Filipe Caseiro-Alves

Rectal Cancer: Assessment of Complete Response to Preoperative Combined Radiation Therapy with Chemotherapy--Conventional MR Volumetry versus Diffusion-weighted MR Imaging.

PURPOSEnTo determine diagnostic performance of diffusion-weighted (DW) magnetic resonance (MR) imaging for assessment of complete tumor response (CR) after combined radiation therapy with chemotherapy (CRT) in patients with locally advanced rectal cancer (LARC) by means of volumetric signal intensity measurements and apparent diffusion coefficient (ADC) measurements and to compare the performance of DW imaging with that of T2-weighted MR volumetry.nnnMATERIALS AND METHODSnA retrospective analysis of 50 patients with LARC, for whom clinical and imaging data were retrieved from a previous imaging study approved by the local institutional ethical committee and for which all patients provided informed consent, was conducted. Patients underwent pre- and post-CRT standard T2-weighted MR and DW MR. Two independent readers placed free-hand regions of interest (ROIs) in each tumor-containing section on both data sets to determine pre- and post-CRT tumor volumes and tumor volume reduction rates (volume). ROIs were copied to an ADC map to calculate tumor ADCs. Histopathologic findings were the standard of reference. Receiver operating characteristic (ROC) curves were generated to compare performance of T2-weighted and DW MR volumetry and ADC. The intraclass correlation coefficient (ICC) was used to evaluate interobserver variability and the correlation between T2-weighted and DW MR volumetry.nnnRESULTSnAreas under the ROC curve (AUCs) for identification of a CR that was based on pre-CRT volume, post-CRT volume, and volume, respectively, were 0.57, 0.70, and 0.84 for T2-weighted MR versus 0.63, 0.93, and 0.92 for DW MR volumetry (P = .15, .02, .42). Pre- and post-CRT ADC and ADC AUCs were 0.55, 0.54, and 0.51, respectively. Interobserver agreement was excellent for all pre-CRT measurements (ICC, 0.91-0.96) versus good (ICC, 0.61-0.79) for post-CRT measurements. ICC between T2-weighted and DW MR volumetry was excellent (0.97) for pre-CRT measurements versus fair (0.25) for post-CRT measurements.nnnCONCLUSIONnPost-CRT DW MR volumetry provided high diagnostic performance in assessing CR and was significantly more accurate than T2-weighted MR volumetry. Post-CRT DW MR was equally as accurate as volume measurements of both T2-weighted and DW MR. Pre-CRT volumetry and ADC were not reliable.

Magnetic resonance imaging for the clinical management of rectal cancer patients: recommendations from the 2012 European Society of Gastrointestinal and Abdominal Radiology (ESGAR) consensus meeting

AbstractObjectivesTo develop guidelines describing a standardised approach regarding the acquisition, interpretation and reporting of magnetic resonance imaging (MRI) for clinical staging and restaging of rectal cancer.MethodsA consensus meeting of 14 abdominal imaging experts from the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) was conducted following the RAND-UCLA Appropriateness Method. Two independent (non-voting) chairs facilitated the meeting. Two hundred and thirty-six items were scored by participants for appropriateness and classified subsequently as appropriate or inappropriate (defined by ≥ 80xa0% consensus) or uncertain (defined by <xa080xa0% consensus). Items not reaching 80xa0% consensus were noted.ResultsConsensus was reached for 88xa0% of items: recommendations regarding hardware, patient preparation, imaging sequences, angulation, criteria for MRI assessment and MRI reporting were constructed from these.ConclusionsThese expert consensus recommendations can be used as clinical guidelines for primary staging and restaging of rectal cancer using MRI.Key Points• These guidelines recommend standardised imaging for staging and restaging of rectal cancer.n • The guidelines were constructed through consensus amongst 14 abdominal imaging experts.n • Consensus was reached by in 88xa0% of 236 items discussed.

Diffusion-weighted MRI in rectal cancer: Apparent diffusion coefficient as a potential noninvasive marker of tumor aggressiveness

To assess the value of diffusion‐weighted MR imaging (DWI) as a potential noninvasive marker of tumor aggressiveness in rectal cancer, by analyzing the relationship between tumoral apparent diffusion coefficient (ADC) values and MRI and histological prognostic parameters.

Gastroenterologic and Radiologic Approach to Obscure Gastrointestinal Bleeding: How, Why, and When?

Gastrointestinal (GI) bleeding is a common clinical condition that is increasingly seen in an aging population and frequently requires hospitalization and intervention, with significant morbidity and mortality. Obscure GI bleeding (OGIB) is defined as loss of blood with no source identified after upper endoscopy and colonoscopy. Whether an obscure site of bleeding is clinically evident or silent, it constitutes a diagnostic and therapeutic challenge for the clinician. Gastroenterology and radiology provide the essential diagnostic tools used to evaluate suspected OGIB, each with its strengths and weaknesses. Small bowel series and conventional enteroclysis have a limited role in OGIB. Computed tomographic (CT) enterography and CT enteroclysis are noninvasive techniques with promising results in evaluation of small bowel disease and silent OGIB. CT angiography is a useful triaging tool for diagnosing or excluding active GI hemorrhage, localizing the site of bleeding, and guiding subsequent treatment. Tagged red blood cell scanning is the most sensitive technique for detection of active GI bleeding and allows imaging over a prolonged period, making it useful for detecting intermittent bleeding. Capsule endoscopy has emerged as an important tool for investigating OGIB, but it may soon have competition from double-balloon enteroscopy, a diagnostic technique that can also facilitate therapy.

USPIO-enhanced magnetic resonance imaging for nodal staging in patients with head and neck cancer.

To determine the accuracy of ultrasmall superparamagnetic iron oxide (USPIO)‐enhanced magnetic resonance imaging (MRI) for nodal staging in patients with head and neck cancer.

Congenital Cystic Lesions of the Biliary Tree

OBJECTIVEnThe purpose of this essay is to illustrate the imaging findings of congenital cystic lesions of the biliary tract.nnnCONCLUSIONnCongenital cystic lesions of the biliary tract include ductal plate malformations and choledochal cysts and can be recognized with characteristic imaging findings and basic knowledge of the embryologic development of the biliary tree.

Diffusion-weighted imaging of the liver: usefulness of ADC values in the differential diagnosis of focal lesions and effect of ROI methods on ADC measurements

ObjectBy measuring the apparent diffusion coefficient (ADC) of liver parenchyma and focal hepatic lesions (FHL) we proposed to investigate the utility of ADC in the differential diagnosis of hepatic disease and to determine the influence of region of interest (ROI) characteristics in those measurements.Materials and methodsNinety-three patients with at least one supracentimetric FHL, or parenchymal abnormality, were retrospectively evaluated. Diagnosis was based on histopathologic data or, alternatively, on a combination of consensus between imaging methods and 24xa0months of follow-up. Ninety lesions were evaluated with respiratory-triggered diffusion-weighted imaging (b values: 50 and 700xa0s/mm2): 14 hepatocellular carcinomas, 18 metastases, 10 focal nodular hyperplasias, four adenomas, 30 hemangiomas and 14 cysts. ADC of hepatic parenchyma was measured by placing ROIs in four different segments, and in FHLs by using three circular 1xa0cm2 ROIs and one ROI encompassing the full lesion. Data was statistically analyzed (pxa0<xa00.05 considered significant), and a receiver operating characteristic curve was assessed to evaluate the accuracy for the diagnosis of malignancy.ResultsOur measurements showed that parenchyma ADC was significantly higher in segment II and that ADCs of malignant lesions were significantly lower than those of benign lesions (pxa0<xa00.001). There was significant overlap between benign solid lesions and malignant lesions and the area under the curve for malignancy was 0.939 (sensitivity 89.7xa0%, specificity 90.6xa0%), using a cutoff of 1.43xa0×xa010−3 mm2/s. No significant difference was found between ROIs of different characteristics.ConclusionADC measurements can help to characterize FHLs and differentiate normal from pathological parenchyma. Any ROI above 1xa0cm2 can provide accurate ADC measurements in homogenous lesions.

Correspondence between left ventricular 17 myocardial segments and coronary anatomy obtained by multi-detector computed tomography: an ex vivo contribution

PurposeThe aim of this study was to investigate the correspondence between the coronary arterial anatomy and the supplied myocardium based on the proposed American Heart Association (AHA) 17-segment model.MethodsSix human cadaveric hearts without signs of infarct were selectively injected with colored contrasted gelatin in the three major coronary arteries. After injection, the hearts were scanned by computed tomography (64-detector scanner LightSpeed VCT, GE Healthcare) with a collimation of 64xa0×xa00.625xa0mm. Reconstructed image data were analyzed in order to evaluate the blood supply of each myocardial segment.ResultsCoronary artery territory varies due to anatomy variations. Left anterior descending coronary artery (LAD) was the main vessel responsible for the myocardium blood supply in 11 segments. LAD contributed to the blood supply of all apical segments. Left circumflex (LCx) was the main coronary artery for the infero-anterior wall. Right coronary artery (RCA) contributed in all hearts for the blood supply of infero-septal segments. There was an important overlap between LAD and RCA territories at the infero-septal region and between LAD and LCx territories at the antero-lateral region.ConclusionsIn our experiment, LAD territory was larger than the AHA-proposed 17-segment model. The most specific segments were located at the anterior wall and supplied exclusively by LAD. No specific segment could be exclusively attributed to RCA or to LCx. Sometimes, LCx can be the most important artery for the blood supply of the inferior wall even if the origin of the posterior descending artery is the RCA.

Normal vascular and biliary hepatic anatomy: 3D demonstration by multidetector CT

Due to constant innovations in radiological and surgical techniques, more accurate results are expected in the diagnostic and therapeutic procedures related to hepatic pathology. The aim of this work was to demonstrate the normal hepatic vascular and biliary anatomy using cadaveric livers and CT scans of the affected livers. Furthermore, using the CT scans, the authors intended to illustrate the most common morphological variations of the vascular and biliary anatomy. Four human cadaveric livers were injected with colored silicone mixed with radiological contrast solution in the common bile duct, in the proper hepatic artery, in the portal vein and in the inferior vena cava near the ostia of the hepatic veins (only one of these structures was injected in each liver). After obtaining the CT scans, 3D rendered models were created, which demonstrated the normal hepatic anatomy of the vascular and biliary structures. The International Anatomical Nomenclature was used for their classification (based on Couinaud’s work). The 3D rendered CT models were also modified to illustrate the most common normal variations of the hepatic anatomy (found in the literature).

One-shot diagnostic and prognostic assessment in intermediate- to high-risk acute pulmonary embolism: The role of multidetector computed tomography

INTRODUCTIONnContrast-enhanced multidetector computed tomography (MDCT) is useful for the diagnosis of pulmonary embolism (PE). However, current guidelines do not support its use for risk assessment in acute PE patients.nnnOBJECTIVESnWe compared the prognostic impact of MDCT-derived indices regarding medium-term mortality in a population of intermediate- to high-risk PE patients, mostly treated by thrombolysis.nnnMETHODSnThirty-nine consecutive patients admitted to an intensive care unit with acute PE were studied. All patients had a pulmonary MDCT on admission to the emergency room as part of the diagnostic algorithm. We assessed the following MDCT variables: right ventricular/left ventricular diameter (RV/LV) ratio, arterial obstruction index, pulmonary artery-to-aorta diameter ratio and azygos vein diameter. A 33-month follow-up was performed.nnnRESULTSnMean age was 59.1±19.6 years, with 80% of patients receiving thrombolysis. Follow-up all-cause mortality was 12.8%. Of the MDCT-derived variables, only the RV/LV ratio had significant predictive value, being higher in patients who suffered the endpoint (1.6±0.5 vs. 1.9±0.4, p=0.046). Patients with an RV/LV ratio ≥1.8 had 11-fold higher medium-term all-cause mortality (3.8% vs. 38.8%, p<0.001). Regarding this endpoint, the c-statistic was 0.78 (95% CI, 0.60-0.96) for RV/LV ratio and calibration was good (goodness-of-fit p=0.594). No other radiological index was predictive of mortality.nnnCONCLUSIONSnMDCT gives the possibility, in a single imaging procedure, of diagnosing and assessing the prognosis of patients with intermediate- to high-risk PE. Although further studies are needed, the simple-to-calculate RV/LV ratio has good discrimination and calibration for predicting poorer outcomes in patients with acute PE.