Towards texture accurate slice interpolation of medical images using PixelMiner

Quantitative image analysis models are used for medical imaging tasks such as registration, classification, object detection, and segmentation. For these models to be capable of making accurate predictions, they need valid and precise information. We propose PixelMiner, a convolution-based deep-learning model for interpolating computed tomography (CT) imaging slices. PixelMiner was designed to produce texture-accurate slice interpolations by trading off pixel accuracy for texture accuracy. PixelMiner was trained on a dataset of 7829 CT scans and validated using an external dataset. We demonstrated the model's effectiveness by using the structural similarity index (SSIM), peak signal to noise ratio (PSNR), and the root mean squared error (RMSE) of extracted texture features. Additionally, we developed and used a new metric, the mean squared mapped feature error (MSMFE). The performance of PixelMiner was compared to four other interpolation methods: (tri-)linear, (tri-)cubic, windowed sinc (WS), and nearest neighbor (NN). PixelMiner produced texture with a significantly lowest average texture error compared to all other methods with a normalized root mean squared error (NRMSE) of 0.11 (p < .01), and the significantly highest reproducibility with a concordance correlation coefficient (CCC) ≥ 0.85 (p < .01). PixelMiner was not only shown to better preserve features but was also validated using an ablation study by removing auto-regression from the model and was shown to improve segmentations on interpolated slices.

AB1469 SPANISH TRANSLATION AND CROSS-CULTURAL ADAPTATION OF THE mSQUASH

Background

Regular physical activity is recommended for all patients in the ASAS/EULAR recommendations for the management of axial spondyloarthritis (axSpA). However, there is a lack of outcome measures that assess the amount and type of physical activity in patients with axSpA. For this matter, the modified Short QUestionnaire to Assess Health enhancing physical activity (mSQUASH) was developed and validated, originally in Dutch1.

Objectives

To translate and cross-culturally adapt the mSQUASH into Spanish and to test the equivalence of the translated version in patients with axSpA.

Methods

The mSQUASH was translated into Spanish and then back-translated into Dutch, following forward-backward procedure as described by Beaton2 (Figure 1). Two bi-lingual translators (native speakers for European Spanish) produced independent forward translations of the item content, response options, and instructions of the mSQUASH into Spanish. Both versions were harmonized in a meeting among the Spanish translators, a methodologist and a rheumatologist into a consensual version. Another translator (native speaker for Dutch), blinded for the original version, back translated the synthesized version into Dutch. An expert committee, including all translators, one methodologist and a rheumatologist, reached consensus on discrepancies, ensuring equivalence between the Dutch and Spanish versions, and developed a pre-final version of the Spanish mSQUASH. The field test with cognitive debriefing involved a sample of 10 patients with axSpA covering the full spectrum of the disease -radiographic axSpA (r-axSpA) and non-radiographic axSpA (nr-axSpA)- with different gender, age, disease duration, and educational background. Each patient was interviewed to check understandability, interpretation and cultural relevance of the translation.

Figure 1.

Cross-cultural adaptation of the mSQUASH

Results

The translation process of the mSQUASH was completed without major complications following the forward-backward procedure. The first translation needed several iterations due to small discrepancies in the wording. Back-translation was performed without difficulties, and the expert committee agreed upon a final version of the questionnaire. A total of 10 patients with axSpA participated in the field test (Table 1). Seven were male, mean age (SD) was 38.9 (14.4) years; 6 patients had r-axSpA, 9 were HLA-B27+. Cognitive debriefing showed the Spanish questionnaire to be, relevant, understandable and comprehensive. The preliminary version was accepted with minor modifications. As a result of the interviews, minor spelling errors were corrected, and the wording of the response categories was homogenized (“despacio/ligero”). Besides, the term “colegio”- translated literally from the Dutch “school”- was found not comprehensive enough to reflect possibilities on education (i.e. it does not include university), so it was adapted to “el lugar de estudio”.

Table 1.

Patients’ characteristics

#GenderAgeWorking statusEducationaxSpA subtypeDisease durationHLA-B27DrugBASDAI1Male63WorkingUniversityr-axSpA35 y+NSAIDs2.32Male24StudentSecondaryr-axSpA6 y+NSAIDs03Male37WorkingUniversityr-axSpA5 y+ADA2.54Male66RetiredUniversityr-axSpA23 y+IFN3.15Male29WorkingUniversityr-axSpA11 y+ADA06Female26WorkingUniversitynr-axSpA2 y+NSAIDs-7Male24StudentUniversitynr-axSpA1 y+ETA4.58Male35WorkingUniversityr-axSpA12 y+GOL09Female40WorkingSecondarynr-axSpA4 y+NSAIDs-10Female45UnemployedPrimarynr-axSpA9 y-GOL8.2

Conclusion

The resulting Spanish version of the mSQUASH showed good linguistic and face validity according to the field test, revealing potential for use in both clinical practice and research settings. In order to conclude the cross-cultural adaptation of the mSQUASH into Spanish, the next step is the assessment of psychometric properties of the Spanish version.

References

[1]Beaton DE, et al. Spine. 2000; 25:3186-91

[2]Carbo et al. Semin Arthritis Rheum. 2021; 51:719-27

Disclosure of Interests

Diego Benavent Speakers bureau: Jannsen, Roche, Grant/research support from: Novartis, Andrea Jochems: None declared, DORA PASCUAL-SALCEDO Speakers bureau: Pfizer, Menarini, Takeda, Abvvie., Grant/research support from: Pfizer, Menarini, Takeda, Abvvie., Gijs Jochems: None declared, Chamaida Plasencia Speakers bureau: Pfizer, Abbvie, Lilly, Sandoz, Sanofi, Biogen, Roche and Novartis, Grant/research support from: Pfizer and Abbvie, Sofia Ramiro Speakers bureau: Eli Lilly, MSD, Novartis, UCB, Consultant of: AbbVie, Eli Lilly, MSD, Novartis, Pfizer, UCB, Sanofi, Grant/research support from: AbbVie, Galapagos, Novartis, Pfizer, UCB, Suzanne Arends: None declared, Anneke Spoorenberg Consultant of: AbbVie, Novartis, Pfizer; UCB, Lilly, Grant/research support from: AbbVie, Pfizer, Alejandro Balsa Speakers bureau: Pfizer, Abbvie, Lilly, Galapagos, BMS, Sandoz, Nordic Pharma, Gebro, Roche, Sanofi, UCB, Consultant of: Pfizer, Abbvie, Lilly, Galapagos, BMS, Nordic Pharma, Sanofi, UCB, Grant/research support from: Pfizer, Abbvie, BMS, Nordic Pharma, Gebro, Roche, UCB, Victoria Navarro-Compán Speakers bureau: AbbVie, Eli Lilly, Janssen, MSD, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, Eli Lilly, MSD, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie and Novartis

AB1472 TRANSLATION AND CROSS-CULTURAL ADAPTATION OF THE CORS INTO SPANISH

Background

Rheumatic diseases substantially affect the lives of patients, with complex associations between disease severity and self-perceived health status. In this regard, the Coping with Rheumatic Stressors (CORS) questionnaire was developed to measure how patients with rheumatoid arthritis cope with stressors such as pain or dependence. There is no validated instrument to measure coping in axial spondyloarthritis (axSpA) and therefore the adaptation of the CORS would be of great value.

Objectives

To cross-culturally adapt the CORS into Spanish and to test the conceptual equivalence of the translated version in patients with axSpA.

Methods

A translation of the CORS into Spanish was performed, followed by a back-translation into Dutch, following forward-backward procedure as described by Beaton1(Figure 1). Two bi-lingual translators (native speakers for Spanish), one of them informed of the content of the questionnaire and the other not informed, produced independent forward translations of the item content, response options, and instructions of the CORS into Spanish. Both versions were harmonized in a consensual version. Another translator (native speaker for Dutch), not informed of the concepts used in the questionnaire, back translated the synthesized version into Dutch. An expert committee including all translators, one methodologist and a rheumatologist, held a meeting and reached consensus on discrepancies to develop a pre-final version of the Spanish CORS. The field test with cognitive debriefing involved a sample of 10 patients with axSpA covering the full spectrum of the disease and with different sociodemographic backgrounds.

Figure 1.

Cross-cultural adaptation of the CORS

Results

The translation process of the CORS was completed following the forward-backward procedure, after discussion of the discrepancies throughout the process. The first translation was done without major complications. However, several discrepancies appeared in the back-translation, in which there were minor modifications in the wording in one response option (“muchas veces” to “muy a menudo”) and 15 questionnaire items. As an example, “Ik ga de deur uit”, literally meaning “I go out by the door”, was initially translated as such (“salgo por la puerta”); however, it conceptually represents “I go away”, and it was adapted like this (“me voy a la calle”). Thus, a pre-final consensus version of the CORS was agreed by the expert committee. This pre-final version was field tested in 10 patients with axSpA: mean age (SD) was 38.9 (14.4) years, 7 patients were male, 6 had radiographic axSpA, and 9 were HLA-B27+. The Spanish questionnaire appeared clear and understandable to all patients. However, some minor modifications were proposed in some items (Table 1). As a result of the cognitive debriefing, two changes were implemented (one instruction and one item), whereas two other suggestions did not lead to any change due to minor wording discrepancies with similar conceptual equivalence. The final version of the Spanish CORS is shown at shorturl.at/cimC6.

Table 1.

Cognitive debriefing queries and decisions from the expert committee

Original Dutch itemSpanish translation pre-final# Patient queriesQueriesFinal version(….) aan te geven hoe vaak u het beschreven gedrag uitvoert.(…) indique cuán a menudo usted ha llevado a cabo dicho comportamiento.1Literal discrepancies(…) indique la frecuencia con que usted ha tenido dicho comportamiento.Ik rust op tijd uitMe voy a tiempo a descansar1Literal discrepanciesNo changesIk probeer er het beste van te makenIntento aprovechar al máximo1Literal discrepanciesNo changesIk houd rekening met anderenTengo en cuenta a los demás2Meaning doubtsTengo en consideración a los que me ayudan/cuidan

Conclusion

The Spanish version of the CORS showed good cross-cultural validity and good face validity in patients with axSpA according to the field test. Before the Spanish CORS is implemented, further validation is in progress to test the psychometric properties of the instrument.

References

[1]Beaton DE, et al. Spine. 2000; 25:3186-91

Disclosure of Interests

Diego Benavent Speakers bureau: Jannsen, Roche, Grant/research support from: Novartis, Andrea Jochems: None declared, DORA PASCUAL-SALCEDO Speakers bureau: Pfizer, Menarini, Takeda, Abvvie., Grant/research support from: Pfizer, Menarini, Takeda, Abvvie., Gijs Jochems: None declared, Chamaida Plasencia Speakers bureau: Pfizer, Abvvie, Lilly, Sandoz, Sanofi, Biogen, Roche, Novartis., Grant/research support from: Pfizer, Abvvie., Sofia Ramiro Speakers bureau: Eli Lilly, MSD, Novartis, UC, Consultant of: AbbVie, Eli Lilly, MSD, Novartis, Pfizer, UCB, Sanofi, Grant/research support from: AbbVie, Galapagos, Novartis, Pfizer, UCB, Wim van Lankveld: None declared, Alejandro Balsa Speakers bureau: Pfizer, Abbvie, Lilly, Galapagos, BMS, Sandoz, Nordic Pharma, Gebro, Roche, Sanofi, UCB, Consultant of: Pfizer, Abbvie, Lilly, Galapagos, BMS, Nordic Pharma, Sanofi, UCB, Grant/research support from: Pfizer, Abbvie, BMS, Nordic Pharma, Gebro, Roche, UCB, Victoria Navarro-Compán Speakers bureau: AbbVie, Eli Lilly, Janssen, MSD, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, Eli Lilly, MSD, Novartis, Pfizer, UCB Pharma, Grant/research support from: AbbVie and Novartis

Survival outcomes of patients with advanced melanoma from 2013 to 2017: Results of a nationwide population-based registry

BACKGROUND

The treatment landscape has completely changed for advanced melanoma. We report survival outcomes and the differential impact of prognostic factors over time in daily clinical practice.

METHODS

From a Dutch nationwide population-based registry, patients with advanced melanoma diagnosed from 2013 to 2017 were analysed (n = 3616). Because the proportional hazards assumption was violated, a multivariable Cox model restricted to the first 6 months and a multivariable landmark Cox model from 6 to 48 months were used to assess overall survival (OS) of cases without missing values. The 2017 cohort was excluded from this analysis because of the short follow-up time.

RESULTS

Median OS of the 2013 and 2016 cohort was 11.7 months (95% confidence interval [CI]: 10.4-13.5) and 17.7 months (95% CI: 14.9-19.8), respectively. Compared with the 2013 cohort, the 2016 cohort had superior survival in the Cox model from 0 to 6 months (hazard ratio [HR] = 0.55 [95% CI: 0.43-0.72]) and in the Cox model from 6 to 48 months (HR = 0.68 [95% CI: 0.57-0.83]). Elevated lactate dehydrogenase levels, distant metastases in ≥3 organ sites, brain and liver metastasis and Eastern Cooperative Oncology Group performance score of ≥1 had stronger association with inferior survival from 0 to 6 months than from 6 to 48 months. BRAF-mutated melanoma had superior survival in the first 6 months (HR = 0.50 [95% CI: 0.42-0.59]).

CONCLUSION(S)

Prognosis for advanced melanoma in the Netherlands has improved from 2013 to 2016. Prognostic importance of most evaluated factors was higher in the first 6 months after diagnosis. BRAF-mutated melanoma was only associated with superior survival in the first 6 months.

Infrastructure and distributed learning methodology for privacy-preserving multi-centric rapid learning health care: euroCAT

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Developed and implemented IT infrastructure in 5 radiation clinics across 3 countries.

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Proof-of-principle for ‘big data’ infrastructure and distributed learning studies.

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General framework to execute learning algorithms on distributed data.

Machine learning applications for personalized medicine are highly dependent on access to sufficient data. For personalized radiation oncology, datasets representing the variation in the entire cancer patient population need to be acquired and used to learn prediction models. Ethical and legal boundaries to ensure data privacy hamper collaboration between research institutes. We hypothesize that data sharing is possible without identifiable patient data leaving the radiation clinics and that building machine learning applications on distributed datasets is feasible.

We developed and implemented an IT infrastructure in five radiation clinics across three countries (Belgium, Germany, and The Netherlands). We present here a proof-of-principle for future ‘big data’ infrastructures and distributed learning studies. Lung cancer patient data was collected in all five locations and stored in local databases. Exemplary support vector machine (SVM) models were learned using the Alternating Direction Method of Multipliers (ADMM) from the distributed databases to predict post-radiotherapy dyspnea grade ⩾2. The discriminative performance was assessed by the area under the curve (AUC) in a five-fold cross-validation (learning on four sites and validating on the fifth). The performance of the distributed learning algorithm was compared to centralized learning where datasets of all institutes are jointly analyzed.

The euroCAT infrastructure has been successfully implemented in five radiation clinics across three countries. SVM models can be learned on data distributed over all five clinics. Furthermore, the infrastructure provides a general framework to execute learning algorithms on distributed data. The ongoing expansion of the euroCAT network will facilitate machine learning in radiation oncology. The resulting access to larger datasets with sufficient variation will pave the way for generalizable prediction models and personalized medicine.

Abstract P4-16-12: CARE: A pilot study of the effects of short-term fasting on tolerance to (neo) adjuvant chemotherapy in breast cancer patients

Background:

Preclinical evidence shows that short-term fasting (STS) protects normal cells and makes cancer cells more vulnerable to chemotherapy. This pilot study examines the feasibility and the effects of STS on tolerance to chemotherapy in patients with breast cancer.

Patients and methods:

Eligible patients had histologically confirmed, HER2-negative, early stage breast cancer and adequate bone marrow, liver and renal function. Women receiving (neo) adjuvant TAC courses (docetaxel/adriamycin/cyclophosphamide; day 1, q 3 weeks with G-CSF support at day 2) were randomized to fast 24 hours before and 24 hours after start of chemotherapy or to eat according to the guideline for healthy nutrition. The primary endpoint of the study was to compare neutrophil count after therapy. Secondary endpoints were side effects of chemotherapy, other hematologic counts and chemotherapy-induced DNA damage in leukocytes.

Results:

A total of 13 patients were included of which 7 patients fasted for 48 hours around the chemotherapy infusion (arm A) and 6 patients had a normal diet according to healthy nutrition guidelines (arm B). The median age was 52 years versus 53 years, BMI was 25.5 kg/m2 versus 22.9 kg/m2 and stage III was 43% versus 17% of patients in arms A and B, respectively. Patients were generally motivated to fast and the fasting was well tolerated. Plasma glucose levels were significant lower in fasting patients compared to controls. However, other metabolic parameters showed no significant difference. Fasting did not result in significant differences in neutrophil count or side effects of chemotherapy. Hemoglobin levels and erythrocyte counts after therapy were significantly higher in patients who fasted. Leukocytes of the patients which were isolated at various time points during therapy will soon be analysed for chemotherapy-induced DNA damage and presented at San Antonio.

Conclusion:

This is the first study evaluating the feasibility of 48 hours STS and its impact on side effects of chemotherapy in a homogeneous group of cancer patients. STS was well tolerated and had a beneficial effect on hemoglobin level, but not on experienced side effects. DNA analysis will follow. Larger studies are required to produce more insight into the possible benefits of STS during chemotherapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-16-12.