Pictorial review: computed tomography of renal inflammatory disease

Clinical Usefulness of Contrast-Enhanced Computed Tomography in Patients with Non-Obstructive Acute Pyleonephritis

Objectives The aim of this study is to investigate the clinical utility of contrast-enhanced computed tomography (CE-CT) in patient with non-obstrcutive acute pyelonephritis (APN). Methods From 2007 to 2013, 537 APN patients who underwent a CE-CT scan within 24 hours after hospital admission were enrolled. We divided these patients into greater (50% or greater involvment, n = 143) and lesser (less than 50% involvement, n = 394) groups based on renal parenchymal involvement in CE-CT examination. We compared clinical characteristics between two groups and analyzed the clinical value of CE-CT scan as a reliable marker for predicting clinical severity and disease course in patient with non-obstructive APN. Results The mean estimated glomerular filtration rate was 70.6 ± 25.5 mL/min/1.73m2. Compared with patients in lesser group, the patients in greater group had lower serum albumin levels (3.5 ± 0.5 vs 3.8 ± 0.6, P < 0.01) and longer hosptal stay (10.1 ± 4.7 vs 8.8 ± 4.5, P < 0.05). In addition, acute kidney injury (AKI) (23.1% vs 11.4%, P < 0.005) and bacteremia (36.4% vs 26.8%, P = 0.02) were frequently developed in greater group, respectively. The overall incidence of AKI was 14.8% based on RIFLE criteria. In a multivariate logistic regression analysis for predciting AKI, age, presence of diabetes mellitus and the presence of renal parenchymal involvement of greater than 50% in CE-CT were significant predictors of AKI. Conclusions The CE-CT scan could be useful to predict the clinical severity and course in non-obstructive APN patients with preserved renal function.

Clinical Usefulness of Unenhanced Computed Tomography in Patients with Acute Pyelonephritis

BACKGROUND

Unenhanced computed tomography (UCT) may be useful for evaluating acute pyelonephritis; however, no study has compared UCT with enhanced computed tomography (ECT) as a diagnostic tool. We evaluated a clinical usefulness of UCT versus ECT in acute pyelonephritis (APN).

METHODS

We reviewed the clinical and radiological data from 183 APN-suspected patients who underwent UCT and ECT simultaneously at emergency room (ER) over a two-year period. Demographic, clinical parameters and computed tomography (CT) parameters of 149 patients were compared.

RESULTS

The average patient age was 61.2 (± 10) years: 31 patients were men. Ninety-nine (66.4%) patients showed stones (18.7%), perinephric infiltration (56%), swelling (21%), and hydronephrosis (6.7%) on UCT. Seventeen patients (11.4%) had an atypical clinical course, requiring additional tests for accurate diagnosis. In 7 patients UCT and ECT results did not differ; in 10 patients, the diagnosis changed on ECT. On ECT, 112/149 (75.2%) patients had stones (16.7%), perinephric infiltrations (57%), swelling (21%), and hydronephrosis (6.7%); 62.5% showed parenchymal involvement: 34 (22.8%) patients had no abnormal ECT findings. APN CT findings are similar on stone, perinephric infiltration, swelling and hydronephrosis on both CTs. Twelve patients (8.0%) had an abnormal ECT finding, i.e., low-grade (1 and 2) parenchymal involvement. Six (4%) patients developed contrast-induced acute kidney injury within 2 days after ECT.

CONCLUSION

We demonstrate that UCT is not inferior to ECT as an initial tool for evaluating APN for screening nephrolithiasis and hydronephrosis without the risk of contrast-induced acute kidney injury (CIAKI). However, patients with an atypical clinical course may still need ECT.

Relationship between uncommon computed tomography findings and clinical aspects in patients with acute pyelonephritis

Purpose

Computed tomography (CT) has become popular in the diagnosis of acute pyelonephritis (APN) and its related complications in adults. The aim of this study was to investigate the relationship between uncommon CT findings and clinical and laboratory data in patients with APN.

Materials and Methods

From July 2009 to July 2012, CT findings and clinical data were collected from 125 female patients with APN. The six uncommon CT findings (excluding a wedge-shaped area of hypoperfusion in the renal parenchyma) studied were perirenal fat infiltration, ureteral wall edema, renal abscess formation, pelvic ascites, periportal edema, and renal scarring. The clinical parameters analyzed were the age and body mass index of the patients as well as the degree and duration of fever. Laboratory parameters related to inflammation and infection included white blood cell count, C-reactive protein (CRP) level, erythrocyte sedimentation rate, pyuria, and bacteriuria.

Results

The most common CT finding was perirenal fat infiltration (69 cases, 55%). A longer duration of fever, higher CRP level, and grade of pyuria were related with perirenal fat infiltration (p=0.010, p=0.003, and p=0.049, respectively). The CRP level was significantly higher in patients with renal abscess and ureteral wall edema (p=0.005 and p=0.015, respectively).

Conclusions

The uncommon CT findings that were related to aggravated clinical and laboratory parameters of APN patients were perirenal fat infiltration, ureteral wall edema, and renal abscess formation. The inflammatory reaction and tissue destruction may be more aggressive in patients with these CT findings.

Tuberculosis of the genitourinary system-Urinary tract tuberculosis: Renal tuberculosis-Part II

This article reviews the computed tomography and magnetic resonance imaging (MRI) features of renal tuberculosis (TB), including TB in transplant recipients and immunocompromised patients. Multi detector computed tomography (MDCT) forms the mainstay of cross-sectional imaging in renal TB. It can easily identify calcification, renal scars, mass lesions, and urothelial thickening. The combination of uneven caliectasis, with urothelial thickening and lack of pelvic dilatation, can also be demonstrated on MDCT. MRI is a sensitive modality for demonstration of features of renal TB, including tissue edema, asymmetric perinephric fat stranding, and thickening of Gerota's fascia, all of which may be clues to focal pyelonephritis of tuberculous origin. Diffusion-weighted MR imaging with apparent diffusion coefficient (ADC) values may help in differentiating hydronephrosis from pyonephrosis. ADC values also have the potential to serve as a sensitive non-invasive biomarker of renal fibrosis. Immunocompromised patients are at increased risk of renal TB. In transplant patients, renal TB, including tuberculous interstitial nephritis, is an important cause of graft dysfunction. Renal TB in patients with HIV more often shows greater parenchymal affection, with poorly formed granulomas and relatively less frequent findings of caseation and stenosis. Atypical mycobacterial infections are also more common in immunocompromised patients.

Infectious and inflammatory diseases of the kidney

Although the most common renal infection, acute pyelonephritis, can typically be diagnosed on clinical and laboratory examinations, radiologic studies play a role in evaluating for complications and in examining the high-risk patient for more serious complications and atypical infections. It is imperative that the radiologist be familiar with renal infections beyond the common acute pyelonephritis.

Freqüência dos sinais de pielonefrite aguda em pacientes submetidos a tomografia computadorizada

OBJETIVO: Estimar a freqüência das alterações tomográficas renais e extra-renais em pacientes com pielonefrite aguda e avaliar o grau de concordância interobservador. MATERIAIS E MÉTODOS: Realizamos trabalho retrospectivo a partir da análise dos exames de tomografia computadorizada de 47 pacientes com diagnóstico clínico e laboratorial de pielonefrite aguda. Dois examinadores independentes avaliaram as principais alterações renais, perirrenais e extra-renais. Foi medida a freqüência dos achados tomográficos e a concordância interobservador por meio do teste kappa (kapa). RESULTADOS: A freqüência dos achados tomográficos para os diversos parâmetros estudados foi: nefrograma heterogêneo, 100%; nefromegalia, 65%; heterogeneidade da gordura, 62,5%; nefrolitíase, 16,6%; abscessos, 21%; derrame pleural, 36%; espessamento da vesícula biliar, 32,5%; edema periportal, 32,5%. O teste kapa para a concordância interobservador demonstrou reprodutibilidade variando entre moderada (kapa = 0,511 para nefromegalia) e quase perfeita (kapa = 0,87 para nefrograma heterogêneo) para todos os parâmetros estudados, exceto para a heterogeneidade da gordura perirrenal (kapa = 0,268). CONCLUSÃO: A freqüência dos diversos achados tomográficos de pielonefrite aguda é elevada, sendo o nefrograma heterogêneo o sinal mais comum. Alterações perinefréticas e extra-renais são observadas em até dois terços dos casos. A tomografia computadorizada apresenta boa concordância interobservador.

Extrarenal manifestations of severe acute pyelonephritis: CT findings in 21 cases

The aim of this study is to report the extrarenal computerized tomography (CT) findings in patients with acute pyelonephritis (APN). Twenty-one CT examinations of 20 patients [19 women and one man, with ages ranging from 18 to 57 years (mean -35.2 years)], presenting either with a clinical diagnosis of APN (n=17) or with a suspected acute appendicitis, fever of unknown origin, and adult respiratory distress syndrome, one in each, were retrospectively reviewed. None had a known preexisting systemic disease. Results showed that renal abnormalities were seen on CT in all patients. In addition, ascites was detected in all women patients associated with subcutaneous edema in five of them. A thickened gallbladder wall was found in 19 cases, all were women, and periportal tracking and a dilated inferior vena cava in 17 CTs. Pleural effusion and thickened interlobular septa were present in 16 and 15 studies, respectively. Relevant laboratory findings included hypoalbuminemia in 14, elevated liver enzymes in 11, hypocholesterolemia in nine, and elevated LDH levels in six cases. In conclusion, radiologists should be familiar with the extrarenal imaging features of APN that may be seen on CT, and on ultrasonography as well, and should look for renal abnormalities to diagnose a clinically unsuspected APN. Alternatively, APN should be included in the differential diagnosis of systemic diseases that cause gallbladder wall thickening to avoid misdiagnosing it as acute cholecystitis.

Imaging features

Diagnosis of urogenital tuberculosis is traditionally based on urography, but the last few decades have seen the contribution of new methods such as ultrasound, CT scan and NMR. In the authors’ experience urography is still first choice for diagnosing urogenital tuberculosis; ultrasound is a useful complement in assessing renal parenchymal lesions and is indispensable in defining lesions in the prostate and the epididymus. With regard to the CT scan, the authors consider it gives a better definition of anatomical ratios than ultrasound, being particularly useful with extensive lesions. The role of NMR is not yet well-defined, although it does not seem to offer any particular advantages compared to CT.

Xanthogranulomatous pyelonephritis in a renal allograft recipient

Xanthogranulomatous pyelonephritis rarely occurs in renal allografts. This is the fifth reported case. Diagnosis was made by renal biopsy, which is usually performed to evaluate an elevated serum creatinine. Associated patient symptomology is nonspecific, and graft imaging with ultrasonography and computed tomography was not helpful as it would be with native kidney xanthogranulomatous pyelonephritis. Successful treatment with antibiotics may depend on the serum creatinine at presentation. Prognosis, therefore, is guarded, with a common outcome of irreversible renal dysfunction.

Renal and perirenal abscesses

Our knowledge of the spectrum of renal abscesses has evolved as a result of more sensitive radiologic techniques. The classification of intrarenal abscesses currently includes acute focal bacterial nephritis, acute multifocal bacterial nephritis, renal cortical abscess, renal corticomedullary abscess, and xanthogranulomatous pyelonephritis. The clinical presentation of these entities does not differentiate them, however, and various radiographic studies are helpful in making the diagnosis. The intrarenal abscess is usually treated successfully with antibiotic therapy alone. Antistaphylococcal therapy is indicated for the renal cortical abscess, whereas therapy directed against the common gram-negative uropathogens is indicated for most of the other entities. The perinephric abscess is often an elusive diagnosis, has a more serious prognosis, and is more difficult to treat. Drainage of the abscess and sometimes partial or complete nephrectomy, in addition to antibiotic therapy, are required for resolution.

Recurrent Staphylococcus aureus renal abscess in a child positive for the human immunodeficiency virus

A 10-year-old girl with the human immunodeficiency virus was found to have a Staphylococcus aureus renal abscess with perinephric extension. The abscess was drained first percutaneously and then surgically, and the patient received a 6-week course of intravenous antibiotics. Three months later, the abscess recurred, necessitating a nephrectomy. The extended morbidity and difficulty of eradicating S aureus suggest that, in immunocompromised patients, early aggressive surgical management is indicated.