Artificial Intelligence in Interventional Radiology: A Literature Review and Future Perspectives.

The term "artificial intelligence" (AI) includes computational algorithms that can perform tasks considered typical of human intelligence, with partial to complete autonomy, to produce new beneficial outputs from specific inputs. The development of AI is largely based on the introduction of artificial neural networks (ANN) that allowed the introduction of the concepts of "computational learning models," machine learning (ML) and deep learning (DL). AI applications appear promising for radiology scenarios potentially improving lesion detection, segmentation, and interpretation with a recent application also for interventional radiology (IR) practice, including the ability of AI to offer prognostic information to both patients and physicians about interventional oncology procedures. This article integrates evidence-reported literature and experience-based perceptions to assist not only residents and fellows who are training in interventional radiology but also practicing colleagues who are approaching to locoregional mini-invasive treatments.

Reliability and accuracy of scout CT in the detection of vertebral fractures.

OBJECTIVE: The aim of the present study was to evaluate the reliability of scout CT (sCT) lateral radiograph, in terms of diagnostic accuracy and intra- and interobserver agreement in the detection of vertebral fractures (VFs). METHODS: 300 CT examinations of the thoracic and/or lumbar spine were collected and independently analysed by 3 musculoskeletal radiologists in 2 different sessions. A semi-quantitative approach was used for VF assessment on sCT, and morphometric analysis was performed when a VF was suspected. Results of multiplanar sagittal CT reconstructions interpreted by the most expert radiologist were considered as gold standard. Arthrosis was also scored. Only vertebral bodies assessable by both sCT and gold standard were considered for the analysis. Area under the receiver operating characteristic curve (AUROC), Cohen's kappa statistic and linear-by-linear association were used for statistical analysis. RESULTS: 1522 vertebrae were considered (130 males and 170 females; ages, 73.0±2.8 years). 73 of 1522 (4.8%) VFs were identified in 34/300 patients (11.3%). In the detection of VFs, the sensitivity and specificity of sCT were 98.7% and 99.7%, respectively. Accuracy (AUROC=0.992±0.008), as well as interobserver agreement (k=0.968±0.008), was excellent. Intra-observer agreement was perfect (k=1.000). Performance of this method was independent of arthrosis, vertebral level and type and grade of VFs. CONCLUSION: sCT is a simple but very accurate method for the detection of VFs. It should be introduced as a spine evaluation tool for the detection of VFs in examinations that are performed for other diagnostic purposes. ADVANCES IN KNOWLEDGE: sCT lateral radiograph is an accurate tool for the detection of VFs. This technique may be used with several advantages in clinical practice.

Integrated software suite for magnetocardiographic data analysis--a proposal based on an interactive programming environment.

OBJECTIVES: This paper describes an integrated software suite (ISS) for the processing of magnetocardiographic (MCG) recordings obtained with super-conducting multi-channel systems having different characteristics. We aimed to develop a highly flexible suite including toolboxes for current MCG applications, organized consistently with an open architecture that allows function integrations and upgrades with minimal modifications; the suite was designed for the compliance not only of physicists and engineers but also of physicians, who have a different professional profile and are accustomed to retrieve information in different ways. METHODS: The MCG-ISS was designed to work with all common graphical user interface operative systems. MATLAB was chosen as the interactive programming environment (IPE), and the software was developed to achieve usability, interactivity, reliability, modularity, expansibility, interoperability, adaptability and graphics style tailoring. Three users, already experienced in MCG data analysis, have intensively tested MCG-ISS for six months. A great amount of MCG data on normal subjects and patients was used to assess software performances in terms of user compliance and confidence and total analysis time. RESULTS: The proposed suite is an all-in-one analysis tool that succeeded in speeding MCG data analysis up to about 55% with respect to standard reference routines; it consequently enhanced analysis performance and user compliance. CONCLUSIONS: Those results, together with the MCG-ISS advantage of being independent on the acquisition system, suggest that software suites like the proposed one could uphold a wider diffusion of MCG as a diagnostic tool in the clinical setting.

Total body MR angiography and atherosclerosis.

The early detection of atherosclerotic vascular lesions is very important for diagnostic and interventional purposes. Traditionally, Digital Subtraction Angiography (DSA) is considered the reference diagnostic technique, but recently several new non-invasive procedures have been developed, like Doppler US, CT-angiography and MR-Angiography (MRA). MRA has progressively gained acceptance as a valid alternative. At present, the use of fast sequence and contrast injection allows to acquire segmental volumes within a few seconds (10-20s), with high diagnostic quality and accuracy. The systemic distribution of atherosclerosis requires the use of techniques which can assess the arterial system as exhaustively as possible. A MRA scanning protocol including all arteries from the epiaortic branches to the calf has recently been proposed with encouraging preliminary results. In this article, the relevant technical concepts in MRA and the present most important clinical findings are reported and discussed, including the proposed technique for a whole-body MR angiographic assessment of the atherosclerotic patient.

Malignant pleural disease.

The vast majority of pleural neoplasms invade the pleura secondarily and can be seen in patients with bronchogenic carcinoma, breast cancer, lymphoma, and ovarian or gastric carcinoma. Primary pleural neoplasms are less common, although they have developed notoriety since the up-surge of malignant mesothelioma and the knowledge of its connection to asbestos exposure. Other malignant primary tumors include localized fibrous tumor and pleural liposarcoma. In most patients with diffuse malignant pleural disease the chest radiograph shows pleural effusion with or without pleural thickening. Computed tomography (CT) usually provides precise localization and extent of the disease and may be of value in assessing chest wall and mediastinal involvement. In specific situations, magnetic resonance (MR) may be useful as a problem-solving tool when CT findings of chest wall or diaphragmatic invasion are equivocal or in patients with contraindication to intravenous administration of ionic contrast material.

[Magnetic resonance angiography of the peripheral vessels with automatic moving bed infusion tracking]. / Angiografia con Risonanza Magnetica del circolo periferico con spostamento automatico del tavolo portapaziente.

PURPOSE: To investigate the actual diagnostic reliability of the Mobitrack technique with a slow intravenous infusion of paramagnetic contrast agent (CA) in MR Angiography of the peripheral arterial district. MATERIAL AND METHODS: Twelve healthy volunteers (mean age: 34) with no personal or family history of peripheral arterial pathologic conditions, underwent MR Angiography of the peripheral vascular district. A 1.5 T superconductive magnet equipped with automatic table feed was used. In the preliminary phase, the circulation time at the abdominal aorta was optimized and customized for each patient. This was done by performing a pre-targeting Fast Field Echo 2D (FFE 2D) sequence with intravenous administration of 1-2 mL CA by an injector, to evaluate the delay time. A 2D Time of Flight (2D TOF) sequence was then performed for topographic purposes. The partially overlapping volumes were acquired using Fast T1-weighted sequences, intravenous CA administration and an automatic table feed of 10 mm/s. A Fast Field Echo 3D (FFE 3D) T1-weighted sequence with TR/TE/FA: of 6.3/1.6/40 degrees and a slice thickness of 1.5 mm were also performed. Thirty to forty mL CA were slowly administered intravenously at a rate of 0.3-0.6 mL/s. Two blinded readers independently evaluated the images giving one of three diagnostic judgements: 1) arteries were well visualized, 2) heterogeneous arteries with(out) the presence of veins, and 3) arteries seen poorly or not at all. The first two judgements were considered diagnostic. The readers considered 19 different anatomical districts for each patient, giving a total of 190 evaluations. RESULTS: A blinded evaluation of the readers judgements did not indicate a statistically significant difference (agreement: 100%). Overall, 82% of the images were rated as 1, 8.5% as 2 and 8.4% as 3. DISCUSSION: In 174/190 judgements the vessels were rated as 1 or 2, that is of diagnostic value. Judgement 3 was always due to the inability to visualize the medial and/or distal third of the arterial circulation of the leg. CONCLUSIONS: The results of this technique optimization study confirm the overall validity of the Mobitrack technique. However they also indicate that further technical advances are required to ensure maximum diagnostic accuracy in this vascular district.

[Optimization and diagnostic accuracy of computerized tomography with tridimensional spiral technique in the study of craniostenosis]. / Ottimizzazione e accuratezza diagnostica della Tomografia Computerizzata con tecnica spirale tridimensionale nello studio della craniostenosi.

INTRODUCTION: Conventional Computed Tomography (CT) with three-dimensional (3D) reconstructions is considered the most complete and accurate imaging modality to diagnose craniosynostosis. However, the introduction of Spiral CT (SCT) opened new possibilities for 3D studies of the skull in pediatric patients with craniosynostosis. The purpose of our study is two fold: first, to optimize the scanning and imaging parameters to obtain diagnostic images in a single spiral scan; second, to assess the diagnostic accuracy of such images in the identification of normal and abnormal cranial vault sutures. MATERIAL AND METHODS: Seventy-eight pediatric patients (age range: 1-35 months; mean: 11.8 months) with craniosynostosis were submitted to SCT of the head. The images were acquired with the following parameters: 3- and 5-mm nominal slice thickness, 5-6 mm/s table feed (pitch 1-2), 165 mAs and 120 kV. Two different algorithms and increases were used for image reconstructions. A first set of images was reconstructed with 2-mm increases and a soft tissue algorithm: these images were used for brain studies and for 3D reconstructions. A second set of slices was reconstructed with 5-mm increases and a bone algorithm to visualize the sutures of the axial plane. The 3D images were processed with the Shaded Surface Display software with threshold values ranging 120-150 HU. All images were acquired with a single spiral scan lasting less than 30 seconds. Two blinded radiologists analyzed the 3D and the planar images independently to evaluate the course and depth of each cranial suture. The sensitivity, specificity and diagnostic accuracy of both 3D and planar SCT images were evaluated. The frequency of artifacts (the Lego effect, boiled egg, pseudoforamina, movement, and chainsaw artifacts) and their influence on the final diagnosis were studied on 3D SCT images. RESULTS: The diagnostic accuracy rates of 3D SCT images, by suture, were: sagittal 90.7%, metopic 100%, left lamboid 90.9%, right lamboid 93.9%, left coronal 85.7%, right coronal 91.1%. The diagnostic accuracy rates of the axial images, by suture, were: sagittal 90.7%, metopic 95.5%, left lamboid 86.4%, right lamboid 90.9%, left coronal 83.7%, right coronal 91.1%. The interobserver agreement on 3D images was: sagittal 91.1%, metopic 100%, left lamboid 88.9%, right lamboid 91.1%, left coronal 88.9%, right coronal 84.4%. The Lego effect artifact was the most frequent one (82%) and affected image evaluation in 6.3% of cases. CONCLUSIONS: Our results prove that 3D SCT is a very accurate technique for identifying normal and abnormal sutures and presents many advantages over conventional 3D CT in the examination of pediatric patients with craniosynostosis. The quality of 3D SCT images was adequate and the artifacts did not affect the final diagnostic yield significantly.

Bronchioloalveolar carcinoma of the lung.

Bronchioloalveolar carcinoma is a histologically distinct form of pulmonary adenocarcinoma representing an estimated 2-10 % of all primary lung cancers. Its varied appearances include focal masses, nodular patterns, and pneumonic and diffuse forms so that bronchioloalveolar carcinoma should be considered in the differential diagnosis of solitary or multiple pulmonary nodules and acute or chronic alveolar diseases. In this article we describe the different radiographic manifestations of bronchioloalveolar carcinoma with particular emphasis on CT findings and those signs that may help in identifying the lesion as bronchioloalveolar carcinoma.

Neoplastic extension across pulmonary fissures: value of spiral computed tomography and multiplanar reformations.

To assess the value of spiral computed tomography (CT) with multiplanar reformations for detection of neoplastic extension across pulmonary fissures, 51 patients with a lung neoplasm near a fissure underwent spiral CT, followed by multiplanar reformations, and spaced thin-section CT scans through the area of contact between tumor and fissure. The CT studies were evaluated for visibility of fissures and their relationship to the tumor. Imaging findings were compared with surgical results in 31 patients who underwent thoracotomy. Visibility of fissures on multiplanar reformations was either good or acceptable in 47 (92.2%) patients, and poor in four. Surgical findings of neoplastic extension across the major or the minor fissure were present in seven and eight patients, respectively. Thin-section CT scans were 83.3% sensitive in assessing neoplastic involvement of the major fissure, axial CT scans were 57.1% sensitive, and spiral CT multiplanar images were 100% sensitive. In the evaluation of the minor fissure, thin-section CT and axial spiral CT scans were considered inconclusive in six patients whereas multiplanar reformations enabled correct assessment of the fissure/neoplasm relationship in all but one patient. Spiral CT multiplanar images are accurate for detection of transfissural neoplastic extension, and are superior to axial CT scans for evaluation of tumors near the minor fissure.

Staging of thoracic lymphoma by radiological imaging.

Thoracic lymphomas, which are very common especially in Hodgkin's disease patients, are characterised by enlargement of mediastinal lymph nodes, parenchymal abnormalities, and pleural, pericardial and chest wall involvement. The use of several imaging techniques has been proposed in order to assess the extent of the disease correctly and to plan therapy. The most relevant results in this field, especially those using computed tomography (CT), magnetic resonance imaging (MRI) and gallium scanning, are summarised in this review. Presently CT is widely and successfully used in staging patients, whereas MRI seems to be preferable, as a second-step technique, if pericardial, pleural and chest wall involvement are suspected. The role of gallium scanning is limited in the staging, although it could be relevant in the follow-up of treated patients.

Magnetic resonance angiography and colour-Doppler sonography in the evaluation of abdominal aortic aneurysms.

This prospective study was aimed at comparing the diagnostic accuracy of magnetic resonance angiography (MRA) with colour-Doppler ultrasonography (colour-Doppler US) in the assessment of abdominal aortic aneurysms (AAA). Twenty patients with abdominal aortic aneurysms underwent MRA, colour-Doppler US, digital subtraction angiography (DSA) and CT. The MRA technique and colour-Doppler findings were compared with DSA as well as surgical and pathological findings, which were considered as the gold standard. In 6 patients who refused surgery, CT and DSA were considered as the gold standard. The MRA technique always correctly assessed the size and site of the aneurysms, the involvement of the renal and common iliac arteries, the course of the left renal vein, the thrombotic component and the calcifications. Colour-Doppler US always correctly assessed the size and site of the aneurysms, the thrombotic component and calcifications and the involvement of the iliac arteries. Our preliminary results suggest that MRA together with colour-Doppler US represents a valid alternative to invasive imaging in the assessment of AAA.

[Malignant pulmonary neoplasms: diagnostic possibilities of magnetic resonance angiography]. / Neoplasie maligne polmonari: possibilità diagnostiche dell'angiografia con Risonanza Magnetica.

The authors investigated the potentials of Magnetic Resonance Angiography (MRA) in the preoperative staging of malignant central lung neoplasms. Fifteen patients with malignant central lung neoplasms were submitted to MRA 48 hours before surgery, which was the gold standard. The patients were 7 women and 8 men; their mean age was 54.3 years (range: 39-65 years). MRA was performed with the 2D and 3D time-of-flight (TOF) technique. FLASH 2D sequences (FA 18 degrees, TR 40 ms, TE 10 ms, SL 4 mm) and FISP 3D sequences (FA 20 degrees, TR 30 ms, TE 3 ms, SL 1 mm) were used. The images were processed with the maximum intensity projection (MIP) and rotated on different planes with a 15 degrees step. A multiple choice card, implying preoperative reading by an MRA expert, was used; in the study of the relationship between neoplasms and contiguous vessels, only two diagnoses were possible--i.e., infiltrated, not infiltrated. This card included, in the preliminary phase, a code for each MRA pattern--i.e., the presence of a clear cleavage plane, vascular occlusion, stenosis, irregular vessel profile, turbulence and several of these patterns together. MRA was in agreement with surgery in 14/16 cases and overestimated two cases as infiltration. In our preliminary study, MRA had 100% sensitivity, 75% specificity and 87.5% diagnostic accuracy. To conclude, MRA proved to be a complementary tool to spin-echo MR sequences in the staging of malignant central lung neoplasms.

Pulmonary embolism: the role of computed tomography and magnetic resonance imaging.

The technological progress in Computed Tomography (CT) (spiral and electron beam) and Magnetic Resonance Imaging (MRI fast sequences) has stimulated their interest in the diagnosis of acute and chronic pulmonary embolism (PE). They are noninvasive procedures able to identify thrombi up to the level of segmental pulmonary branches. This result, albeit not ideal, is significant, in view of the lower clinical relevance of peripheral emboli as compared to more central locations, especially in the absence of peripheral venous thrombosis. Spiral CT allows satisfactory assessment of pulmonary branches with high sensitivity (65-100%), specificity (89-96%), positive predictive value (95%) and negative predictive value (80-100%) in the diagnosis of PE. MRI with spin-echo sequences has also a satisfactory sensitivity (75-90%), specificity (up to 100%), positive predictive value (86%) and negative predictive value (85%). Recently, MR angiography was shown to be able to depict smaller pulmonary branches (6th and 7th generation), even if its efficacy in the identification of emboli has not been demonstrated as yet. CT and MRI are bound to play an increasingly relevant role in the diagnosis of PE.

[Spiral computerized tomography and videothoracoscopy in the assessment of contralateral nodular lesions in patients with bronchogenic carcinoma]. / La Tomografia Computerizzata spirale e la videotoracoscopia nella valutazione di lesioni nodulari controlaterali nei pazienti con carcinoma broncogeno.

Recent improvements in endoscopic technology and surgical techniques have widened the application field of video-assisted thoracoscopy (VAT). We report our personal experience in 14 male patients (mean age: 67 years, range: 55-73 years) in whom one or multiple indeterminate contralateral lung nodules were found during bronchogenic carcinoma staging and then surgically resected with VAT. All patients underwent volumetric CT of the chest. Sixteen lung nodules were detected contralateral to the neoplasm; their mean diameter was 5 mm (range: 2-10 mm). The mean distance between pleural surface and lung nodule was 8 mm. All patients had primary lung cancer (3 central and 11 peripheral lesions), histologically confirmed by bronchoscopic or percutaneous CT-guided biopsy. None of them had any contraindication to surgery because of extrathoracic pathologic conditions. VAT was performed as normal, under general anesthesia, with assisted ventilation with a double-lumen endotracheal tube and using a percutaneous mechanical stapler. The nodules were easier to identify using a skin reference point corresponding to the parietal projection of the nodule, positioned with CT before surgery. Surgery lasted 58 minutes on the average (range: 30-120 minutes). In all patients VAT was successful in resecting the nodule. In 9 patients a metastasis from a contralateral lung cancer was found: 4 adenocarcinomas, 4 epidermoid carcinomas and 1 small cell carcinoma. In the remaining 5 patients, VAT-resected lung nodules were of chronic inflammatory nature. The latter patients underwent definitive surgery of the primary tumor (2 adenocarcinomas, 2 epidermoid and 1 large cell carcinomas) ten days later (range: 9-30 days). There were no major complications but a prolonged air leak in one patient, which needed drainage to be maintained for 5 days. Presently, VAT permits an atypical resection, avoiding the morbility of thoracoscopy and thus represents a mandatory technique in selected patients amenable to definitive surgery.

Coronary arteries and athlete's heart.

An increase of coronary artery size after endurance training has been suggested by experimental data on animals and anecdotal autopsy reports in men. However, systematic studies on in vivo coronary anatomy of athletes have been lacking so far. We utilized two-dimensional echocardiography (2DE) to explore non-invasively the coronary anatomy of endurance athletes. Twenty long-distance runners (LDR) and 20 matched sedentary controls (SC) were studied initially. Visualization of the ostia and main trunks of-right (RCA) and left coronary artery (LCA) was obtained in 90-100 p. 100 of LDR and 70-75 p, 100 of SC. Collateral branches of LCA (anterior descending artery and circumflex branch) and RCA were visualized respectively in 60-70 p. 100 and 30-40 p, 100 of cases. The very good quality of images made possible the measurement of LCA and RCA size. LDR as a group had significantly larger coronary arteries than SC: this was associated with significant left and right ventricular enlargement and hypertrophy. These results have been further confirmed in a large survey of triathletes, swimmers, water-polo players, young LDR and prepubescent football players. Increase of coronary artery size is a well-documented effect of endurance training which can be easily investigated with 2DE, However, the large interindividual variability and the observation of very large coronary arteries in adolescent subjects suggest that genetic factors may also play a role in determining the final size of the coronary vessels.

Gastric wall thickness in normal and neoplastic subjects: a prospective study performed by abdominal ultrasound.

Gastric wall thickness (body-antrum) was blind measured prospectively by real-time ultrasound in 58 patients (30 with gastric cancer and 28 healthy) who had previously undergone endoscopy. Gastric wall thickness on the average measured 15.933 +/- 4.471 mm in the neoplastic patients and 5.107 +/- 1.100 mm in the normal subjects. Seven millimeters was the highest value found in the normal subjects (4 cases) and the minimum value found in the neoplastic patients (1 case). Knowing the normal gastric wall thickness value on a standard ultrasound examination of the upper abdomen is useful, as ultrasound is often performed as a screening or first-step procedure, in order to address the patients with higher values toward more specific techniques.