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170 Chapter 9 Because we could not rely on CA as the gold standard for individual diagnoses either, we created a reference standard that was based on pathologies diagnosed with certainty by either method. chapter5 Since theMIA and CAwere compared to this reference standard, MIA could have an even better accuracy than CA for some pathologies. Missed diagnoses For our MIA we used both MRI and CT, and, by that, benefited from both their specific imaging qualities (e.g. good visualization of organ parenchyma as well as bone and air) and had to deal with both their shortcomings (e.g. image artefacts due to metal parts). 52,103,125,126,132 Even when we evaluated the MRI and CT images together, the detection was not faultless. We sometimes were unable to detect the same lesion on the corresponding images of the other imaging modality. This has occasionally caused difficulties when we aimed to obtain CT-guided tissue biopsies from lesions detected at MRI. In some cases, this problem may have influenced the diagnostic accuracy of the MIA. That some of the CA diagnoses in our cohort were missed macroscopically (e.g. a kidney infarction, an active cystitis, a spleen infarction and a necrotizing hepatitis) may be due to the fact that macroscopy was mainly performed by residents rather than by themore experienced supervising pathologists. If lesions are not recognized on macroscopy, they will not be sampled for histological examination, whereby some diagnoses will be missed. However, in our cohort, there were also diagnoses that had been missed even though the organs had been adequately sampled. Five out of six acute myocardial infarctions and five out of six pneumonias were originally missed at CA, but they turned out to actually be present on the available histological slides. Only one of each was truly missed, and, by contrast, two acute myocardial infarctions were falsely diagnosed. The false negative and false positive cases were corrected during a secondary evaluation, which was initiated based on discrepancies with the MIA findings. Cardiovascular pathologies Cardiovascular diseases (e.g. unsuspected pulmonary emboli and myocardial infarctions) are the leading cause of death in many countries, and not easily detected by MIA. Localized or massive acute myocardial infarction, endocarditis and thrombo-emboli are considered blind spots of the imaging techniques. 57,59,108,109 However, new techniques are being developed to improve accuracy, such as state-of-the-art high resolution MR of the heart, 233,259,chapter 6 coronary optical coherence tomography 43,260 and either PMCT-angiography 118,120,127,133,165,261-263 or, less frequently used, PMMR- angiography. 99 These angiographic techniques either aim to visualize all the vessels