[en] The recent explosion of ‘big data’ has ushered in a new era of artificial intelligence (AI) algorithms in every sphere of technological activity, including medicine, and in particular radiology. However, the recent success of AI in certain flagship applications has, to some extent, masked decades-long advances in computational technology development for medical image analysis. In this article, we provide an overview of the history of AI methods for radiological image analysis in order to provide a context for the latest developments. We review the functioning, strengths and limitations of more classical methods as well as of the more recent deep learning techniques. We discuss the unique characteristics of medical data and medical science that set medicine apart from other technological domains in order to highlight not only the potential of AI in radiology but also the very real and often overlooked constraints that may limit the applicability of certain AI methods. Finally, we provide a comprehensive perspective on the potential impact of AI on radiology and on how to evaluate it not only from a technical point of view but also from a clinical one, so that patients can ultimately benefit from it.

Key Points

• Artificial intelligence (AI) research in medical imaging has a long history

• The functioning, strengths and limitations of more classical AI methods is reviewed, together with that of more recent deep learning methods.

• A perspective is provided on the potential impact of AI on radiology and on its evaluation from both technical and clinical points of view.

[en] Although a rare disease, anal cancer is increasingly being diagnosed in patients with risk factors, mainly anal infection with the human papilloma virus. Magnetic resonance imaging (MRI) with external phased-array coils is recommended as the imaging modality of choice to grade anal cancers and to evaluate the response assessment after chemoradiotherapy, with a high contrast and good anatomic resolution of the anal canal. MRI provides a performance evaluation of size, extent and signal characteristics of the anal tumor before and after treatment, as well as lymph node involvement and extension to the adjacent organs. MRI is also particularly helpful in the assessment of complications after treatment, and in the diagnosis for relapse of the diseases

[en] The last few decades have witnessed tremendous technological developments in image-based biomarkers for tumor quantification and characterization. Initially limited to manual one- and two-dimensional size measurements, image biomarkers have evolved to harness developments not only in image acquisition technology but also in image processing and analysis algorithms. At the same time, clinical validation remains a major challenge for the vast majority of these novel techniques, and there is still a major gap between the latest technological developments and image biomarkers used in everyday clinical practice. Currently, the imaging biomarker field is attracting increasing attention not only because of the tremendous interest in cutting-edge therapeutic developments and personalized medicine but also because of the recent progress in the application of artificial intelligence (AI) algorithms to large-scale datasets. Thus, the goal of the present article is to review the current state of the art for image biomarkers and their use for characterization and predictive quantification of solid tumors. Beginning with an overview of validated imaging biomarkers in current clinical practice, we proceed to a review of AI-based methods for tumor characterization, such as radiomics-based approaches and deep learning.

Key Points

• Recent years have seen tremendous technological developments in image-based biomarkers for tumor quantification and characterization.

• Image-based biomarkers can be used on an ongoing basis, in a non-invasive (or mildly invasive) way, to monitor the development and progression of the disease or its response to therapy.

• We review the current state of the art for image biomarkers, as well as the recent developments in artificial intelligence (AI) algorithms for image processing and analysis.

[en] Magnetic resonance imaging is the optimal modality for pelvic imaging. It is based on T2-weighted magnetic resonance (MR) sequences allowing uterine and vaginal cavity assessment as well as rectal evaluation. Anatomical depiction of these structures may benefit from distension, and conditions either developing inside the lumen of cavities or coming from the outside may then be better delineated and localized. The need for distension, either rectal or vaginal, and the way to conduct it are matters of debate, depending on indication for which the MR examination is being conducted. In this review, we discuss advantages and potential drawbacks of this technique, based on literature and our experience, in the evaluation of various gynecological and rectal diseases

[en] To determine whether Hidradenitis suppurativa (HS)-related anoperineal disease can be distinguished from Crohn's disease (CD) using MRI. Pelvic MRI of 23 HS and 46 CD patients with anoperineal disease between 2007 and 2014 were independently analysed by two radiologists. For diagnosis of HS, sensitivity, specificity and positive likelihood ratios (LRs) of inflammatory features and of their anatomical distribution were calculated and compared to those of CD. In HS, fistulae were less present (P =.033) and less frequently involved the sphincters (P =.001) than in CD. Granulomas were more frequent (P =.0005). For anterior/inguinal and posterior localizations, sensitivity, specificity and LR for diagnosis of HS were 70% (49.1, 84.4), 87% (74.3, 93.9), 5.3 (2.41, 11.79) and 57% (36.8, 74.4), 93% (82.5, 97.8), 8.67 (2.74, 27.41), respectively. Combination of signs including posterior involvement, absence of rectal wall thickening and bilaterality of features yielded specificity of 100% (95% CI: 92.3-100) for HS. Although MRI presentations of anoperineal disease may overlap between CD and HS, specific diagnosis of HS is possible with a combination of three features: absence of features' predominance in perianal area, absence of rectal wall thickening and bilaterality of features. (orig.)

[en] 

Background

Severe spontaneous soft tissue hematomas (SSTH) are usually treated with transcatheter arterial embolization (TAE) although only limited retrospective studies exist evaluating this treatment option. The aim of this study was to systematically assess the efficacy and safety of TAE for the management of SSTH.

Methods

Medline, EMBASE, PubMed and Cochrane Library were searched from inception to July 2017 using MeSH headings and a combination of keywords. Eligibility was restricted to original studies with patients suffering from SSTH treated with TAE. Patients with traumatic hematomas or who were treated with solely conservative or surgical management were excluded. For each publication, clinical success based on the control of the bleed, rebleeding rates and complications (including mortality) was collected, as well as technical details.

Results

Sixty-three studies met the inclusion criteria, with an aggregate total of 267 patients. Follow-up extended from 1 day to 10 years. Bleeding was mainly localized to the iliopsoas (n = 113/267, 42.3%) and anterior abdominal wall (n = 145/266, 54.7%). When information was available, 81.0% (n = 158/195) of patients were on anticoagulant therapy prior to the bleeding episode. Initial stabilization with control of the bleed was obtained in 93.1% (n = 242 patients, n = 60 studies). The most common embolic materials were coils (n = 129, 54.4%). Rebleeding was reported in 25 patients (9.4%). Only two embolization complications were reported (0.7%). The 30-day mortality was 22.7% (n = 42/1857).

Conclusion

TAE represents a safe and effective procedure in the management of SSTH. We present a management algorithm based on these data, but further studies are needed to address the knowledge gap.

[en] To describe the magnetic resonance imaging (MRI) features of HIV-associated obliterative portopathy (HIV-OP) and determine the most indicative appearance of this condition on MRI by using a retrospective case-control study. MRI examinations of 24 patients with HIV-OP (16 men, 8 women; mean age = 48 ± 6.6 [SD] years; age range, 35–71 years) were analyzed by two blinded observers and compared with those obtained in 18 HIV-infected patients with hepatic cirrhosis (14 men, 4 women; mean age = 51 ± 3.4 [SD] years; age range, 35–60 years). Images were qualitatively and quantitatively analyzed with respect to imaging presentation. Comparisons were performed using uni- and multivariate analyses. Regular liver contours had the highest accuracy for the diagnosis of HIV-OP (83%, 35 of 42; 95% confidence interval [CI], 69–93%) and was the most discriminating independent variable for the diagnosis of HIV-OP (odds ratio, 51; 95%CI, 4.96–1272%) (p < 0.0001). At multivariate analysis, the width of segment 4 in millimeters (OR = 1.23 [95%CI, 1.05–1.44%]; p = 0.011) and the presence of regular liver contours (OR = 7.69 [95%CI, 1.48–39.92%]; p = 0.015) were the variables independently associated with the diagnosis of HIV-OP. Regular liver contours are the most discriminating independent variable for the diagnosis of HIV-OP but have limited accuracy. Familiarity with this finding may help differentiate HIV-OP from cirrhosis in HIV-infected patients.

[en] To test whether variations in apparent diffusion coefficient (ADC) values of uterine leiomyomas after uterine artery embolization (UAE) may correlate with outcome and assess the effects of UAE on leiomyomas and normal myometrium with magnetic resonance imaging (MRI). Data of 49 women who underwent pelvic MRI before and after UAE were retrospectively reviewed. Uterine and leiomyoma volumes, ADC values of leiomyomas, and normal myometrium were calculated before and after UAE. By comparison with baseline ADC values, a significant drop in leiomyoma ADC was found at 6-month post-UAE (1.096 x 10"-"3 mm"2/s vs. 0.712 x 10"-"3 mm"2/s, respectively; p < 0.0001), but not at 48-h post-UAE. Leiomyoma devascularization was complete in 40/49 women (82 %) at 48 h and in 37/49 women (76 %) at 6 months. Volume reduction and leiomyoma ADC values at 6 months correlated with the degree of devascularization. There was a significant drop in myometrium ADC after UAE. Perfusion defect of the myometrium was observed at 48 h in 14/49 women (28.5 %) in association with higher degrees of leiomyoma devascularization. Six months after UAE, drop in leiomyoma ADC values and volume reduction correlate with the degree of leiomyoma devascularization. UAE affects the myometrium as evidenced by a drop in ADC values and initial myometrial perfusion defect. (orig.)

[en] Esophageal peroral endoscopic myotomy (POEM) is the treatment of reference of major obstructive esophageal motility disorders but the detection of early complications remains challenging. Our aim was to report the radiological findings on meglumine diatrizoate esophagograms after esophageal POEM and identify variables associated with patient outcomes. The imaging and clinical files of 106 patients who underwent POEM for achalasia or other major obstructive esophageal motility disorders were retrospectively analyzed. Post POEM esophagograms were reviewed for the presence of pneumoperitoneum, pleural effusion, extraesophageal contrast leakage, and dislocated clips. Associations between length of hospital stay and radiological findings were searched for using a Cox multivariate analysis. A total of 106 patients (M/F = 56/50; mean age = 50 ± 2 [SD] years) underwent 106 POEM procedures with a meglumine diatrizoate esophagogram on postoperative day 1. Overall median hospital stay was 3 days (range 1–20 days). Pneumoperitoneum, pleural effusion, extraesophageal contrast leakage, and dislocated clips were observed in 90/106 (84.9%), 12/106 (11.3%), 4/106 (3.8%), and 0/106 (0%) patients, respectively. At multivariate analysis, pleural effusion (p = 0.005; adjusted hazard ratio [aHR] = 0.35 [95% CI 0.17–0.73]) and extraesophageal contrast leakage (p = 0.039; aHR = 0.27 [95% CI 0.08–0.94]) were associated with a prolonged hospital stay. Pneumoperitoneum was not associated with unfavorable outcome (p = 0.99). Pneumoperitoneum is a common finding after POEM and is not indicative of unfavorable patient outcome. Conversely, post POEM pleural effusion and extraesophageal contrast leakage are associated with a longer hospital stay.

[en] Postpartum hemorrhage (PPH) is a potentially life-threatening condition, which needs multidisciplinary management. Uterine atony represents up to 80 % of all causes of PPH. Transcatheter arterial embolization (TAE) has now a well-established role in the management of severe PPH. TAE allows stopping the bleeding in 90 % of women with severe PHH, obviating surgery. Pledgets of gelatin sponge as torpedoes are commonly used for safe TAE, and coils, glue, and microspheres have been primarily used in specific situations such as arterial rupture, pseudoaneurysm, and arteriovenous fistula. TAE is a minimally invasive procedure with a low rate of complications, which preserves future fertility. Knowledge of causes of PPH, potential risks, and limitations of TAE is essential for a timely decision, optimizing TAE, preventing irreversible complications, avoiding hysterectomy, and ultimately preserving fertility