"Signal characteristics will vary depending on the age of blood. Post-contrast sequences may identify an underlying mass or vascular cause 8."
Line 23:68·Only use medical adjectival hyphens where the letters at the end and start of the compound word are the same, e.g. post-transplant. In this case, don't use the hyphen: 'Post-contrast'.
Semicolons
suggestion
"due to an underlying associated lesion (most common cause; 60-65% of cases 7,8)"