Cortical Scintigraphy Research Articles

Vesicoureteral reflux: an accurate predictor of acute pyelonephritis in childhood urinary tract infection?

To determine the association between vesicoureteral reflux (VUR) and the presence of acute pyelonephritis in children with urinary tract infections. The authors studied 150 consecutive patients less than 5 years of age with their first proved urinary tract infection. All patients underwent renal cortical scintigraphy (with technetium-99m dimercaptosuccinic acid or Tc-99m gluconate) and voiding cystourethrography (VCUG) to identify the presence of cortical defects and VUR, respectively. Of 300 kidneys, 88 (29.3%) had a cortical defect at scintigraphy. Fifty-four of the 88 patients (61%) did not have VUR demonstrated at VCUG. Conversely, 72 of the 300 kidneys (24%) had VUR; of these, 38 (53%) had no cortical defect. The sensitivity of VCUG in helping predict a defect was 38.6%, and the specificity was 82.1%. VUR (as shown by VCUG) and renal cortical scintigraphic defects frequently occur independently of each other. Renal cortical scintigraphy may be a more accurate predictor of patients at risk for scarring.

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. (J P EDIATR 1994;124:17-20)

Scintigraphic evaluation of pediatric urinary tract infection

Scintigraphic evaluation of urinary tract infection, pyelonephritis, and renal scarring represents a significant portion of a clinical pediatric nuclear medicine practice. Renal scarring from recurring infection remains an important cause of end-stage renal disease and hypertension in the pediatric population. However, the clinical presentation in infants and young children is often elusive, and clinical diagnosis of upper tract involvement is frequently unreliable. As a result, diagnostic imaging has a critical role to play in the localization of infection to the lower or upper urinary tract. Radionuclide cystography and renal cortical imaging have become mainstays of this evaluation. Direct radionuclide cystography is the preferred cystographic screening technique, because it has lower radiation exposure and greater sensitivity for the detection of vesicoureteral reflux than either indirect radionuclide cystography or fluoroscopic contrast cystography. Renal cortical scintigraphy has become the standard for the detection of pyelonephritis and renal scarring. Correlation with histopathology has demonstrated a high degree of diagnostic accuracy. Acute pyelonephritis has been shown to be the necessary etiologic factor for the development of subsequent renal scarring, and the mechanism of renal injury in pyelonephritis has been extensively studied in experimental models. The ability of prompt and appropriate antibiotic therapy to dramatically reduce the incidence of subsequent scarring also has been conclusively demonstrated both clinically and in the experimental model. Vesicoureteral reflux was once thought to be a necessary prerequisite for the development of renal scarring. Although it is clear that the intrarenal reflux of infected urine will create pyelonephritis in the experimental model, the high incidence of pyelonephritis and subsequent scarring in the absence of demonstrable vesicoureteral reflux leaves the role of reflux in question. Although the role of vesicoureteral reflux is incompletely understood, its detection nevertheless remains a standard part of the patient's evaluation.

Comparison of planar and SPECT 99Tcm-DMSA scintigraphy for the detection of renal cortical defects in children

Renal cortical scintigraphy with 99Tcm-dimercaptosuccinic acid is an excellent imaging modality for the detection of renal cortical defects in children presenting with vesicoureteric reflux and urinary tract infections. Single photon emission computed tomography (SPECT) has proven increased sensitivity over planar scintigraphy for lesion detection in the heart, liver and brain. However, its role in the evaluation of renal cortical defects compared to planar scintigraphy has not been fully assessed. We wished to determine whether SPECT increases the sensitivity for detecting renal cortical defects in children compared to high-resolution planar scintigraphy. Forty-one children (90 renal units) with underlying vesicoureteric reflux and/or recently treated urinary tract infection (UTI) were evaluated. There was no statistically significant difference in the number of defects detected between a single-head SPECT system and high-resolution planar scintigraphy, 24 and 20, respectively (P = 0.54). There were four defects detected by SPECT not reported by planar scintigraphy; two of these were only seen retrospectively on planar scintigraphy. There were two children with renal cortical defects detected by SPECT and not by planar scintigraphy. All defects defected by planar scintigraphy were detected by SPECT. It is concluded that although the risk of missing renal cortical defects is low when using high-resolution, three-view planar scintigraphy, SPECT should be employed whenever feasible. Single photon emission computed tomography detected renal cortical defects in children not diagnosed by planar scintigraphy and hence patient management may be altered.

Dimercaptosuccinic Acid Renal Scintigraphy For The Evaluation of Pyelonephritis and Scarring: A Review of Experimental and Clinical Studies

Renal cortical scintigraphy has been reported to be useful in children for confirmation of the diagnosis of acute pyelonephritis. Subsequent experimental studies have demonstrated that dimercaptosuccinic acid (DMSA) scintigraphy, when compared directly with histopathology, is highly reliable for the detection and localization of parenchymal inflammatory changes associated with acute pyelonephritis. Recent clinical studies of acute pyelonephritis using DMSA scintigraphy reveal that the majority (50 to 91%) of children with febrile urinary tract infections have abnormal DMSA renal scan findings and that the majority of these children do not have demonstrable vesicoureteral reflux. However, when vesicoureteral reflux is present, renal cortical abnormalities are demonstrated by DMSA scintigraphy in 79 to 86% of the kidneys. In children with febrile urinary tract infections routine clinical and laboratory parameters are not reliable in the differentiation of acute pyelonephritis, documented by DMSA renal scan findings, from urinary tract infections without parenchymal involvement. Furthermore, the presence of P-fimbriated Escherichia coli associated with febrile urinary tract infections does not reliably predict those kidneys that have acute parenchymal inflammation demonstrated by DMSA renal scans.DMSA is also the isotope agent of choice for the detection of renal scarring. Clinical studies report greater sensitivity of DMSA renal scintigraphy for the detection of renal scarring when compared with the excretory urogram, particularly in infants and young children. In a recent prospective study of post-pyelonephritic renal scarring in children we found that acquired renal scarring only occurs in sites corresponding exactly to previous areas of acute pyelonephritis demonstrated by DMSA scintigraphy at the time of infection. Furthermore, once acute pyelonephritis occurs, ultimate renal scarring is independent of the presence or absence of vesicoureteral reflux. These findings provide convincing evidence that renal parenchymal infection, rather than vesicoureteral reflux, is the prerequisite for acquired (postnatal) renal scarring. Vesicoureteral reflux as a risk factor for acquired renal scarring is directly related to its role as a risk factor for acute pyelonephritis. We conclude that DMSA scintigraphy is a valid tool for confirming the diagnosis of acute pyelonephritis in children and for identifying kidneys at risk for subsequent renal scarring.

The Sensitivity of Renal Scintigraphy and Sonography in Detecting Nonobstructive Acute Pyelonephritis

Recently it has been demonstrated that any child with proved acute pyelonephritis may be at risk for parenchymal scarring, whether or not reflux is present. Since cortical renal scintigraphy has been shown to detect accurately renal inflammation, we compared cortical scintigraphy with renal sonography in 46 children with documented acute pyelonephritis to determine which modality is best to detect patients at risk for renal injury. Cortical scintigraphy was abnormal in 36 children (78%) and renal ultrasonography was abnormal in 5 (11%). Reflux was demonstrated in only 20 cases (43%). We conclude that cortical scintigraphy is the preferred imaging technique for diagnosing renal inflammation, and it should be used routinely in every child with suspected acute pyelonephritis. A new imaging protocol is proposed.

Renal cortical scintigraphy in the diagnosis of acute pyelonephritis

Comparative clinical studies have shown renal cortical scintigraphy, using technetium-99m (99mTc)-labeled glucoheptonate or dimercaptosuccinic acid (DMSA), to be significantly more sensitive than either intravenous pyelography or renal sonography in the diagnosis of acute pyelonephritis. However, due to uncertainties about the diagnostic accuracy of the clinical and laboratory parameters used in these studies, true sensitivity of renal cortical scintigraphy was unknown. Therefore, we evaluated the accuracy of [99mTc]DMSA scintigraphy in the diagnosis of experimentally induced acute pyelonephritis in piglets using strict histopathologic criteria as the standard of reference. The sensitivity and specificity of the DMSA scan for the diagnosis of acute pyelonephritis were 91% and 99%, respectively, with an overall 97% agreement between the scintigraphic and histopathologic findings. Based on the results of this experimental study, we used the [99mTc]DMSA scan as the standard of reference for the diagnosis of acute pyelonephritis, and conducted a prospective clinical study of 94 children hospitalized with the diagnosis of acute febrile urinary tract infection (UTI). The aims of this study were (1) to determine the relationship among vesicoureteral reflux, P-fimbriated Escherichia coli, acute pyelonephritis, and renal scarring, and (2) to evaluate the diagnostic reliability of the clinical and laboratory parameters commonly used in the diagnosis of acute pyelonephritis. We documented acute pyelonephritis in 62 (66%) of 94 patients. Vesicoureteral reflux was demonstrated in 29 (31%) of the total group and in only 23 (37%) of 62 patients with acute pyelonephritis. The prevalence of P-fimbriae in the E coli isolates was 64% in the patients with acute pyelonephritis and 78% in those with a normal DMSA scan. Even in patients without reflux, P-fimbriae were found in 71% of isolates from the patients with acute pyelonephritis and in 75% of those with a normal renal scan. Follow-up DMSA scans were obtained in 33 patients with acute pyelonephritis in 38 kidneys. We found complete resolution of the acute inflammatory changes in 58% of the involved kidneys and renal scarring in the remaining 42%, including 40% of the kidneys associated with reflux and 43% of those without reflux.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

The role of scintigraphy in urinary tract infection

There is controversy regarding the role of radiological imaging for urinary tract infection (UTI). The "gold standard" has been the intravenous pyelogram (IVP). Yet, the IVP has a very limited value with only about 25% of children with pyelonephritis demonstrating abnormalities. Ultrasound (US) has recently been advocated as a replacement for the poorly sensitive and poorly specific IVP. However, comparative studies between US and IVP indicate only an equivalent sensitivity and specificity. Cortical scintigraphy with Technetium-99m glucoheptonate (99mTc GH) or 99mTc dimercaptosuccinic acid (99mTc DMSA) has also been advocated as a means of differentiating parenchymal (pyelonephritis) from nonparenchymal (lower UTI) involvement in UTI. The clinical presentation may be misleading especially in the infant and child in whom an elevated temperature, flank pain, shaking chills, or an elevated sedimentation rate are often lacking. The clinician attempts to localize the site of infection for it has a direct bearing upon the therapy. A collecting system infection can often be eradicated with a single oral dose of an appropriate antibiotic, whereas renal parenchymal involvement requires IV therapy for an extended interval. Cortical scintigraphy can localize the site of infection with a high degree of accuracy. Recent studies report a sensitivity of 86% and specificity of 81% of pyelonephritis. This is in contrast to the IVP with a sensitivity of only 24% and US with a sensitivity of only 42%. The scintigraphic appearance of parenchymal infection of the kidney is a spectrum of minimal to gross defects reflecting the degree of histologic involvement that spans from a mild infection to frank abscess. Cortical scintigraphy can be used to monitor the evolution of scarring following infection. Cortical scintigraphy with 99mTc DMSA or 99mTc GH is the method of choice for the initial evaluation of UTI. Not only does it have a very high sensitivity and specificity for differentiating parenchymal from collecting system disease, but it also provides an accurate quantitative measurement of function and in combination with radioiodinated orthoiodohippurate renography and Lasix (furosemide; Abbott Laboratories, North Chicago) diuresis will also differentiate significant obstruction from stasis. The use of radionuclide techniques opens new vistas for the investigation of UTI. Cortical scintigraphy should become the gold standard by which other technologies, therapy, and theoretical considerations of pyelonephritis are measured.

Scintigraphic Localization of Adrenal Lesions in Primary Aldosteronism

Dexamethasone suppression adrenal cortical scintiscanning was performed in 87 patients with primary aldosteronism. Fifty patients had adrenal cortical adenomas and 37 had bilateral adrenal hyperplasia. The diagnosis of adrenal cortical adenoma was confirmed by surgery in 49 of 50, and bilateral adrenal hyperplasia was confirmed by adrenal vein aldosterone sampling in 33 and at operation in four. Dexamethasone suppression adrenal scintigraphy correctly identified the lesion(s) in 82 of the 87 patients. There were three false-negative and two false-positive adrenal cortical scintiscanning results. Computed tomography was performed in 33 patients and correctly identified 14 of 23 patients with adrenal cortical adenomas and two of 10 patients with bilateral adrenal hyperplasia and bilateral enlarged adrenals, whereas the remaining eight were considered to have normal findings. These data indicate that, when properly performed, adrenal cortical scintigraphy is an accurate and efficacious modality for the localization of adrenal cortical adenomas and in the differentiation of adrenal cortical adenoma from bilateral adrenal hyperplasia in primary aldosteronism.

Scintigraphic localization of adrenal lesions in primary aldosteronism

Dexamethasone suppression adrenal cortical scintiscanning was performed in 87 patients with primary aldosteronism. Fifty patients had adrenal cortical adenomas and 37 had bilateral adrenal hyperplasia. The diagnosis of adrenal cortical adenoma was confirmed by surgery in 49 of 50, and bilateral adrenal hyperplasia was confirmed by adrenal vein aldosterone sampling in 33 and at operation in four. Dexamethasone suppression adrenal scintigraphy correctly identified the lesion(s) in 82 of the 87 patients. There were three false-negative and two false-positive adrenal cortical scintiscanning results. Computed tomography was performed in 33 patients and correctly identified 14 of 23 patients with adrenal cortical adenomas and two of 10 patients with bilateral adrenal hyperplasia and bilateral enlarged adrenals, whereas the remaining eight were considered to have normal findings. These data indicate that, when properly performed, adrenal cortical scintigraphy is an accurate and efficacious modality for the localization of adrenal cortical adenomas and in the differentiation of adrenal cortical adenoma from bilateral adrenal hyperplasia in primary aldosteronism.

The relationship of I-131 6 beta-iodomethyl-19-norcholesterol (NP-59) adrenal cortical uptake to indices of androgen secretion in women with hyperandrogenism.

Dexamethasone suppression (DS) adrenal cortical scintigraphy has been shown to be useful in the detection of the adrenal pathology in women with hyperandrogenism. However, a relationship between adrenal cortical uptake of I-131 6 beta-iodomethylnorcholesterol (NP-59) and the level of adrenal androgen secretion has not been established. A retrospective analysis of DS adrenal scintiscans has been performed on 39 women with hirsutism and hyperandrogenism. In 14 patients with normal patterns of imaging, in vivo adrenal gland iodocholesterol uptake, calculated using a semi-operator-independent-computer algorithm, did not correlate with the excretion of urinary 17-ketosteroids (17-KS). In contrast, in 20 patients demonstrating abnormal bilateral early imaging patterns, adrenal gland NP-59 uptake correlated significantly with the level of urinary 17-KS excretion (r = 0.65, P less than 0.05). To date seven of these 20 patients have had confirmatory procedures documenting the adrenal glands as contributing sites of androgen secretion. A similar correlation with urinary 17-KS excretion was seen in five other patients with unilateral imaging patterns (r = 0.94, P less than 0.005), due to androgen-secreting adrenal cortical adenomas. No correlation between adrenal NP-59 uptake and plasma testosterone or dehydroepiandrosterone sulphate levels was observed in any of the groups. Thus, adrenal gland uptake of NP-59 under DS reflects a measure of androgen secretion in women with androgen excess.

The role of pharmacologic manipulation in adrenal cortical scintigraphy

Adrenal scintigraphy is a unique nuclear medicine procedure that provides noninvasive, functional information concerning the status of the adrenal cortex. The uptake of iodocholesterol, in addition to localizing adrenal cortical abnormalities, can be manipulate to focus on adrenal cortical dysfunction in either the aldosterone, cortisol, or androgenproducing portions of the adrenal cortex. The uptake of iodocholesterol correlates significantly with the abnormal secretion of cortisol in Cushing's syndrome, aldosterone in the model of adrenal zona glomerulosa function, and adrenal androgen secretion in hyperandorgenism. For these reasons, adrenal scintigraphy is an important diagnostic modality in the evaluation of adrenal cortical function.