Diagnostic value of dual-energy CT in detecting irreversible transmural intestinal necrosis in patients with acute occlusive mesenteric ischemia

doi:10.21203/rs.3.rs-4851239/v1

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Research Article

Diagnostic value of dual-energy CT in detecting irreversible transmural intestinal necrosis in patients with acute occlusive mesenteric ischemia

https://doi.org/10.21203/rs.3.rs-4851239/v1

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Background

Irreversible transmural intestinal necrosis (ITIN) is associated with high mortality rates in patients with acute occlusive mesenteric ischemia (AOMI). However, the important radiographic predictors of ITIN remain unknown. This study evaluated the diagnostic value of dual-energy CT (DECT) for ITIN in AOMI.

Methods

The cases and CT images of 102 patients with clinically diagnosed AOMI (including 48 ITIN) from January 2012 to January 2022 were retrospectively collected. The CT scans included both MDCT and DECT. Two radiologists independently completed the subjective visual assessment of CT signs related to AOMI. DECT scans the portal vein phase raw data to reconstruct a 120 kVp mixed energy image, 50 keV virtual monoenergetic imaging (VMI), and iodine map. Objective parameters, including CT values (CT 50 keV lesion, CT 50 keV normal/lesion) and iodine concentrations (IC lesion and IC normal/lesion), were quantified. Furthermore, multivariate logistic regression, receiver operating characteristic (ROC) curves, and area under the curve (AUC) values were used to evaluate the subjective/objective indicators in predicting ITIN.

Results

Regarding subjective signs, logistic regression analysis revealed reduced or absent bowel wall enhancement (odds ratio [OR] = 5.576, 95% confidence interval [CI]: 1.547–20.093), bowel dilation (OR = 11.613, 95% CI: 3.790–35.586), and parenchymatous organ infarction (OR = 4.727, 95% CI: 1.536–14.551) were independent risk factors for the ITIN. CT subjective signs had a high diagnostic efficacy for ITIN (AUC = 0.853). The two DECT objective parameters also exhibited excellent diagnostic value for ITIN, with an AUC of 0.79, a CT cutoff value of CT _{50keV normal/lesion} = 2.81, and an AUC of 0.777 with a cut-off value of IC _{normal/lesion} = 2.39. Importantly, the Delong test showed that there was no significant difference in the efficacy of subjective CT signs and objective DECT parameters (p > 0.05), indicating that the two objective parameters could replace CT signs in predicting ITIN. Furthermore, we observed that IC _{normal/lesion} combined with subjective signs (bowel dilation and parenchymatous organ infarction) had the highest predictive performance (AUC = 0.896), sensitivity (100%), and specificity (70.83%).

Conclusion

IC _{normal/lesion} (DECT-based features) combined with CT signs showed favorable predictive performance for ITIN in AOMI, which may help clinicians develop timely treatment strategies.

Acute mesenteric ischemia

irreversible transmural intestinal necrosis

dual-energy CT

virtual monoenergetic imaging

iodine concentration

Acute mesenteric ischemia (AMI) is caused by a sudden interruption in blood supply to the intestine, which can result in cellular damage and intestinal ischemic injury. If not treated promptly, it usually develops into necrosis of the intestinal wall, leading to death [1]. The main causes of AMI were further defined as occlusive ischemia (AOMI, arterial embolism, arterial thrombosis, and venous thrombosis; accounts for 2/3 of cases) and non-occlusive ischemia [2]. In general, the overall incidence of AMI is low, accounting for 0.09–0.2% of all acute admissions to the emergency department, and is a rare cause of abdominal pain. However, it has a high mortality rate of approximately 50–80% [3]. AOMI can be categorized into two stages (early and late) and is associated with different prognoses. In the early ischemic stage, lesions are reversible and conservative management or endovascular techniques are essential. Advanced disease is characterized by irreversible transmural intestinal necrosis (ITIN), which requires surgical resection of the necrotic intestinal wall to control disease progression [4]. Clinical research has found that if left untreated or treated too late, the probability of ITIN development in patients with AOMI increases rapidly from 0–82% within 24 h, followed by a sharp increase in mortality [5]. Therefore, rapid diagnosis and intervention are essential to limit patient mortality. However, accurate diagnosis of ITIN is challenging because of its non-specific clinical manifestations.

Radiologists play a crucial role in the rapid diagnosis of AMI. According to the current guidelines, multidetector computed tomography (MDCT) is recommended as the first-line method for assessing AMI [6]. Previous studies have shown that the MDCT signs in patients with AMI are associated with ITIN. For example, Calame et al. reported that AOMI was characterized by reduced or absent bowel wall enhancement and less mesenteric fat stranding [7]; Tang et al. found that superior mesenteric artery (SMA) thrombus density on MDCT was considered an independent risk factor for ITIN, and SMA > 36.2 Hounsfield units (HU) can predict the occurrence of thromboembolic ITIN [8]. Although MDCT has high sensitivity and specificity for the diagnosis of ischemia caused by arterial and venous occlusion (approximately 90%), it has low sensitivity for the prediction of obstruction and ITIN (approximately 49%) [9]. Dual-energy CT (DECT) has emerged as a new tool for evaluating AMI. DECT utilizes X-ray attenuation at two different photon energy levels (low and high energy) to characterize tissue composition [10]. In addition, DECT post-processing techniques such as virtual monoenergetic image (VMI) reconstruction and iodine localization can increase the visibility of iodized contrast agents to improve the visualization of reduced intestinal wall enhancement [11]. Therefore, it may become increasingly valuable for the diagnosis and monitoring of bowel-related diseases. However, only a few studies have investigated the relationship between DECT and ITIN in patients with AOMI. Moreover, a comparison of the efficacy of conventional MDCT and DECT in predicting ITIN is lacking.

Patient collection

Consecutive patients with a high suspicion of AOMI were recruited at our hospital between January 2021 and January 2022. The diagnostic criteria for AOMI have been described previously [12]. Patients were required to meet the following three requirements simultaneously: (i) acute abdominal symptoms, (ii) stenosis and occlusion of the main trunk and/or branches of the SMA and/or superior mesenteric vein (SMV), and (iii) CT showing abnormal changes in the wall of the small bowel. In addition, the pathologist retrospectively reviewed the clinical excision specimens. Structural disruption of the entire small bowel wall (mucosa, submucosa, muscular, and plasma layers), as well as intestinal perforation, is considered ITIN. In addition, clinical data (including telephone interviews) 3 months after admission were reviewed. After anticoagulation or endovascular intervention, patients with AOMI who did not require surgical bowel resection and whose clinical symptoms/signs disappeared were classified as non-ITIN. Patients with AOMI who underwent conventional abdominal MDCT or plain and two-phase enhanced DECT scan were included in this study. Notably, cases were excluded for the following reasons: patients with chronic mesenteric ischemia (duration of disease > 4 weeks); CT examination of advanced AOMI patients with signs of free abdominal gas, intestinal wall gas, and mesenteric venous gas at first admission; quantitative measurement affected by the appearance of thinning of the intestinal wall on CT, stenosis, or occlusion of mesenteric vessels caused by tumor invasion or cancer-associated thrombus; intestinal wall abnormalities caused by non-mesenteric vascular obstruction; CT image artifacts affecting the quantitative and qualitative evaluation of lesions; and incomplete clinical data.

This retrospective study was approved by the ethics committee of our hospital and the requirement for informed patient consent was waived.

Image acquisition equipment and parameters

Participants were examined using 64-section and 128-section CT machines, and DECT data were acquired using the SOMATOM Force (third-generation) dual-source CT system (Siemens Healthcare, Forchheim, Germany). All patients underwent standardized imaging protocols, including plain abdominal, arterial, and portal vein-phase imaging. For DECT scanning, the plain scan adopted Care Dose 4D auto-adjustment technology with a voltage setting of 120 kVp. The specific parameters were as follows: detector collimation was 64 × 0.6 mm; spiral pitch was 0.8; rotational speed was 0.5 s/r; kernel coefficient was B25f smooth. For DECT enhancement scanning, two X-ray tubes with different voltages were used for detection based on Care Dose 4D technology: tube A voltage of 90 kVp and tube B voltage of Sn 150 kPv. The scanning parameters were as follows: collimator, 64 × 0.6 mm; field of view, 512 mm × 512 mm; pitch, 0.8; and tube rotation speed, 0.5 s/r. The arterial phase was initiated using the TEST Bolus, with the threshold for the start CT value set to 100 HU and a delay of 4 s to start the scan. Meanwhile, the intravenous phase began to be collected approximately 75 s after the injection of the contrast agent. The contrast agent was injected into the right anterior elbow of all patients using a double-barrel syringe; tube A contained uvixine (370 mgI/mL), and tube B contained normal saline (50 mL, injection rate 3.5 mL/s). In addition, the Care Dose 4D technology was employed to conduct conventional MDCT three-phase scanning with a tube voltage of 120 kVp.

Image postprocessing

Portal vein imaging

The intestinal wall abnormalities were evaluated using portal vein imaging. For conventional CT, the collected raw data were reconstructed using a convolution kernel (soft-tissue, B25f, Siemens) and iterative reconstruction technique (SAFIRE-3), and the images (layer thickness: 1.0 mm; spacing: 0.7 mm) were transferred to a post-processing workstation (Syngo MMWP VE40A). Multiplanar reconstruction (MPR) was performed according to the requirements with a thickness and spacing of 2 mm. For DECT, the double-energy raw data (90 kVp and Sn 150 kVp from the portal venous phase) were reconstructed using a convolution kernel (soft-tissue, B25f) and an iterative reconstruction technique (ADMIRE, strength level 3), and the images were then transferred to a Siemens post-processing workstation (Syngo.Via, version 30A). The low- and high-kV data were then fused via linear fusion (ratio: 6:4; fusion coefficient: M_0.6) to simulate a conventional 120 kVp mixed energy image. In addition, it has been found that the best image quality can be obtained from 50 keV [13]. Thus, we utilized a dual-energy Monoenergetic Plus (Mono +) to reconstruct 50-KeV VMI, and iodine density maps were acquired using liver nailfold video capillaroscopy (NVC) software.

Arterial phase image

The lesion area and extent of SMA were evaluated using arterial-phase images. Raw arterial phase data from the DECT scan were simulated by linear fusion to simulate conventional 120-kVp hybrid energy images [14].

Subjective image analysis

Two experienced radiologists (with 20 years of experience in abdominal CT diagnosis) independently analyzed the subjective CT signs, which mainly included the lesion area and extent of the SMA, intestinal wall, and extraintestinal CT signs at 120 kVp. SMA partitioning was applied to determine the location of SMA stenosis or occlusion. The SMA was divided into the following four regions: region I, the starting part of the SMA; region II, the main SMA trunk containing the initiation of the middle colic artery; region III, the SMA trunk below the initiation of the middle colic artery; and region IV, the branch arteries around the main SMA trunk, including the middle colic artery, jejunal artery, ileal artery, and ileocolic artery (Fig. 1). The extent of SMA lesion involvement was categorized as localized (≤ 20 mm), segmental (20 to 50 mm), and diffuse (≥ 50 mm or ≥ 2 localized and/or segmental lesions).

The subjective signs of AOMI major intestinal wall and extra-intestinal abnormalities on CT were as follows: (1) intestinal wall thickening, thickness ≥ 3 mm; (2) intestinal wall of the diseased segment was visually hyperdense; (3) intestinal wall was highly strengthened; (4) intestinal wall of the lesion was weakened; (5) dilatation of the intestinal cavity, with pipe diameter ≥ 25 mm; (6) mesenteric exudation; (7) abdominal free fluid; (8) substantial organ infarcts, mainly including liver, spleen, and kidney, were seen in cuneiform hypoperfusion area.

Objective image analysis

Objective image analysis of DECT-acquired data was conducted by two experienced radiologists, including CT values of the diseased intestinal wall (CT _{50keV lesion}) and the ratio of the normal to diseased intestinal wall (CT _{50keV normal/lesion}) measured in the venous phase for VMI at 50keV, as well as the iodine concentration (IC) in the diseased intestinal wall (IC _lesion) and the ratio of IC in the normal to disease (IC _{normal/lesion}) measured on the intravenous iodinogram. During the measurement, the image was enlarged three times, and the ROI was outlined by selecting the most obvious area of the lesion, avoiding areas with obvious small blood vessels, gas, and artifacts. Individual heterogeneity exists in the shape and size of the patient’s ROI owing to differences in intestinal wall thickness and the degree of bowel dilation. The area, selected level, and location of the ROI for each patient were maintained constant. The average of two measurements was used to minimize measurement error. If there was a dispute between different physicians regarding the identification of normal and diseased intestinal walls, a consensus was reached through negotiation.

Statistical analysis

All data analyses were conducted using SPSS software (version 26.0; IBM Corp.). The Kolmogorov–Smirnov test was used to test the normality of the data distribution. For the DECT objective indicators, normally distributed continuous variables were compared between the groups using the independent t-test, whereas non-normally distributed variables were compared using the Mann–Whitney U test. For subjective CT signs, Pearson’s chi-square test or Fisher’s exact probability method was used for comparison between groups. With the occurrence of ITIN as the dependent variable, multivariate logistic regression was used to analyze the correlation between subjective CT signs and ITIN, and the odds ratio (OR) and 95% confidence interval (CI) of each factor were calculated. The AUC of different indicators were compared using the Delong test, and this analysis was performed using MedCale 20.0. Statistical significance was set at p < 0.05.

Study population

A total of 192 patients with AOMI were consecutively collected, and the following cases that did not meet the criteria were excluded: only underwent CT plain scan (20 cases); occlusion and stenosis caused by tumor invasion of mesenteric arteries and veins (17 cases); patients with previous clinical interventions (14 cases); patients with a disease duration > 4 weeks (14 cases); CT showed signs of abdominal free gas, intestinal wall gas, and mesenteric venous gas in advanced patients (seven cases); intestinal wall pattern of patients was thin and could not be accurately measured (12 cases); image impacted assessment (three cases); and clinical data were incomplete (three cases). Ultimately, 102 patients were included in this study. Of these patients, 62 had SMAT or SAME, 29 had SMVT, 11 had both, and 48 had ITIN. The clinical characteristics of the patients are summarized in Table 1.

Table 1

Clinical characteristics of included patients
	All cohort (n = 102)	Non-ITIN (n = 54)	ITIN (n = 48)	t/χ²	P
Age (year)	70.00 ± 13.33	66.50 ± 13.72	73.94 ± 11.82	-2.914	0.004
Sex, M (%)	54 (52.9)	32 (59.3)	22 (45.8)	1.839	0.175
Complication, n (%)
Hypertension	50 (49.0)	27 (50.0)	23 (47.9)	0.044	0.834
Diabetes	16 (15.7)	9 (16.7)	7 (14.6)	0.083	0.773
Heart disease	51 (50.0)	25 (46.3)	26 (54.2)	0.630	0.427
History of cerebrovascular disease	16 (15.7)	8 (14.8)	8 (16.7)	0.066	0.797
Scanning mode, n (%)				0.123	0.725
DECT	47 (46.1)	24 (44.4)	23 (47.9)
Conventional MDCT	55 (53.9)	30 (55.6)	25 (52.1)
Vascular involvement, n (%)				3.970	0.137
SMA	62 (60.8)	33 (61.1)	29 (60.4)
SMV	29 (28.4)	18 (33.3)	11 (22.9)
SMA + SMV	11 (10.8)	3 (5.6)	8 (16.7)

DECT objective parameters analysis

Forty-seven patients with AOMI, including 23 patients with ITIN, were scanned using DECT. The CT _{50keV lesion} value in the ITIN group was significantly lower than that in the non-ITIN group (p = 0.027, Fig. 2A), whereas the CT _{50keV normal/lesion} in the ITIN group was significantly higher than that in the non-ITIN group (p = 0.003, Fig. 2B). Similar results were observed for IC-related indicators; that is, patients in the ITIN group had markedly lower IC lesion values than those in the non-ITIN group (p = 0.006, Fig. 2C), whereas patients in the ITIN group had higher IC _{normal/lesion} values than those in the non-ITIN group (p = 0.001, Fig. 2D).

CT subjective parameters analysis

Among 102 patients, the incidence of reduced or absent bowel wall enhancement (p = 0.003), bowel dilation (p < 0.001), and parenchymal organ infarction (p = 0.020) were significantly higher in the ITIN group than those in the non-ITIN group (Table 2). In addition, the occurrence of ITIN was not associated with mesenteric vessel involvement (p = 0.137). Among these participants, 62 had SMA stenosis or occlusion, and there was no significant difference between the ITIN and non-ITIN groups in terms of the extent of SMA stenosis/occlusion (p = 0.195) and the distribution area (p = 0.148).

Table 2

Comparison of CT subjective parameters between ITIN and non-ITIN groups
CT signs	Total	ITIN	Non-ITIN	χ2	P
Vascular CT sign	n = 62	n = 29	n = 33
SMA stenosis/occlusion involved range, n (%)				3.267	0.195
≤ 20 mm	8 (12.9)	2 (6.9)	6 (18.2)
20–50 mm	16 (25.8)	6 (20.7)	10 (30.3)
≥ 50 mm	38 (61.3)	21 (72.4)	17 (51.5)
SMA narrow/blocked area, n (%)				9.939	0.148
I	5 (8.1)	2 (6.9)	3 (9.1)
II	0 (0)	0 (0)	0 (0)
III	2 (3.2)	0 (0)	2 (6.1)
IV	8 (12.9)	1 (3.4)	7 (21.2)
I + II	1 (1.6)	0 (0)	1 (3.0)
III + IV	24 (38.7)	14 (48.3)	10 (30.3)
I + II + III	4 (6.5)	1 (3.4)	3 (9.1)
II + III + IV	11 (17.7)	6 (20.7)	5 (15.2)
I + II + III + IV	7 (11.3)	5 (17.2)	2 (6.1)
Intestinal wall CT sign, n (%)	n = 102	n = 48	n = 54
Bowel wall thickening	62 (60.8)	32 (66.7)	30 (55.6)	1.949	0.163
Reduced or absent bowel wall enhancement	74 (72.5)	43 (89.6)	31 (57.4)	4.543	0.033
Intestinal wall enhancement	4 (3.9)	0 (0)	4 (7.4)		0.122
Normal scan intestinal wall density	8 (7.8)	4 (8.3)	4 (7.4)	<0.001	1
Bowel dilation	47 (46.1)	34 (70.8)	13 (24.1)	24.095	<0.001
Parenteral CT sign, n (%)
Swelling and exudation in the mesentery	61 (59.8)	30 (62.5)	31 (57.4)	0.588	0.443
Seroperitoneum	47 (46.1)	24 (50.0)	23 (42.6)	0.872	0.350
Substantial organ infarction	45 (44.1)	27 (56.3)	18 (33.3)	5.413	0.020

As shown in Table 3, the binary logistic regression analysis revealed reduced or absent bowel wall enhancement (OR = 5.576, p = 0.009), bowel dilatation (OR = 11.613. p < 0.001), and parenchymatous organ infarction (OR = 4.727, p = 0.007) were independent risk factors for ITIN. The AUC of reduced or absent bowel wall enhancement, bowel lumen dilatation, and substantial organ infarction for predicting ITIN were 0.681, 0.753, and 0.615, respectively. Additionally, the AUC of the three subjective CT signs combined to predict ITIN was 0.8530. The Delong test showed that the AUC for the combined prediction of ITIN based on subjective signs was higher than that for reduced or absent intestinal wall enhancement (p < 0.0001), intestinal dilatation (p = 0.0006), and organ infarction (p < 0.0001). There was no significant difference in the AUC between reduced or absent intestinal wall enhancement, bowel dilation, and organ infarction (all p > 0.05, Table 4 and Fig. 3A).

Table 3

Binary logistic regression analysis of factor influencing ITIN in CT subjective signs
CT signs	B value	Wald value	OR ^a	95%CI	P
Reduced or absent bowel wall enhancement	1.718	6.903	5.576	(1.547, 20.093)	0.009
Bowel dilation	2.452	18.420	11.613	(3.790, 35.586)	<0.001
Parenchymatous organ infarction	1.553	7.332	4.727	(1.536, 14.551)	0.007

Table 4

Efficacy of CT subjective signs to predict ITIN
CT signs	AUC (95%CI)	P	Sensitivity (95%CI)	Specificity (95%CI)
Reduced or absent bowel wall enhancement	0.681(0.581, 0.769)^a	0.002	91.67(80.0, 97.7)	44.44(30.9, 58.6)
Bowel dilation	0.753(0.658, 0.833)^a	< 0.001	72.92(58.2, 84.7)	77.78(64.4, 88.0)
Parenchymatous organ infarction	0.615(0.513, 0.709)^a	0.046	56.26(41.2, 70.5)	66.67(52.5, 78.9)
Combination signs	0.853(0.769, 0.915)^b	< 0.001	93.75(82.8, 98.7)	64.81(50.6, 77.3)

Comparison of DECT objective indicators and CT subjective signs in predicting ITIN

In the 47 patients detected by DECT, the AUC for predicting ITIN was 0.794 with a CT cutoff value of CT _{50keV normal/lesion} = 2.81, while its AUC was 0.777 with a CT cutoff value of IC _{normal/lesion} = 2.39. In these patients, the AUC for the combined CT signs was 0.801. The Delong test showed no significant difference in the AUC for predicting ITIN between the DECT objective indicators (CT _{50keV normal/lesion}, IC _{normal/lesion}) and CT combined subjective signs (p > 0.05). Thus, we replaced some subjective signs with objective indicators. When CT _{50keV normal/lesion} and IC _{normal/lesion} were used instead of reduced and absent intestinal wall reinforcement in the subjective sign combination, the predicted ITIN AUC were 0.857 and 0.896, respectively. Among them, there was a difference in the AUC between IC normal/lesions combined with intestinal lumen dilatation and parenchymal organ infarction combined with subjective CT signs (Table 5 and Fig. 3B). Furthermore, there were no significant differences among the other groups. Figure 4–6 exhibit representative DECT images of three cases: two with ITIN and one without.

Table 5

Comparison of the efficacy of DECT objective indicators and CT subjective signs in predicting ITIN
CT parameters	AUC (95%CI)	P	Sensitivity (95%CI)	Specificity (95%CI)
CT _{50KeV normal/lesion}	0.794 (0.615, 0.916)^a	0.005	56.52 (34.5, 76.8)	87.50 (67.6, 97.3)
IC _{normal/lesion}	0.777 (0.596, 0.904)^a	0.001	73.91 (51.6, 89.8)	79.17 (57.8, 92.9)
Combined subjective signs	0.801 (0.622, 0.920)^a	0.006	80.95 (58.1, 94.6)	72.73 (39.0, 94.0)
CT_{50KeVnormal/lesion} combined with intestinal dilatation and parenchymatous organ infarction	0.857 (0.688, 0.955)^ab	0.001	95.65 (78.1, 99.9)	79.17 (57.8, 92.9)
IC_{normal/lesion} combined with intestinal dilatation and parenchymatous organ infarction	0.896 (0.737, 0.976)^b	< 0.001	100 (85.2, 100)	70.83 (49.8–87.4)

AMI is a rare and often misdiagnosed disease that is usually diagnosed late and has a high mortality rate [15]. Therefore, the diagnosis and treatment of patients with suspected AMI, particularly those at risk for ITIN, should be highly valued. Unfortunately, the lack of specific clinical symptoms and experimental parameters often lead to significant delays in diagnosis and targeted therapy. In this study, we aimed to evaluate the potential of DECT in predicting the occurrence of ITIN in AOMI. We also observed the significance of a combination of CT subjective signs and objective DECT indicators in the diagnosis of ITIN.

In the assessment of subjective CT imaging parameters, we found that reduced or absent bowel wall enhancement, bowel dilation, and parenchymatous organ infarction were independent risk factors for ITIN. Notably, the combination of the three CT parameters had favorable performance in predicting ITIN, with an AUC of 0.8530 (sensitivity: 93.75%), which was higher than that of a single indicator. Hypoenhancement of the bowel wall is essential for the early detection of AMI [12]. Abdominal CT showing reduced or absent bowel wall enhancement is a specific but insensitive finding that indicates reduced or absent arterial blood flow. Previous studies have revealed that this parameter is correlated with transmural necrosis of the small intestinal wall, particularly in cases of intravenous AMI. In the early stages of AOMI, the regional arterial blood flow is below a critical threshold, suggesting that the bowel wall is still alive and the damage is reversible [16]. Reduced local arterial inflow occurs only in the late stages of occlusive AMI, and enhanced CT exhibits decreased or no enhancement, indicating possible irreversible damage to the intestinal wall [17]. The evidence suggests that bowel dilation is more common in patients with arterial AOMI [18]. This shows that disruption of intestinal peristalsis is a reflection of ischemic injury and causes irreversible whole-wall ischemic damage to the intestinal wall. Hence, the rate of surgical resection increases when dilatation is present [19]. Consistent with these studies, we found that patients in the ITIN group were more likely to have intestinal dilatation (71%, 34/48). Parenchymatous organ infarction is common in patients with embolic AMI, and its presence as an auxiliary finding is highly specific [20]. In this study, the incidence of parenchymatous organ infarction was 56% (27/48) in the ITIN group. After organ infarction, it causes abnormal biochemical parameters such as blood creatinine and bilirubin, which may lead to organ failure [21]. Organ failure is an independent risk factor for ITIN and may be associated with high mortality rates. Taken together, it is necessary to have a higher degree of suspicion and familiarity with the CT spectral manifestations of AOMI, which can assist in the accurate diagnosis of ITIN and determination of the therapeutic strategy.

Although CT signs have a good predictive value, they mainly rely on the subjective evaluation of observers, especially reduced or absent bowel wall enhancement. Furthermore, the specificity of three combined CT signs for predicting ITIN was unsatisfactory (64.81). Therefore, we analyzed the DECT results. In this study, we quantified the degree of intestinal wall ischemia in patients using iodine concentration measurement (IC) and attenuation measurement (VMI, CT50keV) and then evaluated the predictive performance of DECT objective parameters on TINI. There was no significant difference in the predictive abilities of DECT and CT signs for ITIN. Next, to reduce the subjective heterogeneity, we used quantitative measures in DECT to replace some subjective CT signs. The results demonstrated that replacing reduced or absent bowel wall enhancement in the combination model with IC normal/lesions enhanced the predictive efficacy of ITIN (from 0.853 to 0.896), and sensitivity (100%) and specificity (70.83%). In recent years, DECT has emerged as a diagnostic technology for the clinical detection of various diseases [22]. IC is the most commonly used quantitative parameter in DECT and is considered equivalent to the actual enhancement value. In the bowel, Lourenco et al. found that iodine mapping and 40-keV reconstruction techniques reduced the subjectivity and difficulty of wall enhancement and provided the greatest visual difference between non-ischemic and ischemic bowel segments, allowing early and accurate detection of intestinal ischemia [23]. Mazzei et al. also found that DECT with iodograms and low-energy images helped assess intestinal wall vascularization more accurately [24]. Consistent with these studies, we also found that iodograms and low-energy images (50 keV) provided superior image quality for the effective assessment of intestinal wall lesions and the accuracy of ITIN diagnosis. In routine diagnosis, physicians can directly calculate CT 50keV _{normal/lesion} and IC _{normal/lesion} values to initially assess whether ITIN occurs in patients with AMI. These quantitative parameters are more accurate and reliable than the subjective CT signs alone.

This is the first study to confirm the application of DECT in the evaluation of ITIN. This study had three major limitations. First, the number of patients who underwent DECT was small. This is mainly due to the lack of typical clinical manifestations in patients with early-stage AOMI. Second, there are differences in MDCT signs between arterial and venous AMI. Due to the limited sample size, the etiology of AOMI has not yet been classified in detail. Finally, the defined thresholds, particularly those calculated from IC, depended on the CT protocol used. There is evidence that the type (amount) of contrast agent, method of administration, and imaging delay have an impact on the measured IC [25]. Hence, the findings of this study need to be verified in a larger sample population.

In summary, subjective CT signs and objective DECT parameters provide good performance in predicting the occurrence of ITIN in patients with AOMI. Intravenous-phase CT _{50 keV normal/lesion} and IC _{normal/lesion} were effective objective parameters for predicting ITIN, of which IC _{normal/lesion} combined with subjective CT signs (intestinal dilatation and organ infarction) had the best predictive efficacy. The accurate identification of intestinal ischemia and necrosis is of great clinical significance for the development of therapeutic regimens and for improving the prognosis of patients with AOMI.

Author contributions: Ju-shun Yang, Bo-sheng He were responsible for design of the study and reviewed the manuscript. Ju-shun Yang drafted the manuscript. Zhen-yu Xu, Fei-xiang Chen and Mei-rong Wang performed data collection and analysis. Ju-shun Yang and Xiao-le Fan prepared the figures and tables. Bo-sheng He were responsible for revising manuscript. All authors have read and approved the final manuscript.

Acknowledgments: This work was Supported by The Project of Nantong City Health Committee, No. MS20230276; The "333" Talent Funding Project of Jiangsu Province, No. BRA2020198; The Project of Jiangsu Provincial Health Commission, No. ZD2021059; and The Youth Research Fund of Nantong Municipal Health Commission, No. QNZ2023027.

Ethical approval

This study was a retrospective, observational, and single-center study. The study was approved by the ethics committee of Affiliated Hospital 2 of Nantong University (No. 2021KT154). Since this was a retrospective study, informed consent was waived.

Conflict of interest

No financial or nonfinancial benefits have been received or will be received from any party related directly or indirectly to the subject of this article.

Data Availability Statement

All data generated or analyzed during this study were available from the corresponding author Bosheng He upon reasonable request.

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No competing interests reported.

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Diagnostic value of dual-energy CT in detecting irreversible transmural intestinal necrosis in patients with acute occlusive mesenteric ischemia

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Abstract

Background

Methods

Results

Conclusion

Figures

INTRODUCTION

METHODS

Patient collection

Image acquisition equipment and parameters

Image postprocessing

Portal vein imaging

Arterial phase image

Subjective image analysis

Objective image analysis

Statistical analysis

RESULTS

Study population

DECT objective parameters analysis

CT subjective parameters analysis

Comparison of DECT objective indicators and CT subjective signs in predicting ITIN

DISCUSSION

CONCLUSION

Declarations

References

Additional Declarations

Status:

Version 1