OBJECTIVE: To define diagnostic criteria for coronavirus disease 2019 (COVID-19) on computed tomography (CT); to study the correlation between CT and polymerase chain reaction (PCR) testing for infection with severe acute respiratory syndrome coronavirus 2; and to determine whether the extent of parenchymal involvement and the need for mechanical ventilation are associated with the CT findings and clinical characteristics of patients with COVID-19. MATERIALS AND METHODS: This was a retrospective study of 155 patients with COVID-19 treated between March and May 2020. We attempted to determine whether the CT findings correlated with age and clinical variables, as well as whether the need for mechanical ventilation correlated with the extent of the pulmonary involvement. RESULTS: On average, the patients with COVID-19 were older than were those without (mean age, 54.8 years vs. 45.5 years; p = 0.031). The most common CT finding (seen in 88.6%) was ground-glass opacity, which correlated significantly with a diagnosis of COVID-19 (p = 0.0001). The CT findings that correlated most strongly with the need for mechanical ventilation were parenchymal bands (p = 0.013), bronchial ectasia (p = 0.046), and peribronchovascular consolidations (p = 0.012). The presence of one or more comorbidities correlated significantly with more extensive parenchymal involvement (p = 0.023). For the diagnosis of COVID-19, CT had a sensitivity of 84.3%, a specificity of 36.7%, and an accuracy of 73.5% (p = 0.012 vs. PCR). CONCLUSION: The patterns of CT findings are useful for the diagnosis of COVID-19 and the evaluation of disease severity criteria. The presence of any comorbidity is associated with greater severity of COVID-19.

Keywords: Coronavirus infections/diagnostic imaging; Tomography, X-ray computed; Pneumonia, viral.

OBJECTIVE: To evaluate computed tomography (CT) findings in 23 patients with bronchial atresia. MATERIALS AND METHODS: The CT images were reviewed by two radiologists who reached decisions by consensus. We included only patients who presented with abnormalities on CT and in whom the diagnosis had been confirmed by pathological examination of the surgical specimen (if the lesion was resected). The CT scans were assessed in order to identify the main findings and to map the distribution of the lesions (i.e., to determine whether the pulmonary involvement was unilateral or bilateral). RESULTS: The main CT finding was the combination of bronchocele and hyperinflation of the distal lung. That combination was observed in all of the patients. The lesions were unilateral in all 23 cases, being seen predominantly in the left upper lobe, followed by the right lower lobe, right upper lobe, middle lobe, and left lower lobe. CONCLUSION: The diagnosis of bronchial atresia can be reliably made on the basis of a finding of bronchocele accompanied by hyperinflation of the adjacent lung parenchyma.

Keywords: Bronchi/abnormalities; Congenital abnormalities; Tomography, X-ray computed.

OBJECTIVE: To investigate long-term results of biliary biopsy performed with transluminal forceps in the setting of metastatic biliary involvement. MATERIALS AND METHODS: Between September 2014 and June 2019, 25 patients—18 males (72%)—with a mean age of 65 ± 15 years, underwent 26 biliary biopsy procedures with a dedicated forceps system. All patients presented with obstructive jaundice that was suspected of being malignant and underwent pre-procedural magnetic resonance cholangiopancreatography. The biopsies were performed during percutaneous placement of an internal-external biliary drainage catheter, under fluoroscopic guidance. RESULTS: The technical success rate was 96% (corresponding to 25 of the 26 procedures). The histological diagnosis was inflammatory biliary stricture in five cases, pancreatic adenocarcinoma in six, liver metastases from colorectal cancer in eight, and hepatocellular carcinoma in three, the biliary mucosa being categorized as normal in three cases. In one case, the sample was considered insufficient and the procedure was successfully repeated, after which a diagnosis of pancreatic adenocarcinoma was made. Over a follow-up period of 6–48 months, there were five false-negative results: two findings of inflammatory biliary stricture were later identified as liver metastases from breast and gastric cancer, respectively; and all three patients in which the biliary mucosa was categorized as normal were subsequently diagnosed with metastatic hilar lymph nodes. The procedure was found to have a sensitivity of 77%, a specificity of 100%, and an overall accuracy of 80%. The complication rate was 11.5% (mild, transient hemobilia occurring in three cases). CONCLUSION: Percutaneous transluminal forceps biopsy is a safe, effective, minimally invasive procedure for histological characterization in patients presenting with obstructive jaundice due to a non-primary biliary tumor.

Keywords: Liver; Biliary tract diseases; Radiology, interventional/methods; Biopsy/methods; Fluoroscopy/methods.

OBJECTIVE: To validate the use of a three-dimensional printing system for metric and volumetric analysis of the segments of an abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: In patients scheduled to undergo endovascular AAA repair, the computed tomography angiography (CTA) measurements obtained during the preoperative assessment of the patients were compared with those obtained by computed tomography of individualized three-dimensional biomodels. RESULTS: The volumetric assessment showed a discrepancy of 3–12%, and the difference between the areas was 10–16%. CONCLUSION: Computed tomography measurements of 3D-printed biomodels of AAAs appear to be comparable to those of three-dimensional CTA measurements of the same AAAs, in terms of the metric and volumetric dimensions.

Keywords: Aortic aneurysm, abdominal/diagnostic imaging; Printing, three-dimensional; Aortic diseases; Biocompatible materials; Endovascular procedures; Blood vessel prosthesis implantation.

OBJECTIVE: To compare ultrasound images of the kidney obtained, randomly or in a controlled manner (standardizing the physical aspects of the ultrasound system), by various professionals and with different devices. MATERIALS AND METHODS: We evaluated a total of 919 images of kidneys, obtained by five professionals using two types of ultrasound systems, in 24 patients. The images were categorized into four types, by how they were acquired and processed. We compared the gray-scale median and different gray-scale ranges representative of virtual histological tissues. RESULTS: There were statistically significant differences among the five professionals, regardless of the type of ultrasound system employed, in terms of the gray-scale medians for the images obtained (p < 2.2e–16). Analyzing the four categories of images—a totally random image (without any standardization); a standardized image (with fixed values for gain, time gain control, and dynamic range); a normalized version of the random image; and a normalized version of the standardized image—we determined that the random image, even after normalization, differed quite significantly among the professionals (p = 0.006098). The analysis of the normalized version of the standardized image did not differ significantly among the professionals (p = 0.7319). CONCLUSION: Our findings indicate that a gray-scale analysis of ultrasound images of the kidney performs better when the image acquisition process is standardized and the images undergo a process of normalization.

Keywords: Diagnosis, computer-assisted; Kidney/diagnostic imaging; Ultrasonography/methods; Ultrasonography, interventional/methods; Image processing, computer-assisted/methods.

The acquisition of images with suppression of the fat signal is very useful in clinical practice and can be achieved in a variety of sequences. The Dixon technique, unlike other fat suppression techniques, allows the signal of fat to be suppressed in the postprocessing rather than during acquisition, as well as allowing the visualization of maps showing the distribution of water and fat. This review of the Dixon technique aims to illustrate the basic physical principles, to compare the technique with other magnetic resonance imaging sequences for fat suppression or fat quantification, and to describe its applications in the study of diseases of the musculoskeletal system. Many variants of the Dixon technique have been developed, providing more consistent separation of the fat and water signals, as well as allowing correction for many confounding factors. It allows homogeneous fat suppression, being able to be acquired in combination with several other sequences, as well as with different weightings. The technique also makes it possible to obtain images with and without fat suppression from a single acquisition. In addition, the Dixon technique can be used as a quantitative method, allowing the proportion of tissue fat to be determined, and, in more updated versions, can quantify tissue iron.

Keywords: Magnetic resonance imaging; Dixon technique; Fat suppression; Fat quantification; Musculoskeletal system.

Plastic and metal biliary stents can fail to function properly, such failure being due to a positioning error or to the migration, occlusion, or fracture of the stent. An obstructed biliary stent can act as a nidus, causing complications such as recurrent persistent cholangitis. It can also cause vascular complications (such as bleeding and the formation of pseudoaneurysms), perforate the liver capsule (causing biloma or abscess), or, in rare cases, cause intestinal obstruction or perforation. In this pictorial essay, we demonstrate various interventional radiology techniques for the treatment of biliary stent dysfunction in patients with obstructive biliary disease.

Keywords: Radiology, interventional; Stents; Cholestasis/therapy.

Intracranial cystic lesions are common findings on neuroimaging examinations, arachnoid cysts being the most common type of such lesions. However, various lesions of congenital, infectious, or vascular origin can present with cysts. In this pictorial essay, we illustrate the main causes of non-neoplastic intracranial cystic lesions, discussing their possible differential diagnoses as well as their most relevant imaging aspects.

Keywords: Arachnoid cysts/diagnosis; Brain/diagnostic imaging; Cysts/diagnostic imaging; Epidermal cyst/diagnostic imaging; Magnetic resonance imaging.

Although the correct diagnosis of inguinal hernias can often be made by clinical examination, there are several situations in which imaging methods represent the best option for evaluating such hernias, their content, and the possible complications. In addition, bulging of the inguinal region is not always indicative of a hernia, because other lesions, including tumors, cysts, and hematomas, also affect the region. The objective of this pictorial essay is to demonstrate what can be identified within inguinal hernias. Differentiating the types of herniated structures is of absolute importance for planning the appropriate treatment.

Keywords: Urinary bladder; Inguinal canal; Inguinal hernia; Testicular neoplasms; Metastasis; Ovary.

OBJECTIVE: To determine whether technetium-99m-labeled tropane derivative single-photon emission computed tomography (^99mTc-TRODAT-1 SPECT) provides results comparable to those of the less widely available, less accessible tool fluorine-18-labeled fluorodopa positron-emission tomography (¹⁸F-FDOPA PET) in the setting of a movement disorders clinic. MATERIALS AND METHODS: In this prospective pilot study, eight subjects with a clinical diagnosis of Parkinson’s disease were randomly selected from among patients under treatment at a movement disorders clinic and submitted to ^99mTc-TRODAT-1 SPECT and ¹⁸F-FDOPA PET. The results were read by two experienced observers, and a semiquantitative analysis was performed. RESULTS: The visual and semiquantitative analyses were concordant for all studies, showing that radiotracer uptake in the contralateral striatum on the most affected side was lower when ^99mTc-TRODAT-1 SPECT was employed. The semiquantitative analysis demonstrated a significant correlation between ¹⁸F-FDOPA PET and ^99mTc-TRODAT-1 SPECT (r = 0.73; p < 0.01). CONCLUSION: It appears that ^99mTc-TRODAT-1 SPECT is a valid option for the study of dopaminergic function in a clinical setting.

Keywords: Parkinson disease/diagnostic imaging; Parkinsonian disorders/diagnostic imaging; Tomography, emission-computed, single-photon/methods; Positron-emission tomography/methods; Tropanes/pharmacokinetics; Dihydroxyphenylalanine/analogs & derivatives.