The addition of CT to SPECT enables V/Q detection of conditions other than PE (such as radiation therapy induced changes, emphysema, and extrinsic vascular compression from conditions such as neoplasm or mediastinal adenopathy). However, this use remains experimental, and it is not rated as a separate imaging study. Variant 4: Suspected pulmonary embolism. Pregnant patient. Initial imaging. Pregnancy frequently alters the diagnostic strategy for patients with clinically suspected PE, and thus it is considered as a separate variant. For guidance on pregnant patients, please refer to the Safety Considerations in Pregnant Patients section below. Suspected Pulmonary Embolism Radiography Chest Although radiographs are neither sensitive nor specific, the role in pregnancy becomes more relevant when compared to the other variants. The rationale is that an alternative diagnosis may be found, and for patients without clinical evidence of lower extremity DVT, radiography can inform the choice between CTPA and V/Q scanning as a second imaging test. CTPA Although the CTPA acquisition may be modified [62-64] for the physiology of pregnancy, CTPA is commonly performed. In a study involving pregnant women with high pretest probability and those with intermediate probability and positive D-dimer followed by negative bilateral lower extremity US who were evaluated with CTPA, the positive rate was 5.7% (19 of 332), and the indeterminate rate was 6.9% (23 of 332) [65]. CT Chest With IV Contrast When IV contrast is given during the CT acquisition, the study should be performed as a CTPA. There is no relevant literature to support the use of CT chest with IV contrast for suspected PE in a pregnant patient. CT Chest Without and With IV Contrast When IV contrast is given during the CT acquisition, the preferred protocol is CTPA. There is no relevant literature to support the use of CT chest without and with IV contrast for suspected PE in a pregnant patient.
Suspected Pulmonary Embolism PCAs. The addition of CT to SPECT enables V/Q detection of conditions other than PE (such as radiation therapy induced changes, emphysema, and extrinsic vascular compression from conditions such as neoplasm or mediastinal adenopathy). However, this use remains experimental, and it is not rated as a separate imaging study. Variant 4: Suspected pulmonary embolism. Pregnant patient. Initial imaging. Pregnancy frequently alters the diagnostic strategy for patients with clinically suspected PE, and thus it is considered as a separate variant. For guidance on pregnant patients, please refer to the Safety Considerations in Pregnant Patients section below. Suspected Pulmonary Embolism Radiography Chest Although radiographs are neither sensitive nor specific, the role in pregnancy becomes more relevant when compared to the other variants. The rationale is that an alternative diagnosis may be found, and for patients without clinical evidence of lower extremity DVT, radiography can inform the choice between CTPA and V/Q scanning as a second imaging test. CTPA Although the CTPA acquisition may be modified [62-64] for the physiology of pregnancy, CTPA is commonly performed. In a study involving pregnant women with high pretest probability and those with intermediate probability and positive D-dimer followed by negative bilateral lower extremity US who were evaluated with CTPA, the positive rate was 5.7% (19 of 332), and the indeterminate rate was 6.9% (23 of 332) [65]. CT Chest With IV Contrast When IV contrast is given during the CT acquisition, the study should be performed as a CTPA. There is no relevant literature to support the use of CT chest with IV contrast for suspected PE in a pregnant patient. CT Chest Without and With IV Contrast When IV contrast is given during the CT acquisition, the preferred protocol is CTPA. There is no relevant literature to support the use of CT chest without and with IV contrast for suspected PE in a pregnant patient.