Comparison of MRI and renal cortical scintigraphy findings in childhood acute pyelonephritis: preliminary experience

doi:10.1016/S0720-048X(02)00350-9

European Journal of Radiology

Volume 49, Issue 1, January 2004, Pages 76-80

https://doi.org/10.1016/S0720-048X(02)00350-9 Get rights and content

Abstract

Objective: The diagnosis of acute pyelonephritis in children remains a clinical challenge. It may cause permanent renal scar formation and results in the chronic renal failure if prompt diagnosis and treatment are delayed. The purpose of this study is to compare magnetic resonance imaging (MRI) and renal cortical scintigraphy (RCS) findings in childhood acute pyelonephritis and to determine pyelonephritic foci in the acute phase. Materials and method: Twenty children (15 females and five males) with symptoms dysuria, enuresis, costovertebral pain, fever of 37.5 °C or more and/or positive urine culture were imaged by unenhanced turbo spin echo T2, spin echo T1-weighted, pre- and post-gadolinium inversion recovery MRI and RCS. Both imaging techniques were read independently by two radiologists and nuclear medicine specialists. Sensitivity and specificity of MRI in detecting acute pyelonephritic foci and scar lesions were calculated. Furthermore, in order to calculate the reliability of MRI over RCS in differentiating scar tissue and acute pyelonephritic foci, follow-up MRI studies were done in six patients after treatment of acute pyelonephritis. Results: Sensitivity and specificity of MRI in the detection of pyelonephritic lesions were found to be 90.9 and 88.8%, respectively. There is no statistically significant difference in lesion detection between the two diagnostic modalities (P>0.05). Conclusion: Post-gadolinium MR images show significant correlation with RCS in the determination of renal pathology. Moreover, the ability of discriminating acute pyelonephritic foci and renal scar in early stages of disease is the superiority of MRI.

Introduction

Acute pyelonephritis is a critical disease, which may cause permanent renal scar formation and result in chronic renal failure if prompt diagnosis and treatment are delayed.

Currently, technetium (Tc)-99m dimercaptosuccinate (DMSA) is accepted as the gold standard in detecting pyelonephritic scar. The sensitivity of DMSA has been reported to range between 80 and 100% [1], [2], [9], [10]. However, DMSA is unable to differentiate pyelonephritic foci and permanent renal scar. The final diagnosis is usually reached 6 months later by follow-up scintigraphy. In the mean time, the patient is assumed to have acute pyelonephritis and receives intravenous antibiotic treatment.

In an animal study, magnetic resonance imaging (MRI) has been reported to be an alternative diagnostic modality in detecting pyelonephritic foci in the acute phase with a sensitivity of 91% and specificity of 93% [3]. In this study, children with suspected acute pyelonephritis were imaged by MRI after intravenous gadolinium injection and the results were compared with DMSA in a double-blinded fashion.

Section snippets

Materials and methods

Twenty children (15 females and five males) with symptoms of dysuria, enuresis, costovertebral pain, fever of 37.5 °C or more, and/or a positive urine culture were imaged by MRI and renal cortical scintigraphy (RCS). The ages of the patients ranged between 2 and 14 years with a mean age of 7.3±3.4 years. Patients underwent the two imaging studies, MRI and RCS, within a week in either order.

Exclusion criteria from the study included elevated levels of serum creatinine, allergy to gadopentate

Results

Both MRI and RCS demonstrated evidence of lesions in 11 patients (55%). Both showed correspondence as being positive in 10 and negative in 8 (Table 1).

While six (54.5%) out of 11 patients were diagnosed as acute pyelonephritis by MRI, only two patients (18.2%) were read as most likely acute pyelonephritis by RCS. In five patients (45.5%), scar tissue was detected by MRI, only two patients (18.2%) were read as most likely scar tissue by RCS (Table 2). In seven patients (63.6%), suspected acute

Discussion

The correct and early diagnosis of childhood acute pyelonephritis is important for initiation of prompt treatment. Patients with the diagnosis of acute pyelonephritis undergo intravenous antibiotic treatment and are hospitalised [4]. Therefore, early identification of pyelonephritic foci and differentiation from scar tissue are important for the management of treatment and prognosis.

Tc-99m DMSA is accepted as the gold standard in the diagnosis of acute pyelonephritis [5], [6], [7], [8], [9].

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Cited by (38)

ACR Appropriateness Criteria® Acute Pyelonephritis: 2022 Update
2022, Journal of the American College of Radiology
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The excretory phase of MRU does not confer additional benefit with respect to detection and characterization of APN in a complicated patient. Studies comparing MRU with DMSA renal scintigraphy for the detection of pyelonephritis and renal scaring have shown that MRU without and with IV contrast is at least equivalent or superior to DMSA for this specific purpose [33-35]. No studies of MRU without IV contrast were identified in the literature.
Acute pyelonephritis (APN) is a severe urinary tract infection (UTI) that has the potential to cause sepsis, shock, and death. In the majority of patients, uncomplicated APN is diagnosed clinically and is responsive to treatment with appropriate antibiotics. In patients who are high risk or when treatment is delayed, microabscesses may coalesce to form an acute renal abscess. High-risk patients include those with a prior history of pyelonephritis, lack of response to therapy for lower UTI or for APN, diabetes, anatomic or congenital abnormalities of the urinary system, infections by treatment-resistant organisms, nosocomial infection, urolithiasis, renal obstruction, prior renal surgery, advanced age, pregnancy, renal transplant recipients, and immunosuppressed or immunocompromised patients. Pregnant patients and patients with renal transplants on immunosuppression are at an elevated risk of severe complications. Imaging studies are often requested to aid with the diagnosis, identify precipitating factors, and differentiate lower UTI from renal parenchymal involvement, particularly in high-risk individuals. Imaging is usually not appropriate for the first-time presentation of suspected APN in an uncomplicated patient. The primary imaging modalities used in high-risk patients with suspected APN are CT, MRI, and ultrasound, although CT was usually not appropriate for initial imaging in a pregnant patient with no other complications. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.
ACR Appropriateness Criteria<sup>®</sup> Acute Pyelonephritis
2018, Journal of the American College of Radiology
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MRU combines high spatial resolution with assessment of renal function and drainage. Several studies comparing MRU to DMSA renal scintigraphy for the detection of pyelonephritis and renal scarring have shown MRU to be at least equivalent or superior to DMSA renal scintigraphy [27-29]. MRU can distinguish among acute pyelonephritis, renal scarring, and renal dysplasia [30].
Pyelonephritis refers to infection involving the renal parenchyma and renal pelvis. In most patients, uncomplicated pyelonephritis is diagnosed clinically and responds quickly to appropriate antibiotic treatment. If treatment is delayed, the patient is immunocompromised, or for other reasons, microabscesses that form during the acute phase of pyelonephritis may coalesce, forming a renal abscess. Patients with underlying diabetes are more vulnerable to complications, including emphysematous pyelonephritis in addition to abscess formation. Additionally, diabetics may not have the typical flank tenderness that helps to differentiate pyelonephritis from a lower urinary tract infection. Additional high-risk populations may include those with anatomic abnormalities of the urinary tract, vesicoureteral reflux, obstruction, pregnancy, nosocomial infection, or infection by treatment-resistant pathogens. Treatment goals include symptom relief, elimination of infection to avoid renal damage, and identification of predisposing factors to avoid future recurrences. The primary imaging modalities used in patients with pyelonephritis are CT, MRI, and ultrasound.
The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.
Ultrasound of the paediatric urogenital tract
2014, European Journal of Radiology
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Sometimes the urine may be echogenic due to pyuria. DMSA or MRI has a far better sensitivity for the detection of loss of nephrons and renal scarring [8–11]. However, it is still important to measure the kidneys and to provide serial measurements in children with multiple scans.
Pathology in the urinary tract is one of the most frequent queries when children are referred for an ultrasound examination. Comprehensive ultrasound examinations can answer most clinical questions of the urogenital tract with minimal patient preparation and without the use of ionising radiation. Therefore, optimised imaging protocols should be available in all radiology departments where children are examined. This review suggests a preferred imaging protocol for urogenital imaging in children and gives an overview of the different structures of the urogenital tract, the normal age-related sonographic anatomy, and gives examples of the most commonly encountered diseases of the urogenital system in children.
Comparison of magnetic resonance urography to dimercaptosuccinic acid scan for the identification of renal parenchyma defects in children with vesicoureteral reflux
2014, Journal of Pediatric Urology
Citation Excerpt :
Although several studies have compared MRU to DMSA scan in the detection of pyelonephritic lesions in children with febrile UTIs and found no difference in accuracy, the identification of pyelonephritis was not part of our study design [15,28]. Interestingly, in one of these studies, MRU had the additional benefit of being superior in distinguishing pyelonephritis from renal scars [28]. MRU can also identify and characterize small lesions that are not visible on DMSA scan.
The objective of this study was to compare the accuracy of dimercaptosuccinic acid (DMSA) renal scan to magnetic resonance urography (MRU) in the identification of renal parenchyma defects (RPD).
Twenty-five children with history of acute pyelonephritis and vesicoureteral reflux underwent DMSA scan and MRU to determine the presence of RPD. DMSA scans and MRUs were each evaluated by two radiologists and agreement achieved by consensus. Discordant DMSA–MRU findings were re-evaluated in a side-by-side comparison and an ultimate consensus reached.
The ultimate consensus diagnosis was 18 kidneys with RPDs in 15 patients, of which five were classified as mild RPDs, six as moderate RPDs, and seven as severe RPDs. Although DMSA scan and MRU were similar in their ability to diagnose RPDs, MRU was considered to represent the true diagnosis in 11 of the 12 discordant cases in consensus review by four pediatric radiologists. MRU showed a much higher inter-observer agreement with a weighted kappa of 0.96 for both kidneys compared to 0.71 for the right kidney and 0.86 for the left kidney by DMSA scan.
Our results suggest that MRU is superior to DMSA scan in the identification of renal parenchyma defects.
Imaging the Pediatric Urinary Tract
2008, Comprehensive Pediatric Nephrology: Text with CD-ROM
Imaging the Pediatric Urinary Tract
2008, Comprehensive Pediatric Nephrology

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Comparison of MRI and renal cortical scintigraphy findings in childhood acute pyelonephritis: preliminary experience

Abstract

Introduction

Section snippets

Materials and methods

Results

Discussion

Semin. Nucl. Med.

J. Urol.

Childhood pyelonephritis: comparison of gadolinium-enhanced MR imaging and renal cortical scintigraphy for diagnosis

Radiology

Experimental pyelonephritis in piglets: diagnosis with MR imaging

Radiology

Diagnosis of acute pyelonephritis in children: comparison of sonography and Tc-99m DMSA scintigraphy

Am. J. Roentgenol.

Tc-99m DMSA scan in the diagnosis of acute pyelonephritis in children: relation to clinical and radiological findings

Pediatr. Nephrol.