New Insights in Abdominal Pain in Paroxysmal Nocturnal Hemoglobinuria (PNH): A MRI Study

Abstract

Introduction: Abdominal pain in PNH has never been investigated by in-vivo imaging studies. With MRI, we aimed to assess mesenteric vessels flow and small bowel wall perfusion to investigate the ischemic origin of abdominal pain.

Materials and methods: Six PNH patients with (AP) and six without (NOP) abdominal pain underwent MRI. In a blinded fashion, mean flow (MF, quantity of blood moving through a vessel within a second, in mL·s-1) and stroke volume (SV, volume of blood pumped out at each heart contraction, in mL) of Superior Mesenteric Vein (SMV) and Artery (SMA), areas under the curve at 60 (AUC60) and 90 seconds (AUC90) and Ktrans were assessed by two operators.

Results: Mean total perfusion and flow parameters were lower in AP than in NOP group. AUC60: 84.81 ± 11.75 vs. 131.73 ± 18.89 (P < 0.001); AUC90: 102.33 ± 14.16 vs. 152.58 ± 22.70 (P < 0.001); Ktrans: 0.0346 min-1 ± 0.0019 vs. 0.0521 ± 0.0015 (P = 0.093 duodenum, 0.009 jejunum/ileum). SMV: MF 4.67 ml/s ± 0.85 vs. 8.32 ± 2.14 (P = 0.002); SV 3.85 ml ± 0.76 vs. 6.55 ± 1.57 (P = 0.02). SMA: MF 6.95 ± 2.61 vs. 11.2 ± 2.32 (P = 0.07); SV 6.52 ± 2.19 vs. 8.78 ± 1.63 (P = 0.07). We found a significant correlation between MF and SV of SMV and AUC60 (MF:ρ = 0.88, P < 0.001; SV: ρ = 0.644, P = 0.024), AUC90 (MF: ρ = 0.874, P < 0.001; SV:ρ = 0.774, P = 0.003) and Ktrans (MF:ρ = 0.734, P = 0.007; SV:ρ = 0.581, P = 0.047).

Conclusions: Perfusion and flow MRI findings suggest that the impairment of small bowel blood supply is significantly associated with abdominal pain in PNH.

Fig 1. Assessment of mean flow (MF) and stroke volume (SV).

In Phase-contrast sequences, elliptic ROIs were manually positioned on the superior mesenteric vein (SMV) and artery (SMA) in order to obtain curves of velocity and flow rate versus time.

Fig 2. Assessment of small bowel wall perfusion.

To calculate MRI perfusion parameters, AUC₆₀, AUC₉₀ and K^trans, elliptic ROIs were positioned in different segments of the small bowel wall, particularly on proximal and distal jejunum and proximal, middle and distal ileum, as showed in this figure.

Fig 3. AUC₆₀ and AUC₉₀ in duodenum, jejunum and ileum.

The horizontal axis represents the patients without (0) and with (1) abdominal pain; the vertical axis represents the AUC₆₀ (darker colors) and AUC₉₀ (lighter colors) values in duodenum (blue), jejunum (green) and ileum (cyan). **: P<.01; Errors bars: 95% of confidence interval.

Fig 4. K^trans in duodenum, jejunum and ileum.

The horizontal axis represents the PNH patients without (0) and with (1) abdominal pain; the vertical axis represents the K^trans values (min^-1) in duodenum, jejunum and ileum. **: P<.01; Errors bars: 95% of confidence interval.

Fig 5. MF and SV in the mesenteric venous (SMV) and arterial (SMA) compartment.

The horizontal axis represents the PNH patients without (0) and with (1) abdominal pain; the vertical axis represents the MF and SV values on superior mesenteric vein (SMV, dark blue) and artery (SMA, light blue). *: P<.05; **: P<.01; Errors bars: 95% of confidence interval.

Fig 6. Spearman rank correlation analysis.

Correlation between MRI perfusion parameters (on the horizontal axis)—AUC₆₀ (A), AUC₉₀ (B), and K^trans (C)—in the whole small bowel—of PNH patients and MF of SMV (on the vertical axis).

Fig 7. Spearman rank correlation analysis.

Correlation between MRI perfusion parameters (on the horizontal axis)—AUC₆₀ (A), AUC₉₀ (B), and K^trans (C)—in the whole small bowel—of PNH patients and SV of SMV (on the vertical axis).

Fig 8. Spearman rank correlation analysis.

Correlation between MRI perfusion parameters (on the horizontal axis)—AUC₆₀ (A), AUC₉₀ (B), and K^trans (C)—in the whole small bowel—of PNH patients and MF of SMA (on the vertical axis).

Fig 9. Spearman rank correlation analysis.

Correlation between MRI perfusion parameters (on the horizontal axis)—AUC₆₀ (A), AUC₉₀ (B), and K^trans (C)—in the whole small bowel—of PNH patients and SV of SMA (on the vertical axis).