Resistive intrarenal index: myth or reality?

In renal diagnosis, the B-mode ultrasound is used to provide an accurate study of the renal morphology, whereas the colour and power Doppler are of strategic importance in providing qualitative and quantitative information about the renal vasculature, which can also be obtained through the assessment of the resistive index (RI). To date, this is one of the most sensitive parameters in the study of kidney diseases and allows us to quantify the changes in renal plasma flow. If a proper Doppler ultrasound examination is carried out and a critical analysis of the values obtained is performed, the RI measurement at the interlobar artery level has been suggested in the differential diagnosis between nephropathies. The aim of this review is to highlight the pathological conditions in which the study of intrarenal RI provides useful information about the pathophysiology of renal diseases in both the native and the transplanted kidneys.Renal ultrasonography has acquired a strategic importance in the early detection of several renal diseases thanks to its non-invasivity, low cost, reliability and high sensitivity. The B-mode ultrasound is a widely used technique for the study of kidney morphology, including renal pelvis, to provide information on parenchymal echogenicity and to detect space-occupying lesions.The characteristic ultrasonographic pattern in chronic kidney disease (small kidneys, reduced parenchymal thickness and detection of cysts) allows a simple and accurate diagnosis of this pathological condition. On the other hand, the diagnostic validity of the B-mode ultrasound in the detection of acute renal disease is still under debate because of the lack of sensitivity and specificity of the commonly used parameters such as the increase of renal size and the reduction of the parenchymal echogenicity.The advantage of using Doppler ultrasound (DUS) lies in its ability in detecting not only renal morphological abnormalities but also functional ones; colour Doppler, power DUS and spectral analysis provide qualitative and quantitative haemodynamic information about the intrarenal and extrarenal vasculature highlighting changes in the renal blood flow.The measure of renal resistive index (RI) or Pourcelot index is one of the most sensitive parameters in the study of disease-derived alterations of renal plasma flow.The aim of this review is to evaluate the significance of the renal RI as a non-invasive marker of renal histological damage in several pathological conditions (

PET imaging of aortic atherosclerosis: Is combined imaging of plaque anatomy and function an amaranthine quest or conceivable reality?

Traditionally, blood vessels have been studied using contrast luminography to determine the site, extent and severity of luminal compromise by atherosclerotic deposits. Similar anatomical data can now be acquired non-invasively using ultrasound, computed tomography or magnetic resonance imaging. Plaque stability is an important determinant of subsequent vascular events and currently functional data on the stability of plaque is less well provided by these methods. The search for non-invasive techniques to image combined plaque anatomy and function has been pursued with visionary anticipation. This expectation may soon be realised as imaging with radionuclide-labelled atheroma-targeted contrast agents has demonstrated that plaque functional characteristics can now be shown. Increasingly positron emission tomography/computed tomography (PET/CT) imaging with ¹⁸F fluorodexoyglucose (FDG) and other radionuclides is being used to determine culprit plaques in complex clinically scenarios. Clinically, this information may prove extremely valuable in the assessment of stable and unstable patients and its use in prime time medical practice is eagerly awaited. We will discuss the current clinical applications of functional atheroma imaging in the aorta and highlight the promising preclinical data on novel image biomarkers of plaque instability. If clinical science is able to successfully translate these advances in vascular imaging from the bench to the bedside, a new paradigm will be achieved in cardiovascular diagnostics.     

Siderotic nodules at MR imaging: regenerative or dysplastic?

OBJECTIVE: To determine if iron containing "siderotic" nodules detected at magnetic resonance (MR) imaging are regenerative (RN) or dysplastic (DN) and to attempt to identify features that may distinguish them. MATERIAL AND METHODS: MR imaging (1.5 T) was performed on 77 cirrhotic patients who underwent orthotopic liver transplantation within 0-117 days (mean 30 days) of MR imaging. Two readers retrospectively evaluated breath-hold gradient-echo pulse sequences (echo time > or =9.0 ms, flip angle < or =45 degrees) for the presence of hypointense nodules, which were classified as micronodular (< or =3 mm), macronodular (>3 mm), or mixed. Nodule distribution was classified as focal (<5), scattered (5-20), or diffuse (>20) per slice. Thin section pathologic correlation was available in all cases, and Prussian blue iron stains were performed. RESULTS: Of 35 patients with pathologically proven siderotic nodules, 10 (29%) had at least 2 siderotic DN. MR detected siderotic nodules in 10 of 10 (100%) patients with siderotic DN and RN, and in 18 of 25 patients (72%) with siderotic RN only. CONCLUSION: Siderotic RN cannot be reliably distinguished from siderotic DN with MR imaging, and therefore the widely used term "siderotic regenerative nodule" should be avoided and replaced by "siderotic nodule."     

Low-dose chest CT with millimetric thin slices: myth or reality?

PURPOSE: To evaluate the diagnostic accuracy of millimetric thin slices low dose chest CT. MATERIALS AND METHODS: Forty one patients underwent a chest CT thin slices (1 mm every 10 mm) exploration using both a 170 milliamperage and a low dose acquisition using 80 mA. The examination were read by 2 senior radiologists specialized in chest imaging without knowledge of acquisition parameters and in a random order. A statistical analysis of interobserver agreement was performed using Kappa analysis. Doses of both acquisition were estimated by compagning the dose length product calculated by the CT software and be using a simulation software. RESULTS: Excellent interobserver and intermodalities agreements were found. A 53% decrease in dose was estimated with the low dose modality compare to the normal dose. CONCLUSION: Low dose thin slice chest CT using 80 mA has a similar diagnosis accuracy as standard dose thin slice chest CT and delivers half dose of irradiation.     

MR imaging findings in spinal infections: rules or myths?

PURPOSE: To systematically evaluate magnetic resonance (MR) imaging findings described as being indicative of spinal infection in patients with proven spinal infection. MATERIALS AND METHODS: Contrast material-enhanced spinal MR images obtained in 46 consecutive patients (22 women, 24 men; mean age, 58.2 years) with culture or histologic examination results positive for spinal infection were systematically evaluated by two observers. Tuberculous and postoperative infections were excluded. Disk signal intensity and disk height, presence of the nuclear cleft, vertebral signal intensity alterations, endplate erosions on T1-weighted MR images, and presence of paraspinal or epidural inflammation were evaluated. Patient charts and surgical reports were reviewed. RESULTS: In the 44 patients with disk infection, MR imaging criteria with good to excellent sensitivity included presence of paraspinal or epidural inflammation (n = 43, 97.7% sensitivity), disk enhancement (n = 42, 95.4% sensitivity), hyperintensity or fluid-equivalent disk signal intensity on T2-weighted MR images (n = 41, 93.2% sensitivity), and erosion or destruction of at least one vertebral endplate (n = 37, 84.1% sensitivity). Effacement of the nuclear cleft was only applicable in 18 patients (n = 15, 83.3% sensitivity). Criteria with low sensitivity included decreased height of the intervertebral space (n = 23, 52.3% sensitivity) and disk hypointensity on T1-weighted MR images (n = 13, 29.5% sensitivity). Involvement of several spinal levels occurred in seven (16%) patients. Other spinal infections included isolated vertebral osteomyelitis (n = 1) and primary epidural abscess (n = 1). CONCLUSION: Most MR imaging criteria commonly used to diagnose disk infections offer good to excellent sensitivity. In atypical manifestations of proven spinal infections, however, some of the classically described MR imaging criteria may not be observed.     

Liposarcoma or lipoma: Does genetics change classic imaging criteria?

Differentiating benign from malignant fatty tumours has always been very difficult for both radiologists and pathologists. Cytogenetic and molecular genetic analyses provide complementary tools for differentiating soft tissue tumours.Our objective was to compare imaging criteria of malignancy with a new diagnostic gold standard, namely, pathological analysis combined with cytogenetic and molecular genetic analyses. Nineteen patients with a fatty tumour were included. All had computed tomography and/or magnetic resonance imaging examination before any biopsy or surgery. All had histopathological and cytogenetic and/or molecular genetic analyses. The imaging diagnosis of benign or malignant lesions was accurate in 15 cases, with 4 false positives for malignancy. Erroneous criteria were a large size (4 cases), and a mass that was not purely fatty.In conclusion, the main pitfall for a false positive radiological diagnosis of liposarcoma is certainly a large-sized tumour. Cytogenetic and molecular genetic analyses contribute to the diagnosis and can be performed at the same time with a core biopsy.     

Prostate MR imaging at high-field strength: evolution or revolution?

As 3 T MR scanners become more available, body imaging at high field strength is becoming the subject of intensive research. However, little has been published on prostate imaging at 3 T. Will high-field imaging dramatically increase our ability to depict and stage prostate cancer? This paper will address this question by reviewing the advantages and drawbacks of body imaging at 3 T and the current limitations of prostate imaging at 1.5 T, and by detailing the preliminary results of prostate 3 T MRI. Even if slight adjustments of imaging protocols are necessary for taking into account the changes in T1 and T2 relaxation times at 3 T, tissue contrast in T2-weighted (T2w) imaging seems similar at 1.5 T and 3 T. Therefore, significant improvement in cancer depiction in T2w imaging is not expected. However, increased spatial resolution due to increased signal-to-noise ratio (SNR) may improve the detection of minimal capsular invasion. Higher field strength should provide increased spectral and spatial resolution for spectroscopic imaging, but new pulse sequences will have to be designed for overcoming field inhomogeneities and citrate J-modulation issues. Finally, dynamic contrast-enhanced MRI is the method of imaging that is the most likely to benefit from the increased SNR, with a significantly better trade-off between temporal and spatial resolution.     

Imaging in multiple myeloma: Computed tomography or magnetic resonance imaging?

Multiple myeloma (MM) is the second most common type of hematological disease with its incidence rising in the elderly. In MM, the extent of the bone disease increases both morbidity and mortality. The detection of lytic bone lesions on imaging, especially computerized tomography (CT) and magnetic resonance imaging (MRI) is crucial to separate asymptomatic from symptomatic MM patients even when no clinical symptoms are present. Although radiology is essential in the staging and management of patients with MM there is still high variability in the choice between MRI and CT. In addition, there is still suboptimal agreement among readers. The potential of medical imaging in MM is largely under-evaluated: artificial intelligence, radiomics and new quantitative methods to report CT and MRI will improve imaging usage.