L. Flors

Ventilation-based segmentation of the lungs using hyperpolarized 3He MRI

To develop an automated segmentation method to differentiate the ventilated lung volume on 3He magnetic resonance imaging (MRI).

Endoleak Detection After Endovascular Repair of Thoracic Aortic Aneurysm Using Dual-Source Dual-Energy CT: Suitable Scanning Protocols and Potential Radiation Dose Reduction

OBJECTIVEnThe objective of our study was to evaluate the diagnostic performance of dual-source dual-energy CT (DECT) in the detection of endoleaks after thoracic endovascular aortic repair for thoracic aortic aneurysm and to investigate if a double-phase (arterial and dual-energy late delayed phase) or a single-phase (dual-energy late delayed phase) acquisition can replace the standard triphasic protocol.nnnMATERIALS AND METHODSnAll DECT examinations performed for evaluation after thoracic endovascular aortic repair during a 30-month period were retrospectively reviewed. An initial single-source unenhanced acquisition was followed by a single-source arterial phase acquisition and a dual-energy 300-second late delayed phase acquisition. Virtual noncontrast images were generated from the dual-energy acquisition. Two independent and blinded radiologists evaluated the cases during three reading sessions: session A (triphasic protocol: standard unenhanced, arterial phase, and late delayed phase), session B (virtual noncontrast and late delayed phase), and session C (virtual noncontrast, arterial phase, and late delayed phase). The diagnostic accuracies of sessions B and C were calculated using session A as the reference standard. Contrast-to-noise ratios and effective radiation doses were calculated.nnnRESULTSnForty-eight patients (mean age, 66 years; age range, 19-84 years) underwent 74 triple-phase CT examinations. The single-phase studies (session B) were characterized by 85.7% sensitivity, 100% specificity, 100% negative predictive value (NPV), and 94.6% positive predictive value (PPV). The dual-phase study (session C) revealed 100% sensitivity, 100% specificity, 100% NPV, and 100% PPV. The use of the dual-phase protocol and single-phase protocol resulted in a radiation exposure reduction of 19.5% and 64.1%, respectively.nnnCONCLUSIONnVirtual noncontrast and late delayed phase images reconstructed from a single DECT acquisition can replace the standard triphasic protocol in follow-up examinations after thoracic endovascular aortic repair, thereby providing a significant dose reduction.

Imaging Evaluation of Flow Limitations in the Iliac Arteries in Endurance Athletes: Diagnosis and Treatment Follow-Up

OBJECTIVEnThe purpose of this article is to review the role of imaging in the diagnosis, treatment, and follow-up of patients with sport-related flow limitations in the iliac arteries.nnnCONCLUSIONnEndurance athletes can develop flow restriction during exercise because of endofibrosis or kinking of the iliac arteries. Knowledge of this entity and the use of appropriate imaging techniques are crucial for diagnosis. Imaging plays an important role in the assessment of the underlying lesion and its location as well as in posttreatment follow-up.

Dental Flat Panel Conebeam CT in the Evaluation of Patients with Inflammatory Sinonasal Disease: Diagnostic Efficacy and Radiation Dose Savings

BACKGROUND AND PURPOSE: CT is the imaging modality of choice to study the paranasal sinuses; unfortunately, it involves significant radiation dose. Our aim was to assess the diagnostic validity, image quality, and radiation-dose savings of dental conebeam CT in the evaluation of patients with suspected inflammatory disorders of the paranasal sinuses. MATERIAL AND METHODS: We prospectively studied 40 patients with suspected inflammatory disorders of the sinuses with dental conebeam CT and standard CT. Two radiologists analyzed the images independently, blinded to clinical information. The image quality of both techniques and the diagnostic validity of dental conebeam CT compared with the reference standard CT were assessed by using 3 different scoring systems. Image noise, signal-to-noise ratio, and contrast-to-noise ratio were calculated for both techniques. The absorbed radiation dose to the lenses and thyroid and parotid glands was measured by using a phantom and dosimeter chips. The effective radiation dose for CT was calculated. RESULTS: All dental conebeam CT scans were judged of diagnostic quality. Compared with CT, the conebeam CT image noise was 37.3% higher (P < .001) and the SNR of the bone was 75% lower (P < .001). The effective dose of our conebeam CT protocol was 23 μSv. Compared with CT, the absorbed radiation dose to the lenses and parotid and thyroid glands with conebeam CT was 4%, 7.8%, and 7.3% of the dose delivered to the same organs by conventional CT (P < .001). CONCLUSIONS: Dental conebeam CT is a valid imaging procedure for the evaluation of patients with inflammatory sinonasal disorders.

RM con gases hiperpolarizados: Nuevas perspectivas en el estudio de enfermedades pulmonares

Hyperpolarized (HP) gases are a new class of contrast agents that permit to obtain high temporal and spatial resolution magnetic resonance images (MRI) of the lung airspaces. HP gas MRI has become important research tool not only for morphological and functional evaluation of normal pulmonary physiology but also for regional quantification of pathologic changes occurring in several lung diseases. The purpose of this work is to provide an introduction to MRI using HP noble gases, describing both the basic principles of the technique and the new information about lung disease provided by clinical studies with this method. The applications of the technique in normal subjects, smoking related lung disease, asthma, and cystic fibrosis are reviewed.

Ten Frequently Asked Questions About MRI Evaluation of Soft-Tissue Vascular Anomalies

OBJECTIVEnThe objective of this article was to address 10 frequently asked questions that radiologists face when planning, performing, and interpreting an MRI study in a patient with a soft-tissue vascular anomaly.nnnCONCLUSIONnMRI permits a comprehensive assessment of vascular anomalies. It is important for radiologists to be familiar with the classification and correct nomenclature of vascular anomalies as well as the MRI protocol and distinct imaging findings of the different vascular malformations and tumors.

Detection of parathyroid adenomas using a monophasic dual-energy computed tomography acquisition: diagnostic performance and potential radiation dose reduction

IntroductionThe aims of the study were to compare the diagnostic performance of a combination of virtual non-contrast (VNC) images and arterial images obtained from a single-phase dual-energy CT (DECT) acquisition and standard non-contrast and arterial images from a biphasic protocol and to study the potential radiation dose reduction of the former approach.MethodsAll DECT examinations performed for evaluation of parathyroid adenomas during a 13-month period were retrospectively reviewed. An initial single-energy unenhanced acquisition was followed by a dual-energy arterial phase acquisition. “Virtual non-contrast images” were generated from the dual-energy acquisition. Two independent and blinded radiologists evaluated three different sets of images during three reading sessions: single arterial phase, single-phase DECT (virtual non-contrast and arterial phase), and standard biphasic protocol (true non-contrast and arterial phase). The accuracy of interpretation in lateralizing an adenoma to the side of the neck and localizing it to a quadrant in the neck was evaluated.ResultsSixty patients (mean age, 65.5xa0years; age range, 38–87xa0years) were included in the study. The lateralization and localization accuracy, sensitivity, and positive predicted value (PPV) and negative predicted value (NPV) of the different image datasets were comparable. The combination of VNC and arterial images was more specific than arterial images alone to lateralize a parathyroid lesion (ORxa0=xa01.93, pxa0=xa00.043). The use of the single-phase protocol resulted in a calculated radiation exposure reduction of 52.8xa0%.ConclusionsVirtual non-contrast and arterial images from a single DECT acquisition showed similar diagnostic accuracy than a biphasic protocol, providing a significant dose reduction.

Earlier seizure onset and longer epilepsy duration correlate with the degree of temporal hypometabolism in patients with mesial temporal lobe sclerosis

OBJECTIVEnTo study the relationship of glucose metabolism and volume of the temporal lobes with age at epilepsy onset, epilepsy duration, and seizure frequency in patients with mesial temporal sclerosis (MTS).nnnMETHODSnWe evaluated the pre-surgical 18F-fluoro-deoxyglucose (FDG) positron emission tomography (PET) and magnetic resonance imaging (MRI) of 18 patients with epilepsy and MRI findings of MTS, who were seizure-free for at least 2-years after temporal lobectomy. We calculated the volume of the hippocampi and amygdalae on MRI. On PET we studied their mean standard uptake values (SUV), and relative metabolic activity as compared to normal subjects in terms of Z-scores. We compared the PET and MRI metrics in the bilateral structures using the Wilcoxon sign rank test. We studied the relationship between the imaging metrics and age of epilepsy onset, epilepsy duration, and seizure frequency via Spearman correlation analyses.nnnRESULTSnYounger age at onset correlated with decreased hippocampal glucose metabolism (rs=0.64, p=0.008). Longer epilepsy duration correlated with decreased hippocampal glucose metabolism (rs=-0.55, p=0.024). There was no correlation between age at onset of epilepsy, epilepsy duration, or seizure frequency and volumetrics. Z-score in the sclerotic hippocampus (-3.51±2.2vs -0.7±1.7) and amygdala (-3.26±2.3 vs -0.68±1.8) was smaller than the contralateral (p<0.001). The diseased hippocampus (2.84±0.49 vs 3.52±0.4ml) and ipsilateral amygdala (1.49±0.24 vs 1.72±0.3ml) were significantly smaller than the contralateral (p<0.02).nnnSIGNIFICANCEnEarlier epilepsy onset correlated with hippocampal hypometabolism. Longer epilepsy duration correlated with amygdalar hypometabolism suggesting an ongoing progressive disease in MTLE.

Malformaciones vasculares y tumores de partes blandas. Parte 1: clasificación, papel de las pruebas imagen y lesiones de alto flujo

Vascular malformations and tumors, also known as vascular anomalies, comprise an extensive variety of lesions involving all parts of the body. Knowledge of their classification and imaging characteristics is paramount. Whereas hemangiomas are benign vascular tumors, characterized by cellular proliferation and hyperplasia; vascular malformations are not real tumors and characteristically exhibit normal endothelial turnover. Vascular malformations are classified according to the predominant vascular channel as arterial, capillary, venous, lymphatic, or mixed. Ultrasound and MRI are the main imaging modalities used in the diagnosis and classification of the vascular anomalies. In this series of two articles we review the classification of vascular anomalies, describe the role of imaging, summarize their distinctive histopathogenic, clinical and imaging features, and discuss the treatment options. On the first article we discuss the high-flow lesions, whereas the slow-flow lesions will be reviewed on the second. Complex syndromes with associated vascular tumors and malformations will be also presented.

Malformaciones vasculares y tumores de partes blandas. Parte 2: lesiones de bajo flujo

Vascular malformations and tumors, also known as vascular anomalies, comprise an extensive variety of lesions involving all parts of the body. Due to a lack of a complete understanding of the origin and histopathology of such lesions, this field has been traditionally obscured by the use of an unclear nomenclature. Knowledge of the classification and clinical and imaging characteristics of this group of lesions is paramount when managing these patients. The objective of this series of two articles is to review the current classification of vascular anomalies, to describe the role of imaging in their diagnosis, to summarize their distinctive histopathologic, clinical and imaging features, and to discuss the treatment options. High-flow lesions were discussed in the first article of this series. In this second article, we will focus on low-flow lesions, including complex syndromes with associated low-flow malformations.