Imaging in urinary tract infections: current strategies and new trends

Is there a relationship between renal scarring and neutrophil-to-lymphocyte ratio in patients with vesicoureteral reflux?

OBJECTIVES

Vesicoureteral reflux (VUR) exacerbates the risk of renal scarring by establishing a ground for pyelonephritis. It is known that the inflammatory process is more influential than the direct damage caused by bacterial infection in the development of renal scars after pyelonephritis. Therefore, the present study aims to investigate the relationship between renal scarring and systemic inflammatory markers in patients with VUR.

MATERIAL AND METHODS

Hundred and ninety-two patients (116 females, 76 males) diagnosed with VUR were divided into two groups based on the presence or absence of renal scarring and into three groups according to the grade of VUR (low, moderate and high). Neutrophil count, lymphocyte count, mean platelet volume (MPV) and neutrophil-to-lymphocyte ratio (NLR) were compared among the groups.

RESULTS

Of the 192 patients, 102 had renal scarring. The age and gender distribution did not differ significantly between the groups with and without renal scarring (p > 0.05). However, the grade of reflux and lymphocyte count were significantly higher in the group with renal scarring (p < 0.05), and the NLR was significantly lower in the group with renal scarring (p < 0.05). The lymphocyte count was significantly higher (p < 0.05) and NLR was significantly lower in the high-grade VUR group (p < 0.05). However, MPV values did not differ significantly (p > 0.05) between the groups.

CONCLUSIONS

NLR can be used to predict renal scarring in patients with VUR, especially in the period of 3-6 months after the first attack of infection, and may even serve as a candidate marker for treatment selection. However, larger series and prospective studies are needed.

Effect of Ursodeoxycholic Acid on the Biodistribution and Excretion of Technetium-99m Radiopharmaceuticals in Rat: A Potential Image Quality Enhancer

PURPOSE

This study aimed to investigate the effect of ursodeoxycholic acid (UDCA) on the biodistribution and excretion of technetium-99m (Tc-99m)-labeled radiopharmaceuticals.

MATERIALS AND METHODS

Tc-99m hydroxy-methylene-diphosphonate (HDP), Tc-99m pertechnetate, and Tc-99m dimercaptosuccinic acid (DMSA) were injected via the tail vein of rats. After 30 min, the control group was administered saline, and the UDCA group was given UDCA orally. Scintigraphy images were acquired after 30 min and 1, 2, 3, and 4 h. Radioactivity and rate of change were compared. Tc-99m mercaptoacetyltriglycine (MAG₃) imaging was also performed.

RESULTS

In image analysis of Tc-99m HDP, radioactivity of the buttock was lower in the UDCA group at 4 h. Rates of change in the buttock were significantly different at 3 h-30 min and 4 h-30 min, and buttock radioactivity in the UDCA group had decreased more. In analysis of Tc-99m pertechnetate, radioactivity of the buttock was higher in the control group. Rates of change in the thyroid gland and buttock were different at 1 h-30 min, 3 h-30 min, and 4 h-30 min, with radioactivity in the UDCA group decreasing more. In the analysis of Tc-99m DMSA, while the radioactivity of the kidneys in the control group showed little decrease at 1 h-30 min, that in the UDCA group increased. In the analysis of Tc-99m MAG₃ images, radioactivity and radioactivity/total body radioactivity (TBA) values for the kidneys were higher in the UDCA group at 2 min. At 5 and 10 min, radioactivity/TBA values for soft tissue in the UDCA group were lower than those in the control group.

CONCLUSION

This study demonstrated that administration of UDCA increases renal excretion and soft tissue clearance of radiopharmaceuticals. This investigation could contribute to the broadening of applications of UDCA.

Evaluation of cyclic direct radionuclide cystography findings with DMSA scintigraphy results in children with a prior diagnosis of vesicoureteral reflux

OBJECTIVES

Direct radionuclide cystography (DRC) with cyclic imaging is a sensitive method used for the detection of vesicoureteral reflux (VUR). Radionuclide cystography is generally recommended for follow-up evaluation of VUR. The aim of this study was to evaluate cyclic DRC with DMSA scan results during the follow-up period in children with a prior diagnosis of VUR.

PATIENTS AND METHODS

DRC findings of 85 children with VUR were evaluated together with DMSA findings during follow-up. VUR grade was classified anatomically as grades I, II, and III reflux. Reflux grades of II and III were regarded as high-grade reflux. Reflux was also graded functionally as transient and continuous on the basis of the presence of reflux on either filling or voiding phases (transient) or both phases (continuous) of at least one cycle.

RESULTS

Among 85 children, 32 (38%) exhibited reflux. In five patients, reflux was observed on both sides, and a total of 37 refluxing units (RUs) were evaluated. According to the highest grade attained in either cycle, 31 (84%) units had grade II, five had grade I and one had grade III reflux. Reflux was continuous in 23 (62%) and transient in 14 (38%) RUs. The incidence of an abnormal scan result was higher in continuous reflux group (78%) than in high-grade anatomic reflux group (59%). The addition of a second cycle resulted in the diagnosis of continuous reflux in six (26%) more RUs. DMSA scan findings correlated significantly with functional reflux classification (P<0.05), but not with anatomic reflux classification (P>0.05).

CONCLUSION

Functional classification of VUR into continuous and transient reflux resulted in higher correlation with DMSA scan findings compared with anatomic reflux grading in follow-up patients with VUR. Cyclic imaging contributed to continuous reflux diagnosis. The significance of functional information obtained from cyclic DRC in initial diagnostic workup, management, and follow-up of children with urinary tract infection needs to be determined with further studies.

Urinary Tract Infection in Children

BACKGROUND

Urinary Tract Infection (UTI) is a common infection in children. Prompt diagnosis and appropriate treatment are very important to reduce the morbidity associated with this condition.

OBJECTIVE

To provide an update on the evaluation, diagnosis, and treatment of urinary tract infection in children.

METHODS

A PubMed search was completed in clinical queries using the key terms "urinary tract infection", "pyelonephritis" OR "cystitis". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature and the pediatric age group. Patents were searched using the key terms "urinary tract infection" "pyelonephritis" OR "cystitis" from www.google.com/patents, http://espacenet.com, and www.freepatentsonline.com.

RESULTS

Escherichia coli accounts for 80 to 90% of UTI in children. The symptoms and signs are nonspecific throughout infancy. Unexplained fever is the most common symptom of UTI during the first two years of life. After the second year of life, symptoms and signs of pyelonephritis include fever, chills, rigor, flank pain, and costovertebral angle tenderness. Lower tract symptoms and signs include suprapubic pain, dysuria, urinary frequency, urgency, cloudy urine, malodorous urine, and suprapubic tenderness. A urinalysis and urine culture should be performed when UTI is suspected. In the work-up of children with UTI, physicians must judiciously utilize imaging studies to minimize exposure of children to radiation. While waiting for the culture results, prompt antibiotic therapy is indicated for symptomatic UTI based on clinical findings and positive urinalysis to eradicate the infection and improve clinical outcome. The choice of antibiotics should take into consideration local data on antibiotic resistance patterns. Recent patents related to the management of UTI are discussed.

CONCLUSION

Currently, a second or third generation cephalosporin and amoxicillin-clavulanate are drugs of choice in the treatment of acute uncomplicated UTI. Parenteral antibiotic therapy is recommended for infants ≤ 2 months and any child who is toxic-looking, hemodynamically unstable, immunocompromised, unable to tolerate oral medication, or not responding to oral medication. A combination of intravenous ampicillin and intravenous/intramuscular gentamycin or a third-generation cephalosporin can be used in those situations. Routine antimicrobial prophylaxis is rarely justified, but continuous antimicrobial prophylaxis should be considered for children with frequent febrile UTI.

Practical approach to screen vesicoureteral reflux after a first urinary tract infection

Introduction:

Vesicoureteral reflux (VUR) is a common pediatric urologic disorder. After the first urinary tract infection (UTI), imaging studies are recommended, starting with a renal ultrasound (RUS). Voiding cystourethrography (VCUG) and dimercaptosuccinic acid (DMSA) scan are the other main radiologic studies used to detect VUR. We evaluated the use of RUS as a screening method for VUR in children below 2 years of age, in order to avoid unnecessary VCUG.

Materials and Methods:

Medical records and imaging studies of infants (<2 years) who had their first UTI in a 6 year period were retrospectively reviewed. We evaluated the sensitivity, specificity, and negative predictive values of RUS and DMSA for diagnosing VUR.

Results:

Among 155 children (51% males) with their first UTI, 148 RUS were performed, 128 VCUG and 29 DMSA. VUR was detected in 21% patients; 14.5% low grade and 6.5% high grade. One hundred and twenty-one patients underwent both RUS and VCUG, 101 RUS were normal and 20 abnormal. Of the normal RUS 98% had no or low grade VUR. Among those with an abnormality on RUS 30% had high grade VUR (P < 0.001).

Conclusions:

After the first UTI in infants (<2 years) RUS is a good screening method for VUR. Among such shildren with a normal RUS, we do not recommend VCUG or DMSA. In our opinion, VCUG should be performed only in patients with abnormal findings in RUS or in recurrent UTI.

Radionuclides in nephrourology, Part 2: pitfalls and diagnostic applications

Radionuclide renal scintigraphy provides important functional data to assist in the diagnosis and management of patients with a variety of suspected genitourinary tract problems, but the procedures are underutilized. Maximizing the utility of the available studies (as well as the perception of utility by referring physicians) requires a clear understanding of the clinical question, attention to quality control, acquisition of the essential elements necessary to produce an informed interpretation, and production of a report that presents a coherent impression based on data contained in the report and that specifically addresses the clinical question. To help achieve these goals, part 1 of this review addressed the available radiopharmaceuticals, quality control, and quantitative indices, including the measurement of absolute and relative renal function. Part 2 assumes familiarity with part 1 and focuses on the common clinical indications of suspected obstruction and renovascular hypertension; part 2 also summarizes the status of radionuclide renal imaging in the evaluation of the transplanted kidney and the detection of infection, discusses potential pitfalls, and concludes with suggestions for future research. The series of SAM questions accompanying parts 1 and 2 has been designed to reinforce and extend points made in the review. Although the primary focus is the adult patient, aspects of the review also apply to the pediatric population.

Adequacy of paediatric renal tract ultrasound requests and reports in a general radiology department

BACKGROUND

According to current guidelines, US is the most important modality for imaging urinary tract infections (UTI) in children.

OBJECTIVES

(1) To assess the adequacy of paediatric renal US requests and reports in a general radiology department, and correlate the request adequacy and the performing radiologist's experience with report adequacy. (2) To determine the yield of abnormal findings.

MATERIALS AND METHODS

Retrospective review of renal US requests. The information was scored: requests 0-3 (3 as highest adequacy) and reports 0-21 (21 as highest adequacy). Correlation tests used included Spearman's correlation, Kruskal-Wallis test, Chi-square test of independence and Fisher exact test.

RESULTS

Mean report adequacy score was 6.67/21. Trainees did 87% of all scans and performed better (score 6.76) than the staff radiologists (score 6.08). Hydronephrosis was the most common abnormality. There was no correlation between request or reporter rank and reporting adequacy.

CONCLUSION

Renal US requests and reports are inadequate. To improve reporting standards for trainees and specialists, a renal ultrasound reporting template was designed for use.

Hepatic and pulmonary nodular lesions in pediatric urinary tract infections

One of the major goals in investigating children with urinary tract infection (UTI) is to recognize patients at risk of further UTI-related problems. This study reports the clinical features of 19 pediatric patients with UTIs in whom associated hepatic and/or pulmonary nodules were incidentally diagnosed by the imaging tests performed for the UTI. Hepatic nodules in five patients were detected on ultrasound scans, and pulmonary nodules and both hepatic and pulmonary nodules were detected in 12 and two children by dimercaptosuccinic acid scintigraphy. The mean age of the patients was 24.5 months. Vesicoureteral reflux (VUR) was detected in nine of 17 patients (52.9%), acute pyelonephritis was identified in nine of 18 patients, and renal scarring was found in 57.1% patients with pyelonephritis. On follow-up, the hepatic and/or pulmonary nodules regressed in all patients. About 85.7% of patients experienced a recurrence of UTI within 1 year. In comparison with age- and sex-matched controls with UTIs without pulmonary or hepatic nodules, the presence of VUR and the recurrence of UTI within 1 year were higher in patients with UTIs and nodules (P<0.05). The hepatic and/or pulmonary nodules identified on the ultrasound scan and by dimercaptosuccinic acid scintigraphy may provide a valuable diagnostic marker for the proper management of patients with an UTI.