Artificial intelligence and machine learning in cancer imaging.

An increasing array of tools is being developed using artificial intelligence (AI) and machine learning (ML) for cancer imaging. The development of an optimal tool requires multidisciplinary engagement to ensure that the appropriate use case is met, as well as to undertake robust development and testing prior to its adoption into healthcare systems. This multidisciplinary review highlights key developments in the field. We discuss the challenges and opportunities of AI and ML in cancer imaging; considerations for the development of algorithms into tools that can be widely used and disseminated; and the development of the ecosystem needed to promote growth of AI and ML in cancer imaging.

Implementation of a computed tomography dose management program across a multinational healthcare organization.

OBJECTIVES: Radiation dose index monitoring (RDIM) systems may help identify CT dose reduction opportunities, but variability and complexity of imaging procedures make consistent dose optimization and standardization a challenge. This study aimed to investigate the feasibility to standardize and optimize CT protocols through the implementation of a Dose Excellence Program within a European healthcare network. METHODS: The Dose Excellence Program consisted of a multidisciplinary team that developed standardized organizational adult CT protocols and thresholds for relevant radiation dose indices (RDIs). Baseline data were collected retrospectively from the RDIM (Phase I, 2015). Organization's protocols were implemented and monitored from the RDIM for deviations (Phase II, 2016). Following standardization, radiation dose optimization was initiated (Phase III, 2017). Data from the three most used protocols were retrospectively extracted and grouped by country for all phases. The mean number of series (RS) and RDIs were compared between phases and with organizational reference levels. A Mann-Whitney test was conducted; p < .05 was considered as significant. RESULTS: Data from 9588, 12638, and 6093 examinations were analyzed from General Chest, General Head, and Thorax/Abdomen/Pelvis (TAP) multiphase respectively. Overall, after Phase III, mean RS and CTDIvol p75 were below the organizational reference levels in all countries for the three protocols. The CTDIvol decreased by 45% in Switzerland (p < .00001), 32% in Turkey (p < .00001), and 28% in Switzerland (p = .0027) for General Chest, General Head, and TAP multiphase respectively. CONCLUSIONS: The implementation of a Dose Excellence Program within a large-scale healthcare organization allowed unifying protocols and optimizing radiation dose across countries. KEY POINTS: • Engaging a multidisciplinary team can enhance the use of an RDIM system for CT dose management in a multinational healthcare environment. • Deep dive of baseline data and standardization of CT practices by defining organizational clinical indication CT protocols with RPIDs is an essential step before optimization of radiation dose. • Following the implementation of the program, the mean RS and CTDIvol were below or equal to the organizational reference levels in all countries.

Artificial intelligence for reduced dose 18F-FDG PET examinations: a real-world deployment through a standardized framework and business case assessment.

BACKGROUND: To determine whether artificial intelligence (AI) processed PET/CT images of reduced by one-third of 18-F-FDG activity compared to the standard injected dose, were non-inferior to native scans and if so to assess the potential impact of commercialization. MATERIALS AND METHODS: SubtlePET™ AI was introduced in a PET/CT center in Italy. Eligible patients referred for 18F-FDG PET/CT were prospectively enrolled. Administered 18F-FDG was reduced to two-thirds of standard dose. Patients underwent one low-dose CT and two sequential PET scans; "PET-processed" with reduced dose and standard acquisition time, and "PET-native" with an elapsed time to simulate standard acquisition time and dose. PET-processed images were reconstructed using SubtlePET™. PET-native images were defined as the standard of reference. The datasets were anonymized and independently evaluated in random order by four blinded readers. The evaluation included subjective image quality (IQ) assessment, lesion detectability, and assessment of business benefits. RESULTS: From February to April 2020, 61 patients were prospectively enrolled. Subjective IQ was not significantly different between datasets (4.62±0.23, p=0.237) for all scanner models, with "almost perfect" inter-reader agreement. There was no significant difference between datasets in lesions' detectability, target lesion mean SUVmax value, and liver mean SUVmean value (182.75/181.75 [SD:0.71], 9.8/11.4 [SD:1.13], 2.1/1.9 [SD:0.14] respectively). No false-positive lesions were reported in PET-processed examinations. Agreed SubtlePET™ price per examination was 15-20% of FDG savings. CONCLUSION: This is the first real-world study to demonstrate the non-inferiority of AI processed 18F-FDG PET/CT examinations obtained with 66% standard dose and a methodology to define the AI solution price.

Lead exposure in clinical imaging - The elephant in the room.

PURPOSE: Radiation Protection Apparel (RPA) is used during diagnostic imaging and interventional procedures to minimise incidental radiation exposure. The majority of RPA in use are lead-containing, which has until now been considered safe. A recent single-centre study has demonstrated that the external surface of 63 % of RPA was contaminated with lead dust. The purpose of this study was to reproduce this investigation with a larger sample size across Europe and assess whether decontamination procedures were possible. METHOD: The routine RPA Quality Control (QC) process was adapted to include lead dust contamination tests and decontamination if present. The presence of lead dust was determined using a commercially available colorimetric method. RPA that failed initial QC or could not be decontaminated were removed from use. RESULTS: From June to October 2019, 728 RPA from 85 imaging centres from five countries underwent initial QC. Of these, 712 were tested for lead dust contamination which was present on 162 (23 %). Following cleaning, 85 (12 %) remained contaminated and were removed from use. Linear regression analysis shows a significant correlation between type of RPA and contamination, (p = 0.0015). There was no correlation between contamination and imaging department, year of manufacture, country and RPA condition (p-values 0.98, 0.90, 0.94 and 0.14 respectively). CONCLUSIONS: Lead dust contamination is present on 23 % of RPA that would pass routine QC procedures. Approximately half were not amenable to decontamination and were removed from use. Procedures were introduced for the routine handling of RPA, and updated QC steps for assessment and cleaning. Lead-free RPA should be considered.

Role of Smoking in the Evolution of Cardiovascular Magnetic Resonance and Laboratory Findings of Acute Myocarditis.

PURPOSE: The purpose is to investigate cardiac magnetic resonance and laboratory findings in patients with clinically suspected acute myocarditis and re-assess the evolution of findings in relation to clinical parameters and smoking habits. METHODS: We prospectively analyzed 68 consecutive patients (4 females, 64 males, median age 25 years) at baseline and 51 patients 12 months later with regard to age, symptoms, and signs, smoking history, cardiac troponin I, erythrocyte sedimentation rate, c-reactive protein blood levels, electrocardiography changes, and cardiac magnetic resonance findings. Statistical analysis included group comparisons and linear regression between clinical parameters and the obtained data. RESULTS: A statistically significant correlation was recorded between smoking and late gadolinium enhancement extent, both at baseline and follow-up study. Late gadolinium enhancement extent was positively associated with cardiac troponin I serum levels and c-reactive protein and negatively with left ventricular ejection fraction at baseline study. Myocardial segments 4 and 5 were most frequently involved. Late gadolinium enhancement persisted in 96% of patients with no significant extent change at 12-month follow-up, while improved. CONCLUSIONS: A strong correlation was recorded between smoking patients with acute myocarditis and extent both at baseline and follow-up cardiac magnetic resonance. Myocardial segments 4 and 5 involvement was most prevalent. Late gadolinium enhancement persisted at follow-up, its incidence was higher than that reported in other studies and did not have an impact on the patient's clinical status or cardiac function. However, longer-term follow-up is highly recommended in these patients.

Perivascular extension of microwave ablation zone: demonstrated using an ex vivo porcine perfusion liver model.

Microwave ablation (MWA) has been proposed to suffer less from the heat sink effect compared to radiofrequency ablation but has been reported to cause extension of the ablation zone along intrahepatic vessels in clinical practice. To study this effect in detail, eight fresh porcine livers were perfused in an ex vivo organ perfusion system. Livers were perfused with oxygenated, O-positive human blood at 37 °C. Perfusion was discontinued immediately before ablation in the non-perfused group (n = 4) whilst in the perfused group (n = 4) perfusion was maintained during MWA (140 W X 2 min). Large intrahepatic vessels (> 6 mm) were avoided using ultrasound. MWA zones were bisected within 30 min of perfusion termination and sections were fixed in formalin and stained with H&E and NADH to assess cell viability. Magnetic resonance imaging (MRI) was performed on two livers (one perfused, one non-perfused) to provide imaging correlation before sectioning. Twenty-one out of a total of 30 MW ablation zones (70%) showed extension of the ablation zone along a vessel. There was no statistically significant difference (p = 1) in the incidence of ablation zone extension between perfused (9/13, 69%) and non-perfused organs (12/17, 71%). MRI also demonstrated ablation zone extension along blood vessels correlating with macroscopy in two livers. NADH staining also confirmed extension of the ablation zone. Liver MWA appears to be commonly associated with propagated thermal injury along adjacent vessels and occurs independent of active blood flow. In order to avoid possible complications through non-target tissue injury, this effect requires further investigation.

Cross-sectional study of the provision of interventional oncology services in the UK.

OBJECTIVE: To map out the current provision of interventional oncology (IO) services in the UK. DESIGN: Cross-sectional multicentre study. SETTING: All National Health Service (NHS) trusts in England and Scottish, Welsh and Northern Ireland health boards. PARTICIPANTS: Interventional radiology (IR) departments in all NHS trusts/health boards in the UK. RESULTS: A total of 179 NHS trusts/health boards were contacted. We received a 100% response rate. Only 19 (11%) institutions had an IO lead. 144 trusts (80%) provided IO services or had a formal pathway of referral in place for patients to a recipient trust. 21 trusts (12%) had plans to provide an IO service or formal referral pathway in the next 12 months only. 14 trusts (8%) did not have a pathway of referral and no plans to implement one. 70 trusts (39%) offered supportive and disease-modifying procedures. One trust had a formal referral pathway for supportive procedures. 73 trusts (41%) provided only supportive procedures (diagnostic or therapeutic). Of these, 43 (59%) had a referral pathway for disease-modifying IO procedures, either from a regional cancer network or through IR networks and 30 trusts (41%) did not have a referral pathway for disease-modifying procedures. CONCLUSION: The provision of IO services in the UK is promising; however, collaborative networks are necessary to ensure disease-modifying IO procedures are made accessible to all patients and to facilitate larger registry data for research with commissioning of new services.

Effect of Hepatic Perfusion on Microwave Ablation Zones in an Ex Vivo Porcine Liver Model.

PURPOSE: To compare the size of ablation zones derived from nonperfused ex vivo livers with ablation zones created using an ex vivo perfused porcine liver model. MATERIALS AND METHODS: Six fresh porcine livers were used to evaluate microwave ablation (MWA). Perfused (n = 3) and nonperfused (n = 3) livers were warmed to 37°C by oxygenated, O-positive human blood reconstituted with Ringer solution, using an organ perfusion circuit. During MWA, perfusion was discontinued in the nonperfused group and maintained in the perfused group. After MWA (140 watts × 2 min at 2.45 GHz) with the Acculis MTA System (AngioDynamics, Latham, New York), ablation zones were bisected sagittally. Sections were stained with nicotinamide adenine dinucleotide (NADH) and hematoxylin-eosin to assess viability of cells in ablation and marginal zones. RESULTS: Comparison of 22 MWA zones (9 in perfused group, 13 in nonperfused group) was performed. Ablation zones demonstrated a central "white" and peripheral "red" zone. Cells in the white zone were nonviable with no NADH staining. The red zone showed progressive NADH staining toward the periphery, suggesting incomplete cell death. White and red zones of the perfused group were significantly smaller compared with the nonperfused group (short axis, 17.8 mm ± 2.7 vs 21.1 mm ± 3.2, P = .003; long axis, 40.69 mm ± 3.9 vs 39.63 mm ± 5.2, P = .44; intermediate zone,1.33 mm ± 0.04 vs 2.7 mm ± 0.14, P < .0001; mean ± SD). CONCLUSIONS: MWA algorithms provided by this manufacturer are based on nonperfused organ data, which overestimate ablation zone size. Data from perfused liver models may be required for more accurate dosimetry guidelines.

Aspergillosis complicating a microwave ablation cavity.

We present a case of a patient who following chemotherapy developed semi-invasive pulmonary aspergillosis and an aspergilloma in a lung cavity previously formed by microwave ablation (MWA). A 55-year-old woman presented with cough and shortness of breath after finishing three cycles of chemotherapy for a metastatic nerve sheath tumour. She had been treated by MWA for pulmonary metastases 2 years previously which resulted in a residual right apical lung cavity. Postchemotherapy imaging showed that this cavity had enlarged, developed a thicker wall and contained lobulated soft tissue with a crescent sign on coronal reformats. In addition, the patient's Aspergillus-specific IgG was markedly raised. Treatment with itraconazole improved the symptoms and reduced the cavity size and wall thickness. This case shows that persisting lung cavities after MWA are a potential site for semi-invasive aspergillosis and has implications for the timing of chemotherapy in patient with metastatic lung disease.

Perivascular parenchymal extension of the ablation zone following liver microwave ablation.

A 69-year-old man who presented with abdominal discomfort was, on examination, found to have a palpable abdominal mass. Contrast-enhanced CT showed a mass arising from the inferior vena cava, which biopsy confirmed to be a leiomyosarcoma. One month after chemoradiotherapy, CT demonstrated a new 15 mm solitary central right liver metastasis. Microwave ablation (MWA) of the metastasis was performed using an Acculis Sulis V system (Angiodynamics, USA) at a power of 140 Watts for 4 min, with no immediate complications. After 1 month, MRI with gadolinium was performed to assess the liver ablation zone. The MRI demonstrated thrombosis of a right inferior hepatic vein branch leading to the ablation zone and extension of the ablation zone 1 cm into the tissue around the thrombosed vessel.

Percutaneous High-Energy Microwave Ablation for the Treatment of Pulmonary Tumors: A Retrospective Single-Center Experience.

PURPOSE: To evaluate the safety and efficacy of percutaneous high-energy microwave ablation (MWA) for the treatment for pulmonary tumors. MATERIALS AND METHODS: A retrospective review was undertaken of 44 patients (21 men, 23 women; median age, 66 y; range, 17-89 y) who underwent 62 sessions of high-energy MWA for 87 pulmonary tumors at a single tertiary referral center between June 2012 and June 2014. Primary tumor origin was sarcoma (n = 23), colorectal (n = 16), lung (n = 2), esophageal (n = 1), breast (n = 1), and bladder (n = 1). Median tumor size was 12 mm (range, 6-45 mm). Technical success was recorded contemporaneously, complication rate at 30 days was recorded prospectively, and technique effectiveness was assessed by longitudinal follow-up CT scan. RESULTS: Primary technical success was achieved in 94% of ablation sessions. The median follow-up interval was 15 months (range, 6.2-29.5 mo) during which time local tumor progression was observed in two of 87 tumors (technique effectiveness 98%). Pneumothorax requiring chest tube insertion occurred in 19%; delayed pneumothorax occurred in four patients. No hemoptysis, infection, or other complications were recorded. CONCLUSIONS: High-energy MWA is safe and effective for the destruction of lung tumors.

Osteoid osteoma as a cause of anterior ankle pain in a runner.

We report the case of an osteoid osteoma in the dorsal talar neck of a healthy long-distance runner, masquerading as anterior ankle impingement syndrome. We discuss the diagnosis and successful treatment using percutaneous CT-guided laser photocoagulation. A concise review of the principles of the management of osteoid osteomas is also presented.

Bacteria in sputum of stable severe asthma and increased airway wall thickness.

BACKGROUND: Patients with chronic asthma have thicker intrapulmonary airways measured on high resolution computed tomography (HRCT). We determined whether the presence of lower airway bacteria was associated with increased airway wall thickness. METHODS: In 56 patients with stable severe asthma, sputum specimens obtained either spontaneously or after induction with hypertonic saline were cultured for bacteria and thoracic HRCT scans obtained. Wall thickness (WT) and area (WA) expressed as a ratio of airway diameter (D) and total area, respectively, were measured at five levels. RESULTS: Positive bacterial cultures were obtained in 29 patients, with H. influenzae, P. aeruginosa and S. aureus being the commonest strains. Logistic regression analysis showed that this was associated with the duration of asthma and the exacerbations during the past year. In airways > 2 mm, there was no significant difference in WA (67.5 ± 5.4 vs 66.4 ± 5.4) and WT/D (21.6 ± 2.7 vs 21.3 ± 2.4) between the culture negative versus positive groups. Similarly, in airways (≤ 2 mm), there were no significant differences in these parameters. The ratio of √wall area to Pi was negatively correlated with FEV1% predicted (p < 0.05). CONCLUSIONS: Bacterial colonization of the lower airways is common in patients with chronic severe asthma and is linked to the duration of asthma and having had exacerbations in the past year, but not with an increase in airway wall thickness.

Lung carcinoma with hypertrophic osteoarthropathy in a teenager.

Hypertrophic osteoarthropathy (HOA) characterised by arthralgia, clubbing and periosteal proliferation of long bones, is rarely encountered in children and adolescents. Whereas in adults over 80% of cases are associated with malignancy, in children the majority of cases are due to non-neoplastic causes such as cystic fibrosis, bilary atresia and congenital heart disease. Up to 5% of adults with lung cancer demonstrate signs of HOA. However, lung cancer is extremely uncommon in children and young people. Here we report a case of lung adenocarcinoma in an 18 year old male associated with HOA present both at diagnosis and at subsequent disease progression.

Extracorporeal high intensity focused ultrasound for renal tumours: a 3-year follow-up.

OBJECTIVE: To determine whether primary extracorporeal high-intensity focused ultrasound (HIFU) is safe, feasible and effective for managing small renal tumours. PATIENTS AND METHODS: Although surgery currently remains the standard treatment for localized renal cell carcinoma (RCC), the increasing incidence of small renal cancers has led to a shift towards nephron-sparing surgery, with associated morbidity in 20-25% of cases, and minimally invasive ablative therapies present an alternative management. HIFU results in 'trackless' homogenous tissue ablation and when administered via an extracorporeal device, is entirely noninvasive. The study comprised 17 patients (mean tumour size 2.5 cm) with radiologically suspicious renal tumours who underwent extracorporeal HIFU using the Model-JC System (Chongqing HAIFU™, China), under general anaesthesia with one overnight hospital stay. Real-time diagnostic ultrasonography was used for targeting and monitoring. Patients were followed with a clinical review and gadolinium-enhanced magnetic resonance imaging at 12 days and every 6 months for a mean of 36 months. The outcomes measures were patient morbidity and oncological efficacy of HIFU treatment. RESULTS: Of the 17 patients, 15 were treated according to protocol; two procedures were abandoned due to intervening bowel. There were no major complications related to HIFU. Radiological evidence of ablation was apparent at 12 days in seven of the 15 patients. Before the 6-month follow-up one patient had surgery due to persisting central enhancement. Fourteen patients were evaluated at the 6-month follow-up; eight tumours had involuted (mean 12% decrease in tumour area). Four patients had irregular enhancement on imaging and had alternative therapies. Ten patients remain on follow-up at a mean (range) of 36 (14-55) months after HIFU (mean 30% decrease in tumour area). There was central loss of enhancement in all. CONCLUSIONS: Renal HIFU achieves stable lesions in two-thirds of patients, with minimal morbidity, and might be appropriate in selected cases. Further trials with accurate histological follow-up are essential to fully evaluate this novel technique.

Is it time to consider a role for MRI before prostate biopsy?

The use of MRI in prostate cancer management is controversial and current guidelines underplay its role. Technological advances over the past 5 years, however, demand a re-evaluation of this position. In this article, we propose an increased use of MRI, not only in those with a diagnosis of prostate cancer but also for men before a prostate biopsy. The use of MRI before a biopsy can serve as a triage test in men with raised serum prostate-specific antigen levels, in order to select those for biopsy with significant cancer that requires treatment. This strategy could avoid biopsy, and hence unnecessary treatment, in those with no disease or insignificant cancer. In addition, avoidance of postbiopsy artifact caused by hemorrhage will lead to better local staging accuracy, while determining more accurately the disease burden. This approach could improve risk stratification by selecting those who require adjuvant therapy or dose escalation. Furthermore, MRI evaluation of cancer burden could be important in active surveillance regimens to select those needing intervention.