysis. Rhabdomyolysis was identified because of myoglobinuria and gross elevation of creatinine kinase. In the course of his treatment, bone infection was suspected. A bone scan with Tc-99m MDP showed intense uptake in numerous major muscle groups throughout the body in keeping with massive rhabdomyolysis. Similar gross muscle uptake of Ga-67 citrate was less expected. In an additional bone scan obtained 15 days later, the MDP uptake showed less intense accumulation.

The use of SPECT in the diagnosis of epiphyseal osteoid osteoma.

An osteoid osteoma, which rarely occurs in an intraepiphyseal site, was identified by SPECT imaging in the proximal tibial epiphysis of a boy who had lower back pain, which had not been explained prior investigations.

Nomograms of renal length in children obtained from DMSA scintigraphy.

The aim of this study was to establish nomograms of renal length in children comparing age, body weight, and height. Renal lengths were obtained from data derived from Tc-99m DMSA scintigraphy in 266 patients with 532 kidneys that appeared normal on DMSA studies. The children's ages ranged from 6 days to 19 years. Renal length appeared to have nonlinear relationships with patient weight and age, but was found to correlate linearly with patient height. On average, scintigraphic renal length exceeded sonographic renal length by approximately 1 cm. The most likely explanation for this is the effect of respiration causing renal motion during the acquisition of the scintigraphic images. It is hoped that the nomograms derived from these data will be of use in routine clinical practice for nuclear medicine departments performing DMSA scintigraphy in children.

Staging and managing lung tumors using F-18 FDG coincidence detection.

PURPOSE: Fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomographic (PET) imaging can be a vital tool in the evaluation and preoperative staging of pulmonary neoplasms. Imaging studies on the gamma camera using coincidence PET (co-PET) were introduced recently into clinical practice. This prospective study assessed the efficacy of co-PET for identifying primary tumors, mediastinal lymph node involvement, the presence of distant spread, the effect on disease staging, and influence on disease management. PATIENTS AND METHODS: Sixty consecutive patients with 61 lung tumors were enrolled in the study (36 men, 24 women; age range, 32-87 years; mean age, 67 years). Histopathologic confirmation was obtained in 58 patients (59 tumors). RESULTS: In assessments of a primary lesion to establish its malignant or benign nature, the sensitivity rate of co-PET was 96% (53 of 55 lesions), the specificity rate was 83% (5 of 6 lesions), and the accuracy rate was 95% (58 of 61 lesions). In the co-PET assessment of lymph node involvement in which histopathologic confirmation was obtained (n = 32), the sensitivity rate was 89% (8 of 9 lesions), the specificity rate was 91% (21 of 23 lesions), and the accuracy rate was 91% (29 of 32 lesions). Previously unknown distant metastases were correctly identified in eight patients, but five false-positive lesions were detected in the brain. Disease staging was correctly altered in 20 patients (33%), and disease management plans were changed in 20 patients (33%) based on the co-PET findings. Unnecessary surgery was obviated in six patients (10%). One patient was given the chance for curative treatment based on the findings of the co-PET study. CONCLUSION: The evaluation of patients with lung neoplasms using F-18 FDG coincidence detection appears to be reliable.

Serial bone scans in the assessment of response to therapy in advanced breast carcinoma.

Twenty-seven patients taking part in an advanced breast cancer trial in Australia and New Zealand were studied to assess the predictive value of serial bone scans as an indicator of response to therapy. The report of serial bone scans in 20 of the 27 patients correctly reflected the clinical outcome. Of the 20 patients, all had an initial subjective response and 15 had an objective response. Of the seven patients whose bone scan report did not reflect the clinical situation, five had increased uptake in known lesions and new lesions and one had increased uptake in known lesions only within six months of commencing therapy. These scan reports indicated progression of disease rather than a healing or "flare" response which was later proved to exist. One patient had clinical progression of bone metastases which was confirmed by x-ray but was not reflected in the bone scan until months later. Clinical progression of disease was accurately reflected in the bone scans of 11 of 12 patients. Recognition that a "'flare" effect in the first months of therapy may also cause new lesions to be seen should enhance the accuracy of bone scintigraphy.

Scintigraphic features of malignant epithelioid hemangioendothelioma.

The scintigraphic features of malignant epithelioid hemangioendothelioma of the liver have not been previously documented. In particular, there are no reports on the nature of gallium uptake in these rare tumors. The case reported is a young woman with primary hepatic epithelioid hemangioendothelioma. Metastatic disease in the skull was detected on a Tc-99m MDP bone scan. A Ga-67 study demonstrated that this tumor was not gallium avid.