Supporting capacity management decisions in healthcare using data-driven process simulation.

Healthcare managers are confronted with various Capacity Management decisions to determine appropriate levels of resources such as equipment and staff. Given the significant impact of these decisions, they should be taken with great care. The increasing amount of process execution data - i.e. event logs - stored in Hospital Information Systems (HIS) can be leveraged using Data-Driven Process Simulation (DDPS), an emerging field of Process Mining, to provide decision-support information to healthcare managers. While existing research on DDPS mainly focuses on the fully automated discovery of simulation models from event logs, the interaction between process execution data and domain expertise has received little attention. Nevertheless, data quality issues in real-life process execution data stored in HIS prevent the discovery of accurate and reliable models from this data. Therefore, complementary information from domain experts is necessary. In this paper, we describe the application of DDPS in healthcare by means of an extensive real-life case study at the radiology department of a Belgium hospital. In addition to formulating our recommendations towards the radiology management, we will elaborate on the experienced challenges and formulate recommendations to move research on DDPS within a healthcare context forward. In this respect, explicit attention is attributed to data quality assessment, as well as the interaction between the use of process execution data and domain expertise.

Effect of mechanical stress on magnetic resonance imaging of the sacroiliac joints: assessment of military recruits by magnetic resonance imaging study.

Objective: To assess the baseline condition of the SI joints (SIJs) in healthy individuals without symptoms of back pain and to study the effect of mechanical stress caused by intense physical training on MRI of the SIJs. Methods: Twenty-two military recruits underwent an MRI of the SIJs before and after 6 weeks of intense standardized physical training. Bone marrow oedema and structural lesions were scored based on the Spondyloarthritis Research Consortium of Canada (SPARCC) method, by three trained readers blinded for time sequence and clinical findings. Additionally, fulfilment of the Assessment of SpondyloArthritis international Society (ASAS) definition of a positive MRI was evaluated. Results: At baseline, 9/22 recruits (40.9%) already presented a SPARCC score ⩾1; this number increased to 11/22 (50.0%) at week 6 (P = 0.625). In these patients, the mean (SD) SPARCC score was 2.4 (0.4) at baseline, compared to 3.7 (1.3) at week 6. Overall, the mean (SD) change in SPARCC score over time in all 22 patients was 0.9 (0.6) (P = 0.109). A positive MRI according to the ASAS definition was present in 5/22 recruits (22.7%) at baseline, which increased to 8/22 (36.4%) at follow-up (P = 0.375). Structural lesions were present in 6/22 subjects (27.3%), both at baseline and after 6 weeks of training. Conclusion: A substantial proportion of healthy active individuals without any symptoms of back pain displayed bone marrow oedema lesions on MRI at baseline. However, MRI lesions did not increase significantly after 6 weeks of intensive physical training. Our study underscores the necessity to interpret MRI findings of the SIJs in the appropriate clinical context, even in a young active population.

Whole-body MRI with diffusion-weighted sequence for staging of patients with suspected ovarian cancer: a clinical feasibility study in comparison to CT and FDG-PET/CT.

OBJECTIVES: To evaluate whole-body MRI with diffusion-weighted sequence (WB-DWI/MRI) for staging and assessing operability compared with CT and FDG-PET/CT in patients with suspected ovarian cancer. METHODS: Thirty-two patients underwent 3-T WB-DWI/MRI, (18) F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) and CT before diagnostic open laparoscopy (DOL). Imaging findings for tumour characterisation, peritoneal and retroperitoneal staging were correlated with histopathology after DOL and/or open surgery. For distant metastases, FDG-PET/CT or image-guided biopsies were the reference standards. For tumour characterisation and peritoneal staging, WB-DWI/MRI was compared with CT and FDG-PET/CT. Interobserver agreement for WB-DWI/MRI was determined. RESULTS: WB-DWI/MRI showed 94 % accuracy for primary tumour characterisation compared with 88 % for CT and 94 % for FDG-PET/CT. WB-DWI/MRI showed higher accuracy of 91 % for peritoneal staging compared with CT (75 %) and FDG-PET/CT (71 %). WB-DWI/MRI and FDG-PET/CT showed higher accuracy of 87 % for detecting retroperitoneal lymphadenopathies compared with CT (71 %). WB-DWI/MRI showed excellent correlation with FDG-PET/CT (κ = 1.00) for detecting distant metastases compared with CT (κ = 0.34). Interobserver agreement was moderate to almost perfect (κ = 0.58-0.91). CONCLUSIONS: WB-DWI/MRI shows high accuracy for characterising primary tumours, peritoneal and distant staging compared with CT and FDG-PET/CT and may be valuable for assessing operability in ovarian cancer patients. KEY POINTS: • Whole-body MRI with diffusion weighting (WB-DWI/MRI) helps to assess the operability of suspected ovarian cancer. • Interobserver agreement is good for primary tumour characterisation, peritoneal and distant staging. • WB-DWI/MRI improves mesenteric/serosal metastatic spread assessment compared with CT and FDG-PET/CT. • Retroperitoneal/cervical-thoracic nodal staging using qualitative DWI criteria was reasonably accurate. • WB-DWI/MRI and FDG-PET/CT showed the highest diagnostic impact for detecting thoracic metastases.

Evaluation of a comprehensive pre-procedural screening protocol for COVID-19 in times of a high SARS CoV-2 prevalence: a prospective cross-sectional study.

BACKGROUND: To minimise the risk of COVID-19 transmission, an ambulant screening protocol for COVID-19 in patients before admission to the hospital was implemented, combining the SARS CoV-2 reverse-transcriptase polymerase chain reaction (RT-PCR) on a nasopharyngeal swab, a chest computed tomography (CT) and assessment of clinical symptoms. The aim of this study was to evaluatethe diagnostic yield and the proportionality of this pre-procedural screeningprotocol. METHODS: In this mono-centre, prospective, cross-sectional study, all patients admitted to the hospital between 22nd April 2020 until 14th May 2020 for semi-urgent surgery, haematological or oncological treatment, or electrophysiological investigationunderwent a COVID-19 screening 2 days before their procedure. At a 2-week follow-up, the presence of clinical symptoms was evaluated by telephone as a post-hoc evaluation of the screening approach.Combined positive RT-PCR assay and/or positive chest CT was used as gold standard. Post-procedural outcomes of all patients diagnosed positive for COVID-19 were assessed. RESULTS: In total,528 patients were included of which 20 (3.8%) were diagnosed as COVID-19 positive and 508 (96.2%) as COVID-19 negative. 11 (55.0%) of COVID-19 positive patients had only a positive RT-PCR assay, 3 (15.0%) had only a positive chest CT and 6 (30%) had both a positive RT-PCR assay and chest CT. 10 out of 20 (50.0%) COVID-19 positive patients reported no single clinical symptom at the screening. At 2 week follow-up, 50% of these patients were still asymptomatic. 37.5% of all COVID-19 negative patients were symptomatic at screening. In the COVID-19 negative group without symptoms at screening, 78 (29.3%) patients developed clinical symptoms at a 2-week follow-up. CONCLUSION: This study suggests that routine chest CT and assessment of self-reported symptoms have limited value in the preprocedural COVID-19 screening due to low sensitivity and/or specificity.

Imaging in Myotonic Dystrophy Type 1 - Case Reports.

Myotonic dystrophy type 1 (DM1) is the most common of the muscular dystrophies. It is an autosomal dominant neuromuscular disorder with multisystem involvement, including the central nervous system. Two DNA-proven cases are presented. Patients reported are siblings showing features of DM1 on magnetic resonance imaging (MRI). These features include T2 and FLAIR hyperintensities in the periventricular, deep, and subcortical white matter, with frequent involvement of the anterior temporal lobe. Other features include general brain atrophy and enlarged Virchow-Robin spaces. Subcortical white matter lesions anterior in the temporal lobe are the most specific imaging finding, and a short differential diagnosis is discussed.

Quantification of Al-equivalent thickness of just visible microcalcifications in full field digital mammograms.

Characterization of digital mammography systems is often performed by means of contrast-detail curves using a homogeneous phantom with inserts of different sizes and thicknesses. In this article, a more direct measure of the threshold contrast-detail characteristics of microcalcifications in clinical mammograms is proposed, which also takes into account routine processing and display. The proposed method scores the detectability of simulated microcalcifications with known size and aluminum-equivalent thickness. Thickness estimates, based on x-ray transmission coefficients, were first validated for Al particles. The same approach was then applied to associate Al-equivalent thickness with simulated microcalcifications. Thirty-five mammograms of patients were acquired using a full field digital mammography (FFDM) system operating under standard exposure conditions. Different microcalcifications were simulated using templates of real microcalcifications as described in Med. Phys. 30, 2234-2240 (2003). These templates were first modified such that they simulated a template of the same microcalcification for an ideally sharp detector. They were then adjusted for the imaging characteristics of the FFDM, beam quality, and breast thickness. Microcalcification sizes in the image plane ranged from 200 to 800 microm. Their peak Al-equivalent thickness varied between 70 and 1000 microm. Software phantoms were created. They consisted of 0-10 simulated microcalcifications randomly distributed in 2 cm by 2 cm frames embedded within digital mammograms. Routine processing and printing followed. Three experienced radiologists recorded the locations of the microcalcifications, and confidence ratings were given. Free response receiver operating characteristics (FROC) analysis was performed. Using a binary score, the fractions of detected microcalcifications were plotted as a function of equivalent diameter for the different Al-equivalent thicknesses. Pair-wise agreement of the detected microcalcifications was calculated for the different Al-equivalent thickness groups. The FROC curves of each radiologist indicated similar true positive fractions for a given number of false positives per image. One radiologist applied a more conservative scoring. Detected fractions for the different sizes of the microcalcifications showed the same trend for all observers. In addition, the observer with the least FP also detected less microcalcifications. The pair-wise agreement of the detected microcalcifications was good. The average detected fractions were >0.5 for microcalcifications with equivalent diameter >400 microm and Al-equivalent thickness >400 microm. An average detected fraction >0.5 was also seen for microcalcifications with equivalent diameter <400 microm and equivalent thickness >800 microm. The detected fractions of smaller microcalcifications were <0.5. The results obtained with this method indicate that it may be possible to quantify the performance of a digital mammography detector including processing and viewing for the detection of microcalcifications. We hypothesize that the FROC curves and detected fractions of simulated microcalcifications of different sizes reflect the clinical reality.

Development and validation of a simulation procedure to study the visibility of micro calcifications in digital mammograms.

The visibility of micro calcifications is a determining factor for digital mammography. To address the problem of quantification, we developed a procedure to simulate micro calcifications into real mammograms. First, the shapes, sizes and x-ray transmission coefficients of real micro calcifications were derived from the appearance of biopsy specimens in the raw data of magnified, digital images acquired at 27 kVp and Mo/Mo anode-filter combination. This allowed us to create "ideal templates" of micro calcifications. The x-ray transmissions of the real micro calcifications values were expressed in Al-equivalent thickness. This made it possible to recalculate the x-ray transmission characteristics of a particular ideal template for other x-ray beam qualities. Extra corrections for differences in spatial resolution were based on the presampled two-dimensional modulation transfer functions and on the difference in pixel size. Three radiologists compared the appearance of real and simulated micro calcifications in a two-alternative forced choice (2AFC) evaluation. They perceived no differences between real and simulated lesions. Preliminary results show that it is possible to simulate micro calcifications with well defined characteristics that are indistinguishable from real ones. It should be noted, however, that the full potential of the approach has not been proven. In future work, these templates may be useful to evaluate particular aspects of digital mammograms, such as the effects of processing and of viewing conditions on the visibility of micro calcifications.

Focal sclerosis of semicircular canals with severe DFNA9 hearing impairment caused by a P51S COCH-mutation: is there a link?

HYPOTHESIS: Focal sclerosis of one or more semicircular canals on computed tomographic (CT) scans and a corresponding signal loss on magnetic resonance (MR) imaging are radiologic lesions that are linked to patients who are suffering from advanced otovestibular impairment caused by hereditary DFNA9 hearing loss. BACKGROUND: DFNA9 is a hereditary hearing loss that is characterized by late-onset progressive imbalance and hearing deterioration, caused by mutations in the COCH gene. To date, no radiologic lesions have been associated with this condition. STUDY DESIGN: A retrospective chart review SETTING: Tertiary referral center SUBJECTS: The radiologic data of 9 patients who presented between 2007 and 2012 with otovestibular deterioration caused by a mutation in the COCH gene were reviewed. RESULTS: All 9 subjects were carriers of the same c.151C > T, p.Pro51Ser (P51S) - missense mutation in the COCH gene. In 8 of them similar sclerotic lesions and/or narrowing were demonstrated in one or more semicircular canals on computed tomography CT scan, with a signal loss at corresponding areas on T2-weighted magnetic resonance (MR) images. In 1 patient, the posterior part of the vestibule was also affected. The posterior canals were affected in most cases (58%), compared with the superior (21%) and lateral canals (16%) or the vestibule (5%). Only 68.4% of the lesions on MR images were also visible on CT scans, suggesting a fibrotic process without calcification. Ears presenting radiologic lesions showed significantly more severe hearing loss (median PTA 104 dB HL) compared with unaffected ears (58 dB HL). CONCLUSION: Eight of 9 subjects with the same P51S mutation in the COCH gene showed similar radiologic lesions, affecting the PSCC in the majority of the cases. These radiologic abnormalities occurred in more advanced stages of the otovestibular deterioration, supporting the hypothesis that these lesions might represent the end phase of a low-grade chronic inflammation or protein deposition. A new phenotypic and characteristic radiologic feature of DFNA9 has been discovered.