Chronic kidney disease is a major medical problem, causing more than a million deaths each year worldwide. Peripheral kidney microvascular damage characterizes most chronic kidney diseases, yet ...noninvasive and quantitative diagnostic tools to measure this are lacking. Ultrasound Localization Microscopy (ULM) can assess tissue microvasculature with unprecedented resolution. Here, we optimized methods on 35 kidney transplants and studied the feasibility of ULM in seven human kidney allografts with a standard low frame rate ultrasound scanner to access microvascular damage. Interlobar, arcuate, cortical radial vessels, and part of the medullary organization were visible on ULM density maps. The medullary vasa recta can be seen but are not as clear as the cortical vessels. Acquisition parameters were derived from Contrast-Enhanced Ultrasound examinations by increasing the duration of the recorded clip at the same plane. ULM images were compared with Color Doppler, Advanced Dynamic Flow, and Superb Microvascular Imaging with a contrast agent. Despite some additional limitations due to movement and saturation artifacts, ULM identified vessels two to four times thinner compared with Doppler modes. The mean ULM smallest analyzable vessel cross section was 0.3 ± 0.2 mm in the seven patients. Additionally, ULM was able to provide quantitative information on blood velocities in the cortical area. Thus, this proof-of-concept study has shown ULM to be a promising imaging technique for qualitative and quantitative microvascular assessment. Imaging native kidneys in patients with kidney diseases will be needed to identify their ULM biomarkers.
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In recent years, several novel ultrasound (US)–based techniques have emerged for kidney diagnostic imaging, including tissue stiffness assessment with elastography, Ultrasensitive Doppler techniques, ...and contrast-enhanced ultrasonography to assess renal microvascularization. Renal elastography has become available with the development of noninvasive quantitative techniques, following the rapidly growing field of liver fibrosis diagnosis. With the increased incidence of chronic kidney disease, noninvasive diagnosis of renal fibrosis can be of critical value. However, it is difficult to simply extend the application of US elastography from one organ to the other due to anatomic and technical issues. Today, renal elastography appears to be a promising application that, however, still requires optimization and validation. New ultrasensitive Doppler techniques improve the detection of slow blood flow and can be used alone or after administration of US contrast agents. These microbubble-based agents are extremely well tolerated and can be administered even in cases of impaired renal function. Despite the lack of approval, they improve the characterization of atypical renal masses, complex cystic renal masses, and peripheral vascular disorders. Dynamic contrast-enhanced US is based on quantification of the signal intensity from region of interest and mathematical fits of the time-intensity curves. Perfusion-related parameters can be extracted for the monitoring of vascular changes in the renal parenchyma and in tumors in order to evaluate drug response. This estimation of renal perfusion depends on many parameters that should be kept constant for follow-up studies, and, when possible, an internal reference should be used to normalize the measurements.
Objectives
To develop technical guidelines for magnetic resonance imaging aimed at characterising renal masses (multiparametric magnetic resonance imaging, mpMRI) and at imaging the bladder and upper ...urinary tract (magnetic resonance urography, MRU).
Methods
The French Society of Genitourinary Imaging organised a Delphi consensus conference with a two-round Delphi survey followed by a face-to-face meeting. Two separate questionnaires were issued for renal mpMRI and for MRU. Consensus was strictly defined using a priori criteria.
Results
Forty-two expert uroradiologists completed both survey rounds with no attrition between the rounds. Fifty-six of 84 (67%) statements of the mpMRI questionnaire and 44/71 (62%) statements of the MRU questionnaire reached final consensus. For mpMRI, there was consensus that no injection of furosemide was needed and that the imaging protocol should include T2-weighted imaging, dual chemical shift imaging, diffusion-weighted imaging (use of multiple
b
-values; maximal
b
-value, 1000 s/mm
2
) and fat-saturated single-bolus multiphase (unenhanced, corticomedullary, nephrographic) contrast-enhanced imaging; late imaging (more than 10 min after injection) was judged optional. For MRU, the patients should void their bladder before the examination. The protocol must include T2-weighted imaging, anatomical fast T1/T2-weighted imaging, diffusion-weighted imaging (use of multiple
b
-values; maximal
b
-value, 1000 s/mm
2
) and fat-saturated single-bolus multiphase (unenhanced, corticomedullary, nephrographic, excretory) contrast-enhanced imaging. An intravenous injection of furosemide is mandatory before the injection of contrast medium. Heavily T2-weighted cholangiopancreatography-like imaging was judged optional.
Conclusion
This expert-based consensus conference provides recommendations to standardise magnetic resonance imaging of kidneys, ureter and bladder.
Key Points
• Multiparametric magnetic resonance imaging (mpMRI) aims at characterising renal masses; magnetic resonance urography (MRU) aims at imaging the urinary bladder and the collecting systems.
• For mpMRI, no injection of furosemide is needed.
• For MRU, an intravenous injection of furosemide is mandatory before the injection of contrast medium; heavily T2-weighted cholangiopancreatography-like imaging is optional.
Abstract
Background
Neurolisteriosis ranks among the most severe neurological infections. Its radiological features have not been thoroughly studied. We describe here the neuroradiological features ...of neurolisteriosis and assess their prognostic value.
Methods
Patients with microbiologically proven neurolisteriosis were enrolled from November 2009 to October 2013 in MONALISA study. Magnetic resonance and computed tomography images were studied by 2 independent neuroradiologists. Predictors of 3-month mortality were determined using logistic regression.
Results
Seventy-one patients were included; 42 were men (59%). Mean age was 64 years. Sixty patients (85%) reported signs of encephalitis, with clinical brainstem involvement in 16 (23%). Images were abnormal in 87% of cases (62/71). Main neuroradiological images were meningeal enhancement (25/71, 35%), abscess(es), or nodular image(s) evocative of abscess (10/71, 14%), hemorrhages (11/71, 15%), contrast-enhancing ventricles, or hydrocephalus (7/71, 10%). White-matter images (42/71, 59%), dilated Virchow-Robin spaces (22/71, 31%), and cerebral atrophy were also reported (34/71, 48%). Brainstem involvement (meningeal enhancement, abscess) was reported in only 7/71 cases (10%). Three-month survival was lower in patients with hydrocephalus or contrast-enhancing ventricles (1/7 14% than without 47/64, 73%, P = .005) and in patients with parenchymal images (abscesses, nodules\, or white matter images; 25/46 54% vs 23/25 without 92%, P = .004). Parenchymal images were associated with lower 3-month survival in the multivariable model (odds ratio 5.60, 95% confidence interval 1.42-29.6, P = .02).
Conclusions
Neurolisteriosis presents as a combination of neuroradiological images, none being specific. Radiological signs of rhombencephalitis are uncommon, whereas, unexpectedly, hemorrhagic images are frequent. The negative prognostic value of parenchymal neuroradiological images was evidenced.
Clinical Trials Registration
NCT01520597
Neurolisteriosis typically presents as a combination of neuroradiological images, including frequent hemorrhagic lesions. Signs of rhombencephalitis are uncommon. Neuroradiological parenchymal abnormal images exhibit a negative prognostic value in patients with neurolisteriosis.
Objectives
To develop technical guidelines for computed tomography urography.
Methods
The French Society of Genitourinary Imaging organised a Delphi consensus conference with a two-round Delphi ...survey followed by a face-to-face meeting. Consensus was strictly defined using a priori criteria.
Results
Forty-two expert uro-radiologists completed both survey rounds with no attrition between the rounds. Ninety-six (70%) of the initial 138 statements of the questionnaire achieved final consensus. An intravenous injection of 20 mg of furosemide before iodinated contrast medium injection was judged mandatory. Improving the quality of excretory phase imaging through oral or intravenous hydration of the patient or through the use of an abdominal compression device was not deemed necessary. The patient should be imaged in the supine position and placed in the prone position only at the radiologist’s request. The choice between single-bolus and split-bolus protocols depends on the context, but split-bolus protocols should be favoured whenever possible to decrease patient irradiation. Repeated single-slice test acquisitions should not be performed to decide of the timing of excretory phase imaging; instead, excretory phase imaging should be performed 7 min after the injection of the contrast medium. The optimal combination of unenhanced, corticomedullary phase and nephrographic phase imaging depends on the context; suggestions of protocols are provided for eight different clinical situations.
Conclusion
This expert-based consensus conference provides recommendations to standardise the imaging protocol for computed tomography urography.
Key Points
•
To improve excretory phase imaging, an intravenous injection of furosemide should be performed before the injection of iodinated contrast medium.
•
Systematic oral or intravenous hydration is not necessary to improve excretory phase imaging.
•
The choice between single-bolus and split-bolus protocols depends on the context, but split-bolus protocols should be favoured whenever possible to decrease patient irradiation.
We report the case of a calcified angiomyolipoma of the kidney, fortuitously discovered on a computed tomography scan of the abdomen. Because of the presence of intratumoral calcification and ...macroscopic fat, renal cell carcinoma could not be ruled out by imaging. Biopsy of the mass was performed, and pathological study confirmed the diagnosis of angiomyolipoma. Biopsy of renal masses containing macroscopic fat and calcification may be considered before nephrectomy.
To prospectively evaluate the performance of real-time ultrasonographic (US) shear-wave elastography (SWE) in the diagnosis of peripheral zone prostate cancer in patients with high and/or increasing ...prostate-specific antigen levels and/or abnormal digital rectal examination results.
After signing an informed consent form, men referred for transrectal prostate biopsy were enrolled in this prospective HIPAA-compliant two-center study, which was conducted with institutional review board approval. Transrectal US SWE of the prostate was performed after a conventional transrectal US examination and immediately before US-guided 12-core sextant biopsy. For each sextant, the maximum SWE value was measured and matched to the pathologic results of that sextant biopsy. The diagnostic performance of SWE was assessed at both patient and sextant levels. The elasticity value maximizing the Youden index was used to derive sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).
The elasticity values were matched to pathologic results for a total of 1040 peripheral zone sextants in 184 men. One hundred twenty-nine positive biopsy findings (size, ≥3 mm; Gleason score, ≥6) were identified in 68 patients. The sextant-level sensitivity, specificity, PPV, NPV, and area under the receiver operating characteristic curve for SWE with a cutoff of 35 kPa for differentiating benign from malignant lesions were 96% (95% confidence interval CI: 95%, 97%), 85% (95% CI: 83%, 87%), 48% (95% CI: 46%, 50%), 99% (95% CI: 98%, 100%), and 95% (95% CI: 93%, 97%), respectively.
Use of a 35-kPa threshold at SWE may provide additional information for the detection and biopsy guidance of prostate cancer, enabling a substantial reduction in the number of biopsies while ensuring that few peripheral zone adenocarcinomas are missed.
Objective
To distinguish benign from malignant cystic renal lesions (CRL) using a contrast-enhanced CT-based radiomics model and a clinical decision algorithm.
Methods
This dual-center retrospective ...study included patients over 18 years old with CRL between 2005 and 2018. The reference standard was histopathology or 4-year imaging follow-up. Training and testing datasets were acquired from two institutions. Quantitative 3D radiomics analyses were performed on nephrographic phase CT images. Ten-fold cross-validated LASSO regression was applied to the training dataset to identify the most discriminative features. A logistic regression model was trained to classify malignancy and tested on the independent dataset. Reported metrics included areas under the receiver operating characteristic curves (AUC) and balanced accuracy. Decision curve analysis for stratifying patients for surgery was performed in the testing dataset. A decision algorithm was built by combining consensus radiological readings of Bosniak categories and radiomics-based risks.
Results
A total of 149 CRL (139 patients; 65 years 56–72) were included in the training dataset—35
Bosniak(B)-IIF
(8.6% malignancy), 23
B-III
(43.5%), and 23
B-IV
(87.0%)—and 50 CRL (46 patients; 61 years 51–68) in the testing dataset—12
B-IIF
(8.3%), 10
B-III
(60.0%), and 9
B-IV
(100%). The machine learning model achieved high diagnostic performance in predicting malignancy in the testing dataset (AUC = 0.96; balanced accuracy = 94%). There was a net benefit across threshold probabilities in using the clinical decision algorithm over management guidelines based on Bosniak categories.
Conclusion
CT-based radiomics modeling accurately distinguished benign from malignant CRL, outperforming the Bosniak classification. The decision algorithm best stratified lesions for surgery and active surveillance.
Key Points
•
The radiomics model achieved excellent diagnostic performance in identifying malignant cystic renal lesions in an independent testing dataset (AUC = 0.96)
.
•
The machine learning–enhanced decision algorithm outperformed the management guidelines based on the Bosniak classification for stratifying patients to surgical ablation or active surveillance
.
Objectives To evaluate the feasibility of dynamic contrast enhanced magnetic resonance imaging (DCE MRI) and measure values of in vivo placental perfusion in women. Methods This study was part of the ...Placentimage trial (NCT01092949). Gadolinium-chelate (Gd) enhanced dynamic MRI was performed two days before termination of pregnancies at 16 to 34 weeks gestational age (GA). Quantitative analysis was performed using one-compartment intravascular modeling. DCE perfusion parameters were analyzed across GA and were compared in IUGR and AGA fetuses. Results 134 patients were enrolled. After quality control check, 62 DCE MRI were analyzed including 48 and 14 pregnancies with normal and abnormal karyotypes, respectively. Mean placental blood flow was 129±61 mL/min/100ml in cases with normal karyotypes. Fetuses affected by IUGR (n = 13) showed significantly lower total placental blood flow values than AGA fetuses (n = 35) (F .sub.total = 122±88 mL/min versus 259±34 mL/min, p = 0.002). DCE perfusion parameters showed a linear correlation with GA. Conclusions Measuring placental perfusion in vivo is possible using DCE MRI. Although this study has many limitations it gives us the first DCE MRI values that provide a potential standard for future research into placental perfusion methods and suggests that placental functional parameters are altered in IUGR pregnancies.
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