Essen, Germany
Clinical History
A 23-year-old male presented with progressive exertional dyspnea, New York Heart Association Class III (NYHA III). His medical history included renal transplantation at age 4 due to hemolytic uremic syndrome (HUS) and recent treatment for Epstein Barr Virus (EBV)-associated Burkitt lymphoma with a Rituximab-based chemotherapy regimen, without chest radiation. He was in clinical remission at the time of presentation.
Initial workup revealed newly inverted anterior T waves and an incomplete right bundle branch block (RBBB) on ECG (Figure 1). NT-pro-brain natriuretic peptide (BNP) levels were elevated, though other cardiac biomarkers remained within normal limits. Transthoracic echocardiography (TTE) demonstrated new right ventricular (RV) dilatation (46–48 mm) with reduced systolic function as measured by reduced tricuspid annular plane systolic excursion (TAPSE) of 14–16 mm (normal > 17 mm) (Movie 1). There was no prior cardiac history.
 |
| Figure 1. 12-lead electrocardiogram (ECG) showing newly inverted anterior T waves and incomplete right bundle branch block (RBBB). |
 |
| Movie 1. Parasternal long axis (PLAX) and apical four-chamber TTE views demonstrating right ventricular dilatation and reduced systolic function. |
Due to the combination of unexplained dyspnea, elevated NT-proBNP, and newly reduced RV function on echocardiography, the patient was referred for cardiac magnetic resonance (CMR) to further evaluate right heart structure and function, and to assess for possible coronary ischemia.
CMR Findings
CMR was performed on a Siemens MAGNETOM Sola 1.5T system. The study demonstrated a disproportionate RV enlargement, clearly dominant over the left ventricle (LV), apex-forming, with an indexed RV end diastolic volume (RVEDVi) of 102 ml/m² compared with an indexed LVEDVi of 49 ml/m². The RV free wall was hypertrophied (7 mm, threshold >5 mm), and the right ventricular ejection fraction (RVEF) was mild to moderately reduced at 39% (normal >46%). There was pronounced septal bowing and systolic dyskinesia (Movie 2).
 |
| Movie 2. Balanced steady state free precession (bSSFP) images demonstrate right ventricular enlargement, interventricular septa bowing from right to left and dyskinesia. |
The interventricular septal (IVS) angle was measured at peak systole on a mid ventricular short axis cine, using angle markers placed at the RV insertion points. The resulting angle was 166° (Figure 2), exceeding the established threshold of ≥160°, which has been reported as highly specific for precapillary or combined pulmonary hypertension (PH).[1]
 |
| Figure 2. Mid-ventricular short-axis cine image illustrating (interventricular septal) IVS angle measurement at peak systole. The IVS angle measured 166°, exceeding the diagnostic threshold of ≥160°, consistent with precapillary or combined pulmonary hypertension. |
The pulmonary artery (PA)–to–aorta (AO) diameter ratio, measured in the same axial plane at the level of the PA bifurcation, was 1.60 (Figure 3)—well above the diagnostic threshold of >1.0 for pulmonary hypertension [2]. This finding reflects elevated pulmonary pressures and is associated with right ventricular overload. Pulmonary artery dilation was further confirmed by the absolute PA diameter (3.34 cm), which exceeds the upper normal limit for males (~33 mm) as per published reference ranges.[3]
 |
| Figure 3. Axial Volumetric Interpolated Breath-hold Examination (VIBE) image at the level of the pulmonary artery (PA) bifurcation showing a dilated main pulmonary artery (3.34 cm) and an ascending aorta (AO) of 2.09 cm, yielding a PA-to-Ao ratio of 1.60. This exceeds the diagnostic threshold of >1.0 for pulmonary hypertension and the normal upper limit for MPA diameter in men (~32.6 mm), confirming pulmonary artery dilation. |
Native T1 mapping demonstrated elevated septal values, and late gadolinium enhancement (LGE) was observed at the RV insertion points and within the mid-septum, suggesting mechanical wall stress and interstitial fibrosis (Figure 4).
 |
| Figure 4. Elevated T1 mapping values (left) of the interventricular septum (IVS) and late gadolinium enhancement at the inferior right ventricular insertion point (right) suggestive of interstitial fibrosis and mechanical wall stress. |
Flow quantification revealed no evidence of a left to right shunt, with nearly identical stroke volumes in the pulmonary artery and aorta (both ~36 ml). The slow flow score was 4/5; (Figure 5), based on persistent intraluminal signal in four of five predefined pulmonary arterial segments on black blood imaging—a semiquantitative marker associated with impaired pulmonary flow dynamics in PH.[4]
 |
| Figure 5. Black-blood axial image for slow-flow assessment. Persistent intraluminal signal was observed in 4 out of 5 predefined pulmonary artery segments, corresponding to a slow flow score of 4/5—supporting impaired pulmonary hemodynamics. |
Two validated CMR regression models were used to estimate mean pulmonary arterial pressure (mPAP) in this case.[5] Both rely on the IVS angle and RV mass index; Model 1 additionally includes the slow flow score (based on signal persistence in 5 PA segments), while Model 2 uses PA diastolic area. Using Model 1 (mPAP = −179 + loge[IVS angle] × 42.7 + log₁₀[RVMI] × 7.57 + slow flow × 3.39), we estimated an mPAP of ~55 mmHg. Model 2, which substitutes PA area for slow flow score, yielded a nearly identical result.
Stress perfusion imaging showed no evidence of myocardial ischemia.
Conclusion
CMR provided critical diagnostic clarity in this case of suspected pulmonary hypertension (PH). It confirmed severe RV dysfunction and structural remodeling, identified characteristic tissue alterations consistent with PH, and enabled accurate noninvasive estimation of mPAP. CMR-derived mPAP (~55 mmHg) closely matched the invasive measurement obtained during right heart catheterization (mPAP 60 mmHg), which confirmed precapillary PH.
Although the patient was in remission and had no history of chest radiation, a potential link between prior chemotherapy and vascular remodeling cannot be excluded.
The patient was referred to a PH specialty center for Group 1 PAH (Table 1) and started on initial dual oral therapy with an endothelin receptor antagonist (ambrisentan) and a phosphodiesterase-5 inhibitor (tadalafil). At follow-up, he reported improved exercise tolerance and NYHA class had improved from III to I.
 |
| Table 1. Clinical Classification of Pulmonary Hypertension (PH). |
Perspective
Based on the clinical background and CMR findings, the diagnosis is consistent with precapillary pulmonary arterial hypertension (PAH, Group 1, Table 1).[6] The IVS angle of 166°, severe RV remodeling, and absence of left heart disease or lung pathology strongly support this classification. However, in light of the patient’s history of renal transplantation and EBV-associated lymphoma, a multifactorial component (Group 5 PH) was also considered. Comprehensive workup, including HIV testing (negative), pulmonary function testing, and high resolution computed tomography ruled out postcapillary and parenchymal lung disease or pulmonary veno-occlusive disease (PVOD). Genetic testing for heritable PAH is ongoing.
While right heart catheterization remains the gold standard, this case highlights how CMR can provide a comprehensive, noninvasive assessment of pulmonary hypertension by integrating structural, functional, hemodynamic, and tissue-based information in a single modality. In this patient, CMR not only identified the features of precapillary PH but also excluded myocardial ischemia as a differential through normal stress perfusion imaging.
The IVS angle, measured at peak systole on short‑axis cine using markers placed at the RV insertion points, has shown strong correlation with elevated RV pressures and is increasingly recognized as a useful noninvasive marker of precapillary PH.[1] Slow‑flow scoring, based on signal persistence in predefined pulmonary arterial segments on black‑blood sequences, provides an additional semiquantitative indicator of impaired pulmonary hemodynamics.[4]
With advancing validation of CMR-derived pressure estimates, noninvasive diagnosis and longitudinal assessment of PH may become increasingly reliable—potentially reducing the need for invasive testing in selected patients.
Click here for a link to the entire CMR on CloudCMR
References
- Johns CS, et al. Interventricular Septal Angle and the Diagnosis of Pulmonary Hypertension by Cardiac MRI. Radiology. 2018;289(1):61–68.
- Burman ED, Keegan J, Kilner PJ. Pulmonary artery diameters, cross sectional areas and area changes measured by cine cardiovascular magnetic resonance in healthy volunteers. J Cardiovasc Magn Reson. 2016 Mar 3;18:12.
- Kawel-Boehm N, et al. Reference ranges (“normal values”) for cardiovascular magnetic resonance (CMR) in adults and children: 2020 update. J Cardiovasc Magn Reson. 2020;22(1):87
- Swift AJ, Rajaram S, Marshall H, Condliffe R, Capener D, Hill C, Davies C, Hurdman J, Elliot CA, Wild JM, Kiely DG. Black blood MRI has diagnostic and prognostic value in the assessment of patients with pulmonary hypertension. Eur Radiol. 2012 Mar;22(3):695-702.
- Swift AJ, Rajaram S, Condliffe R, Capener D, Hurdman J, Elliot CA, Wild JM, Kiely DG. Diagnostic accuracy of cardiovascular magnetic resonance imaging of right ventricular morphology and function in the assessment of suspected pulmonary hypertension results from the ASPIRE registry. J Cardiovasc Magn Reson. 2012 Jun 21;14(1):40.
- Humbert M, et al. 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension. Eur Heart J. 2022;43(38):3618–3731.
Case Prepared by:
Eddie Hulten, MD, MPH, FACC, FACP, FSCMR, FSCCT, FASNC
Brown University Health Cardiovascular Institute
Rhode Island, the Miriam and Newport Hospitals
Warren Alpert Medical School, Brown University
