The PhD defense will take place

Friday March 10th, 2023
Time: 13.00
Place: Aalborg Universitetshospital, Auditorie Syd

After the defense there will be held a reception. All are welcome.

About the PhD thesis

Introduction

Metastasis to bone is the third most frequent localization after lung and liver. Early and accurate detection of bone metastases is crucial for treatment and thus for morbidity and mortality. Diagnostic imaging such as X-ray, CT, MRI, bone scintigraphy and PET-CT play an important role in early and accurate detection.

Purpose

The purpose of this Ph.D. is to provide valid documentation on the diagnostic accuracy of relevant imaging methods for the detection of bone metastases exclusively using bone biopsy as gold standard. At the same time, we wanted to investigate whether accuracy was influenced by access to and the sequence of previous imaging examinations. Finally, we wanted to document that a bone biopsy diagnosis is in fact a valid gold standard reference.

Material and method

The PhD studies were carried out as a retrospective consecutive cohort study of bone biopsy material collected via Aalborg University Hospital's Department of Pathology by computer search of biopsy material registered in SNOMED (Systematized Nomenclature of Medicine) as T10* and T11* codes for cytological and histological bone biopsies respectively in the period from 1 January 2011 to 31 July 2013.

In the examination of the diagnostic accuracy, 409 biopsies were included and the diagnosis on the imaging examinations 6 month prior to the biopsy was reviewed and compared to the biopsy diagnosis. In the next study, 216 bone biopsies were included with at least 2 different imaging examinations. The imaging accuracy of the included examinations with or without another prior imaging examination and the possible influence of the sequence of these were investigated.

Finally, we followed up on 215 benign bone biopsies for two years after the first benign biopsy diagnosis by looking at the diagnoses from the same anatomical location from additional biopsies and/or imaging studies and/or clinical information in order to be able to categorize the first biopsy as truly benign, truly malignant or ambiguous.

Results

The sensitivity of MRI and FDG-PET/CT proved significantly better than CT, which had a better specificity; in general, these modalities were significantly more accurate than X-ray and bone scintigraphy. The sensitivity for osteolytic and mixed lesions was significantly higher for MRI and PET/CT than for CT, which was not the case for osteosclerotic lesions. For spine lesions, MRI showed the significantly best sensitivity, which was not the case for lesions in the other parts of the skeleton. We could not document a significant difference in the diagnostic accuracy of the imaging examinations, regardless of whether they were preceded by another modality or not, but the sequence analyzes indicated that the greater the diagnostic accuracy of a given modality is assumed to be, the greater is the risk of affecting the accuracy of subsequent imaging modalities. Finally, we found that a benign bone biopsy can be considered a valid criterion for the absence of bone metastases, as 98% of the benign biopsies proved to be truly benign 2 years after the first biopsy.

Conclusion

This PhD thesis has for the first time documented that MR and PET/CT are the most accurate modalities for the detection of bone metastases compared to the gold standard, bone biopsy, which we have also documented can actually be considered a gold standard. We have not been able to show that it has any significant impact on the diagnostic accuracy whether there is access to prior imaging or not, however there is a trend towards that the greater diagnostic accuracy a given modality is assumed to have, the greater the risk of affecting the accuracy when analyzing subsequent image modalities.