Imaging considerations for VQ scan and CTPA in suspected PE
| Clinical criteria or concern . | V/Q . | CTPA . |
|---|---|---|
| At risk for reaction to contrast media requiring premedication | + | −* |
| Concern over radiation to breast tissue in women | + | − |
| Renal insufficiency | + | − |
| Suspected VTE recurrence or treatment failure with index PE diagnosed by VQ scan | + | − |
| Suspected VTE recurrence or treatment failure with index PE diagnosed by CTPA | + | +/− |
| Concern over radiation to the fetus, especially first trimester | +/− | +/− |
| Minimizing the risk of missed VTE on initial imaging detected at 3 mo | +/− | +/− |
| Timely result required and both modalities accessible | − | + |
| Alternative or concomitant diagnosis actively sought (eg, malignancy, pneumonia) | − | + |
| Abnormalities present on plain radiography (eg, hyperinflation, pleural effusion or other) | − | + |
| Limited institutional access or expertise in nuclear medicine | − | + |
| Clinical criteria or concern . | V/Q . | CTPA . |
|---|---|---|
| At risk for reaction to contrast media requiring premedication | + | −* |
| Concern over radiation to breast tissue in women | + | − |
| Renal insufficiency | + | − |
| Suspected VTE recurrence or treatment failure with index PE diagnosed by VQ scan | + | − |
| Suspected VTE recurrence or treatment failure with index PE diagnosed by CTPA | + | +/− |
| Concern over radiation to the fetus, especially first trimester | +/− | +/− |
| Minimizing the risk of missed VTE on initial imaging detected at 3 mo | +/− | +/− |
| Timely result required and both modalities accessible | − | + |
| Alternative or concomitant diagnosis actively sought (eg, malignancy, pneumonia) | − | + |
| Abnormalities present on plain radiography (eg, hyperinflation, pleural effusion or other) | − | + |
| Limited institutional access or expertise in nuclear medicine | − | + |
+, preferred; −, suboptimal; +/−, roughly equivalent.
Various preparatory regimens exist to dampen what would be anticipated as a mild or moderate allergic reaction but result in imaging delays.