Clinical and imaging differences between Stanford Type B intramural hematoma-like lesions and classic aortic dissection

Abstract

Background: Intramural hematoma (IMH) and Aortic dissection (AD) have overlapping features. The aim of this study was to explore the differences between them by comparing the clinical manifestations and imaging features of patients with acute Stanford type B IMH-like lesions and acute Stanford type B AD (ATBAD).

Methods: This study retrospectively analysed the clinical and computed tomography angiography (CTA) imaging data of 42 IMH-like lesions patients with ulcer-like projection (ULP) and 38 ATBAD patients, and compared their clinical and imaging features.

Results: (1) The IMH-like lesions patients were older than the ATBAD patients (64.2 ± 11.5 vs. 50.9 ± 12.2 years, P < 0.001). The D-dimer level in the IMH-like lesions group was significantly higher than that in the ATBAD group (11.2 ± 3.6 vs. 9.2 ± 4.5 mg/L, P < 0.05). The incidence rate of back pain was significantly higher in the ATBAD group than in the IMH-like lesions group (71.1% vs. 26.2%, P < 0.05). (2) The ULPs of IMH-like lesions and the intimal tears of ATBAD were concentrated in zone 4 of the descending thoracic aorta. The ULPs of IMH-like lesions and the intimal tears of ATBAD were mainly in the upper quadrant outside the lumen (64.3% vs. 65.8%, P > 0.05). (3) The maximum diameter of the ULPs in IMH-like lesions was smaller than that of the intimal tears in ATBAD (7.4 ± 3.4 vs. 10.8 ± 6.8 mm, P = 0.005). The lumen compression ratio in the ULPs plane and the maximum compression ratio of the aortic lumen in the IMH-like lesions group were smaller than that in the ADBAD group (P < 0.05). Fewer aortic segments were involved in IMH-like lesions patients than in ATBAD patients (5.6 ± 2.2 vs. 7.1 ± 1.9 segments, P < 0.005). The IMH-like lesions group had less branch involvement than that of the ATBAD group (P < 0.001).

Conclusion: The degree of intimal tears, lumen compression ratio, extent of lesion involvement, and impact on branch arteries in ATBAD are more severe than that of IMH-like lesions. But for the ULPs of IMH-like lesions and intimal tears of ATBAD, they have astonishing similarities in the location of the partition and the lumen quadrant, we have reason to believe that intimal tear is the initial factor in the pathogenesis of this kind of disease, and their clinical and imaging manifestations overlap, but the severity is different. Concerning similarities between these two conditions, these two may be a spectrum of one disease.

Keywords: Acute aortic syndrome; CT angiography; IMH-like lesions; Intramural hematoma.

Fig. 1

Imaging manifestations of IMH, ULP, and AD. (A) ATBIMH: Aortic arch and the surrounding area of the descending thoracic aorta without contrast filling. (B) ATBIMH around the descending thoracic aorta with ULP (white arrow). (C) Classical ATBAD manifestations: a free intimal flap and both true and false lumens. ATBIMH, acute type B aortic intramural haematoma; ATBAD, acute type B aortic dissection; ULP, ulcer-like projection

Fig. 2

Measurement of the compression ratio of the aortic lumen using multiple planes. A 52-year-old woman presented with ATBAD. Since the intimal tear was located in the tortuosity of the aorta. The location of the intimal tear, its distance from the left subclavian artery, and the compression ratio of the aortic lumen (73.81%) were determined by three-dimensional double-oblique MPR reconstruction

Fig. 3

Quadrant distribution pattern of intimal tears in IMH and AD. The blue line runs along the main axis of the artery and the red line runs along the vertical line along the main axis of the artery. (A,E) The intimal tear was in the right quadrant. (B,F) The intimal tear was in the lower quadrant; (C,G) The intimal tear was in the upper quadrant; (D,H) The intimal tear was located in the left quadrant

Fig. 4

Society for Vascular Surgery and Society of Thoracic Surgeons reporting standards for type B aortic dissection

Fig. 5

Manifestations of branch involvement and malperfusion complications in ATBIMH. A-D show the imaging manifestations of static obstructions caused by ATBIMH. (A) Haematoma involving the left renal artery and normal left renal perfusion. (B) Haematoma involving the right renal artery orifice, with no abnormal perfusion in the right kidney. (C) Haematoma involving the left renal artery orifice with normal perfusion in the left kidney. (D) The ruptured orifice of the right renal artery, with no ischaemic changes in the right renal artery