Marcos Paulo Ferreira Botelho

Assessment of Liver Tumor Response to Therapy: Role of Quantitative Imaging

Quantitative imaging is the analysis of retrieved numeric data from images with the goal of reducing subjective assessment. It is an increasingly important radiologic tool to assess treatment response in oncology patients. Quantification of response to therapy depends on the tumor type and method of treatment. Anatomic imaging biomarkers that quantify liver tumor response to cytotoxic therapy are based on temporal change in the size of the tumors. Anatomic biomarkers have been incorporated into the World Health Organization criteria and the Response Evaluation Criteria in Solid Tumors (RECIST) versions 1.0 and 1.1. However, the development of novel therapies with different mechanisms of action, such as antiangiogenesis or radioembolization, has required new methods for measuring response to therapy. This need has led to development of tumor- or therapy-specific guidelines such as the Modified CT Response Evaluation (Choi) Criteria for gastrointestinal stromal tumors, the European Association for Study of the Liver (EASL) criteria, and modified RECIST for hepatocellular carcinoma, among many others. The authors review the current quantification criteria used in the evaluation of treatment response in liver tumors, summarizing their indications, advantages, and disadvantages, and discuss future directions with newer methods that have the potential for assessment of treatment response. Knowledge of these quantitative methods is important to facilitate pivotal communication between oncologists and radiologists about cancer treatment, with benefit ultimately accruing to the patient.

MDCT of chest, abdomen, and pelvis using attenuation-based automated tube voltage selection in combination with iterative reconstruction: an intrapatient study of radiation dose and image quality.

OBJECTIVE The purpose of this study was intrapatient comparison of image quality and radiation dose between MDCT scans of the chest, abdomen, and pelvis obtained with attenuation-based automated kilovoltage selection and sinogram-affirmed iterative reconstruction and scans obtained with standard kilovoltage selection and a filtered backprojection image reconstruction algorithm. MATERIALS AND METHODS One hundred one oncology patients who had undergone two chest, abdominal, and pelvis CT scans within 1 year were imaged with standard tube voltage selection of 120 kVp using a filtered backprojection reconstruction algorithm (protocol 1) and with attenuation-based automated tube voltage selection using an iterative reconstruction algorithm (protocol 2). Radiation dose parameters (volumetric CT dose index [CTDIvol], dose-length product, and effective dose) as well as image noise, signal-to-noise ratio, and contrast-to-noise ratio were compared. Two independent radiologists evaluated image quality and sharpness. Student t test, Fisher exact test, and Wilcoxon signed-rank test were used for analysis. A p value less than 0.05 was considered significant. RESULTS Mean ± SD CTDIvol values were 19.9 ± 4.43 mGy and 12.53 ± 4.79 mGy for protocols 1 and 2, respectively (p < 0.0001). Effective dose was 38.2% lower on average using protocol 2 compared with protocol 1 (12.08 vs 19.55 mSv; p < 0.0001). Objective image quality parameters were significantly better in protocol 2 (p < 0.0001). Both radiologists found the overall image quality and sharpness to be similar for both protocols (p > 0.05). CONCLUSION In patients undergoing CT examination of the chest, abdomen, and pelvis, the combination of attenuation-based automated tube voltage selection with iterative reconstruction significantly reduced radiation dose parameters and maintained objective image quality when compared with standard tube voltage selection associated with filtered backprojection reconstruction.

Breath-hold imaging of the coronary arteries using Quiescent-Interval Slice-Selective (QISS) magnetic resonance angiography: pilot study at 1.5 Tesla and 3 Tesla

BackgroundCoronary magnetic resonance angiography (MRA) is usually obtained with a free-breathing navigator-gated 3D acquisition. Our aim was to develop an alternative breath-hold approach that would allow the coronary arteries to be evaluated in a much shorter time and without risk of degradation by respiratory motion artifacts. For this purpose, we implemented a breath-hold, non-contrast-enhanced, quiescent-interval slice-selective (QISS) 2D technique. Sequence performance was compared at 1.5 and 3 Tesla using both radial and Cartesian k-space trajectories.MethodsThe left coronary circulation was imaged in six healthy subjects and two patients with coronary artery disease. Breath-hold QISS was compared with T2-prepared 2D balanced steady-state free-precession (bSSFP) and free-breathing, navigator-gated 3D bSSFP.ResultsApproximately 10 2.1-mm thick slices were acquired in a single ~20-s breath-hold using two-shot QISS. QISS contrast-to-noise ratio (CNR) was 1.5-fold higher at 3 Tesla than at 1.5 Tesla. Cartesian QISS provided the best coronary-to-myocardium CNR, whereas radial QISS provided the sharpest coronary images. QISS image quality exceeded that of free-breathing 3D coronary MRA with few artifacts at either field strength. Compared with T2-prepared 2D bSSFP, multi-slice capability was not restricted by the specific absorption rate at 3 Tesla and pericardial fluid signal was better suppressed. In addition to depicting the coronary arteries, QISS could image intra-cardiac structures, pericardium, and the aortic root in arbitrary slice orientations.ConclusionsBreath-hold QISS is a simple, versatile, and time-efficient method for coronary MRA that provides excellent image quality at both 1.5 and 3 Tesla. Image quality exceeded that of free-breathing, navigator-gated 3D MRA in a much shorter scan time. QISS also allowed rapid multi-slice bright-blood, diastolic phase imaging of the heart, which may have complementary value to multi-phase cine imaging. We conclude that, with further clinical validation, QISS might provide an efficient alternative to commonly used free-breathing coronary MRA techniques.

Diagnostic Yield of Pelvic Magnetic Resonance Venography in Patients With Cryptogenic Stroke and Patent Foramen Ovale

Background and Purpose— Paradoxical embolization is frequently posited as a mechanism of ischemic stroke in patients with patent foramen ovale. Several studies have suggested that the deep lower extremity and pelvic veins might be an embolic source in cryptogenic stroke (CS) patients with patent foramen ovale. Methods— Consecutive adult patients with ischemic stroke or transient ischemic attack and a patent foramen ovale who underwent pelvic magnetic resonance venography as part of an inpatient diagnostic evaluation were included in this single-center retrospective observational study to determine pelvic and lower extremity (LE) deep venous thrombosis (DVT) prevalence in CS versus non-CS stroke subtypes. Results— Of 131 patients who met inclusion criteria, 126 (96.2%) also had LE duplex ultrasound data. DVT prevalence overall was 7.6% (95% confidence interval, 4.1–13.6), pelvic DVT 1.5% (95% confidence interval, 0.1–5.8), and LE DVT 7.1% (95% confidence interval, 3.6–13.2). One patient with a pelvic DVT also had a LE DVT. Comparing patients with CS (n=98) with non-CS subtypes (n=33), there was no significant difference in the prevalence of pelvic DVT (2.1% versus 0%, P=1), LE DVT (6.2% versus 10.3%, P=0.43), or any DVT (7.2% versus 9.1%, P=0.71). Conclusions— Among patients with ischemic stroke/transient ischemic attack and patent foramen ovale, the majority of detected DVTs were in LE veins rather than the pelvic veins and did not differ by stroke subtype. The routine inclusion of pelvic magnetic resonance venography in the diagnostic evaluation of CS warrants further prospective investigation.

Effect of radiation dose and iterative reconstruction on lung lesion conspicuity at MDCT: Does one size fit all?

OBJECTIVE To evaluate the effect of different acquisition parameters and reconstruction algorithms in lung lesions conspicuity in chest MDCT. METHODS An anthropomorphic chest phantom containing 6 models of lung disease (ground glass opacity, bronchial polyp, solid nodule, ground glass nodule, emphysema and tree-in-bud) was scanned using 80, 100 and 120 kVp, with fixed mAs ranging from 10 to 110. The scans were reconstructed using filtered back projection (FBP) and iterative reconstruction (IR) algorithms. Three blinded thoracic radiologists reviewed the images and scored lesions conspicuity and overall image quality. Image noise and radiation dose parameters were recorded. RESULTS All acquisitions with 120 kVp received a score of 3 (acceptable) or higher for overall image quality. There was no significant difference between IR and FBP within each setting for overall image quality (p>0.05), even though image noise was significantly lower using IR (p<0.0001). When comparing specific lower radiation acquisition parameters 100 kVp/10 mAs [Effective Dose (ED): 0.238 mSv] vs 120 kVp/10 mAs (ED: 0.406 mSv) vs 80 kVp/40 mAs (ED: 0.434 mSv), we observed significant difference in lesions conspicuity (p<0.02), as well as significant difference in overall image quality, independent of the reconstruction algorithm (p<0.02), with higher scores on the 120 kV/10 mAs setting. Tree-in-bud pattern, ground glass nodule and ground glass opacity required lower radiation doses to get a diagnostic score using IR when compared to FBP. CONCLUSION Designing protocols for specific lung pathologies using lower dose acquisition parameters is feasible, and by applying iterative reconstruction, radiologists may have better diagnostic confidence to evaluate some lesions in very low dose settings, preserving acceptable image quality.

Aortic Volumetry at Contrast-Enhanced Magnetic Resonance Angiography: Feasibility as a Sensitive Method for Monitoring Bicuspid Aortic Valve Aortopathy.

Objectives Bicuspid aortic valve patients can develop thoracic aortic aneurysms and therefore require serial imaging to monitor aortic growth. This study investigates the reliability of contrast-enhanced magnetic resonance angiography (CEMRA) volumetry compared with 2-dimensional diameter measurements to identify thoracic aortic aneurysm growth. Materials and Methods A retrospective, institutional review board–approved, and Health Insurance Portability and Accountability Act–compliant study was conducted on 20 bicuspid aortic valve patients (45 ± 8.9 years, 20% women) who underwent serial CEMRA with a minimum imaging follow-up of 11 months. Magnetic resonance imaging was performed at 1.5 T with electrocardiogram-gated, time-resolved CEMRA. Independent observers measured the diameter at the sinuses of Valsalva (SOVs) and mid ascending aorta (MAA) as well as ascending aorta volume between the aortic valve annulus and innominate branch. Intraobserver/interobserver coefficient of variation (COV) and intraclass correlation coefficient (ICC) were computed to assess reliability. Growth rates were calculated and assessed by Student t test (P < 0.05, significant). The diameter of maximal growth (DMG), defined as the diameter at SOV or MAA with the faster growth rate, was recorded. Results The mean time of follow-up was 2.6 ± 0.82 years. The intraobserver COV was 0.01 for SOV, 0.02 for MAA, and 0.02 for volume (interobserver COV: 0.02, 0.03, 0.04, respectively). The ICC was 0.83 for SOV, 0.86 for MAA, 0.90 for DMG, and 0.95 for volume. Average aortic measurements at baseline and (follow-up) were 42 ± 3 mm (42 ± 3 mm, P = 0.11) at SOV, 46 ± 4 mm (47 ± 4 mm, P < 0.05) at MAA, and 130 ± 23 mL (144 ± 24 mL, P < 0.05). Average size changes were 0.2 ± 0.6 mm/y (1% ± 2%) at SOV, 0.5 ± 0.8 mm/y (1% ± 2%) at MAA, 0.7 ± 0.7 mm/y (2% ± 2%) at DMG, and 6 ± 3 mL/y (4% ± 3%) with volumetry. Conclusions Three-dimensional CEMRA volumetry exhibited a larger effect when examining percentage growth, a better ICC, and a marginally lower COV. Volumetry may be more sensitive to growth and possibly less affected by error than diameter measurements.

MR imaging of iliofemoral peripheral vascular calcifications using proton density-weighted, in-phase three-dimensional stack-of-stars gradient echo

The presence of vascular calcifications helps to determine percutaneous access for interventional vascular procedures and has prognostic value for future cardiovascular events. Unlike CT, standard MRI techniques are insensitive to vascular calcifications. In this prospective study, we tested a proton density‐weighted, in‐phase (PDIP) three‐dimensional (3D) stack‐of‐stars gradient‐echo pulse sequence with approximately 1 mm3 isotropic spatial resolution at 1.5 Tesla (T) and 3T to detect iliofemoral peripheral vascular calcifications and correlated MR‐determined lesion volumes with CT angiography (CTA).

Prevalência de sinais/sintomas sugestivos de sensibilização ao látex em profissionais de saúde

JUSTIFICATIVA Y OBJETIVOS: Las referencias en la literatura sobre reacciones a los derivados del latex han aumentado significativamente en los ultimos anos. Sin embargo faltan datos de nuestro pais relativos a la prevalencia de sensibilidad al latex en los profesionales del area de la salud. El objetivo de este estudio fue el de evaluar la prevalencia de senales/sintomas sugestivos de sensibilidad al latex en profesionales del area de la salud. METODO: Despues de aprobado por el Comite de Etica, se seleccionaron individuos pertenecientes a la plantilla de la institucion: funcionarios del Sector de Limpieza, Contabilidad y Division de Enfermeria del Centro Quirurgico; Medicos de Cirugia, Ginecologia, Obstetricia, Anestesiologia, Unidad de Terapia Intensiva y Clinica Medica. Despues de recibir la informacion y consentir con la pesquisa, los individuos fueron sometidos a un cuestionario sobre: edad, sexo, categoria profesional; tipo y tiempo de contacto profesional con los derivados del latex; tipo de guante utilizado; senales/sintomas sugestivos de sensibilidad al latex dentro y fuera del ambiente hospitalario; senales/sintomas sugestivos de atopia y de alergia a alimentos. RESULTADOS: Fueron evaluados 326 cuestionarios (193 mujeres y 133 hombres, con edad entre 30 y 73 anos). Un 75% de los encuestados tenian 10 anos de profesion. La prevalencia de los senales/sintomas sugestivos de sensibilidad al latex dentro del ambiente hospitalario con relacion a los grupos compuestos por los funcionarios del Sector de Contabilidad (no expuestos a derivados del latex en el ambiente de trabajo), y el resto de los individuos (expuestos a derivados del latex en el ambiente de trabajo), evidencio una diferencia significativa (p < 0,001). El porcentaje de senales/sintomas sugestivos de sensibilidad al latex en el ambiente hospitalario fue mas alto en los individuos con mayor tiempo promedio de uso de guantes por dia. CONCLUSIONES: Ese estudio mostro una mayor prevalencia de senales/sintomas sugestivos de sensibilidad al latex entre los profesionales expuestos a los derivados del latex en ambiente hospitalario y con un mayor tiempo de contacto con guantes de cualquier tipo. De esa forma, queda muy clara la necesidad de proseguir con esa investigacion para la confirmacion en laboratorio de la sensibilidad al latex, como tambien proponer a la Institucion la adopcion de medidas de prevencion para la sensibilidad al latex. Debe haber una concientizacion de que profesionales del area de la salud constituyen una poblacion de riesgo para alergia a los derivados del latex.BACKGROUND AND OBJECTIVES In the literature, the references on adverse reactions to latex products have been significantly increasing for the last few years. However, it lacks Brazilian data regarding the prevalence of latex-related sensitization in health care workers. The objective of this study was to evaluate the prevalence of signs and symptoms suggestive of latex-related sensitization in health care workers. METHODS Upon approval by the Ethics Committee it were selected a population of subjects from the Institutions departmental workforce: the Surgical Center Cleaning, Accounting and Nursing personnel and the physicians working at the Surgery, Gynecology, Obstetrics, Anesthesiology, Intensive Care Unit and Medical Clinics. After the informed consent has been obtained, the subjects were submitted to a questionnaire on: age, gender, professional category; type and length of time in contact with latex products; type of gloves; signs/symptoms suggestive of latex-related sensitization (LS) in and out of the hospital environment; signs/symptoms suggestive of atopy and food allergy. RESULTS A total of 326 questionnaires were evaluated (193 women and 133 men, aged between 30 and 73 years old). Out of this total, 75% of interviewees had up to 10-year length of service in their professions. The prevalence of signs/symptoms suggestive of sensitization to latex in the hospital environment, between the group of employees working in the Accounting Sector (therefore not exposed to latex in the workplace) and the remaining employees (exposed to latex products in their working environment) was significantly different (p<0.001). Also, the percentage of signs/symptoms suggestive of LS in the hospital environment was higher in subjects showing higher average time of use of gloves per day. CONCLUSIONS The present study demonstrated higher prevalence of signs/symptoms suggestive of LS among those workers exposed to latex products in the hospital environment and with higher contact time with any type of gloves. Therefore, it is clear the need to proceed with this research, for laboratorial confirmation of the latex-related sensitization, as well as that a proposal be submitted to the Institution towards the adoption of preventive measures regarding latex-related sensitization issue. Also, a consensus must exist to the fact that the health care workers comprise a population in risk for allergy to latex products.

A Papillary Fibroelastoma Involving Aortic and Pulmonary Valves: Findings on Multimodality Imaging

Cardiac papillary fibroelastoma, a rare entity, is the second most common benign primary cardiac tumor. Commonly involving the cardiac valves, this entity is increasingly diagnosed using different imaging modalities. We present a rare case of simultaneous involvement of both the aortic and pulmonary valves in an asymptomatic patient who underwent different imaging modalities, including transthoracic and transesophageal echocardiography, nongated and gated computed tomography, and magnetic resonance imaging. We will discuss the imaging findings and differential diagnosis.

Optimization of reduced-dose MDCT of thoracic aorta using iterative reconstruction.

Objective To evaluate the contribution of iterative reconstruction on image quality of reduced-dose multidetector computed tomography of the thoracic aorta. Methods A torso phantom was scanned using two tube potentials (80 and 120 kVp) and five different tube currents (110, 75, 40, 20, and 10 mAs). All images were reconstructed with both filtered back projection (FBP) and iterative reconstruction. Aortic attenuation, image noise within the thoracic aorta, signal-to-noise ratio, and sharpness of the aortic wall were quantified in the phantom for the two reconstruction algorithms. Data were analyzed using paired t test. A value of P < 0.05 was considered significant. Results The aortic attenuation was similar for FBP and iterative reconstruction (P > 0.05). Image noise level was lower (P < 0.0001), and image sharpness was higher (P = 0.046) with iterative reconstruction. Signal-to-noise ratios were higher with iterative reconstruction compared with those with FBP (P < 0.0001). Signal-to-noise ratio at 80 kVp with iterative reconstruction (9.8 ± 4.4) was similar to the signal-to-noise ratio at 120 kVp with FBP (8.4 ± 3.3) (P = 0.196). Conclusions Less image noise and higher image sharpness may be achieved with iterative reconstruction in reduced-dose multidetector computed tomography of the thoracic aorta.