Feasibility of Detecting Pulmonary Embolism Using Noncontrast MRI

Abstract

Purpose. The purpose of this study was to evaluate the feasibility of detecting pulmonary emboli utilizing noncontrast magnetic resonance imaging techniques in patients with known pulmonary embolism. Materials and Methods. Eleven patients were enrolled in a study to evaluate right ventricular function by cardiac MRI in patients diagnosed with acute pulmonary embolism on CT pulmonary angiogram. Cardiac MRI was performed as soon as possible following pulmonary embolism detection. Two independent observers reviewed the precontrast portion of each MRI, scoring right, left, and lobar arteries as positive or negative for PE. The CTs were reviewed and interpreted in the same manner. Results. MRI was obtained on average of 40 hours after the CT. Forty-eight vessels were affected by PE on CT, 69% of which were identified on MRI. All eight pulmonary emboli located in the right or left pulmonary arteries were detected on MRI. Of the 15 pulmonary emboli that were not detected on MRI, 7 were subsegmental, 6 were segmental, and 2 were located in a branch not included in the MRI field of view. Conclusions. Most pulmonary emboli detected on CT were identified on noncontrast MRI, even though our MRI protocol was not optimized for pulmonary artery visualization.

Role of Non-Contrast MRI in Diagnosis of Pulmonary Embolism

“…MRI study performed by using 1.5 T machine (achieva, philips medical system, Eindhoven, Netherlands) using 8 Channel dedicated phased array cardiac coil and examination protocol was Non-contrast technique and depending on white blood (WB) and black blood (BB) sequences with ECG gating and respiratory gating. This is similar to Mudge et al (1) who used the same technique yet on only 11 patients. Also Kluge et al (9) and Kalb et al (8) tried to evaluate the non-contrast MRA in diagnosis of PE yet as a part of a larger MRI protocol including the use of gadolinium in other sequences of MRI with the CTA was also the reference tool.…”

“…So both sensitivity and specificity of noncontrast MRPA in detection of PE in the main pulmonary trunk, right, left main trunk and lobar divisions were 100% which are higher than the results obtained from Kalb et al (8) who found that the sensitivity of non-contrast MR PA in detection of PE in lobar branches only the ranging from (40-70%) varying according to which side and which lobar branch is involved being 40% only in the lobar branch of the lingula and 70 % at the lower lobar branches , he postulated the low sensitivity at the lobar branch of the lingula to the vascular geometry in this area, in addition to cardiac and respiratory motion effects .our sensitivity results are also higher than the results obtained from Mudge et al (1) who found that the sensitivity of non-contrast MRPA was ranging from (30-100%) being 30 % at the upper lobar branches and 100% at the lower lobar branches. In our study the non-contrast MRPA detected only1 case of PE at the right lower segmental branches out of 7 cases of segmental branches emboli detected by contrast enhanced CTPA, So we found that the specificity of non-contrast MRPA in detection of PE is around 100% and the sensitivity was tested only at the right lower lobe segmental branches being 50%.…”

“…Pulmonary embolism (PE) is a serious condition responsible for significant morbidity and mortality. PE is currently the third leading cause of cardiovascular death worldwide, so it requires prompt diagnosis and treatment to prevent potentially deadly consequences (1) Pulmonary embolism occurs when a blood clot-usually from the leg-travels to the lung and blocks the pulmonary artery or one of its branches (2).…”

Comparison between CT and MRI in the assessment of pulmonary embolism

“…According to other researches, there have been little previous studies of comparison between CT and MRI in regard to diagnosing PE. [12–15]…”

Venous Thromboembolism

“…One advantage that MRI may offer over CTPA is that contrast does not have to be used avoiding radiation and nephrotoxity. The common MRI settings without contrast uses either gradient ECHO or time of fl ight, but in one study when compared with CTPA only had 69 % sensitivity [ 130 ]; however, all the PE in the main pulmonary arteries were detected and it was segmental and subsegmental PE that were missed. The specifi city was 100 %.…”