Julius Renne MD, Presenter: Nothing to Disclose

Reemt Nieland, Abstract Co-Author: Nothing to Disclose

Jan Hinrichs MD, Abstract Co-Author: Nothing to Disclose

Christian Olaf Schoenfeld MD, Abstract Co-Author: Nothing to Disclose

Marcel Gutberlet DiplPhys, Abstract Co-Author: Nothing to Disclose

Andreas Voskrebenzev, Abstract Co-Author: Nothing to Disclose

Marius Hoeper, Abstract Co-Author: Nothing to Disclose

Tobias Welte MD, Abstract Co-Author: Nothing to Disclose

Serghei Cebotari MD, Abstract Co-Author: Nothing to Disclose

Axel Haverich, Abstract Co-Author: Nothing to Disclose

Peter Michael Jakob PhD, Abstract Co-Author: Nothing to Disclose

Frank K. Wacker MD, Abstract Co-Author: Research Grant, Siemens AG Research Grant, Pro Medicus Limited

Jens Vogel-Claussen MD, Abstract Co-Author: Nothing to Disclose

This study aims to explore pulmonary oxygen-enhanced MRI in patients with CTEPH to detect changes in regional blood oxygenation after PEA compared to healthy controls.

After approval of the institutional review board 16 patients with CTEPH and 12 healthy controls were included. MRI was performed at 1.5T using an inversion recovery snapshot fast low-angle shot (FLASH) sequence for T1 mapping at room air and 100% oxygen. CTEPH patients underwent MRI pre and 7-24 days post PEA. Controls received two MRI 7 days apart. A minimum of six coronal slices (15mm slice thickness, 5mm gap) were acquired. Mean T1 value, coefficient of variation under room air and 100% oxygen, and a previously established marker for ventilation, oxygen diffusivity and blood oxygenation -the oxygen transfer function (OTF)- were calculated for the lungs. OTF=((1/T1100%O2)-(1/T121%O2))/(C100%O2-C21%O2) Mean±SD, t-test.

All healthy controls (29y ±7y) and 14 of the 16 CTEPH patients (53y ±15y) completed MRI scans. Mean T1 values under room air and 100% O2 were significantly lower in CTEPH patients compared to controls (room air: 1250±51ms vs. 1097±63ms, p=0.0001; O2: 1093±38ms vs. 974±53ms, p=0.0001). The coeff. of variation was significantly higher in patients with CTEPH (room air: 4.9±0.9 vs. 12.2±3.2, p=0.0001; O2: 5.9±2 vs 12.6±3.8, p=0.0001). OTF was not significantly different between patients and controls (p=0.55), and did not change at the 2nd MRI for controls (p=0.47) nor after PEA (p=0.14) in the CTEPH group, despite a significant decrease in mPAP after PEA (mean difference -18.7±15mmHg (-44%), p=0.008) and improvement of parenchymal perfusion (mean difference +18.5±17ml/min/100ml (+51%), p=0.0025).

Oxygen-enhanced MRI shows significantly decreased and more heterogeneous T1-values of the lungs in patients with CTEPH compared to normal controls, which reflects the mosaic perfusion pattern in CTEPH. However, OTF was not significantly different between controls and CTEPH patients nor after PEA, indicating that OTF reflects predominantly regional ventilation and oxygen diffusion into the alveolar interstitium rather than improvement in regional blood oxygenation after PEA.

The current study shows that T1 mapping MRI-derived OTF predominantly reflects changes of oxygen within the lung parenchyma and is not applicable for monitoring regional blood oxygenation changes in patients with CTEPH after PEA.

Renne, J, Nieland, R, Hinrichs, J, Schoenfeld, C, Gutberlet, M, Voskrebenzev, A, Hoeper, M, Welte, T, Cebotari, S, Haverich, A, Jakob, P, Wacker, F, Vogel-Claussen, J, Oxygen-enhanced Pulmonary MRI in Patients with Chronic Thromboembolic Pulmonary Hypertension (CTEPH) Pre and Post Pulmonary Endarterectomy (PEA) Compared to Healthy Controls.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045551.html