Application of DynaCT biliary soft tissue reconstruction technology in diagnosis and treatment of hepatolithiasis

Abstract

BACKGROUND

Hepatobiliary stone disease involves an intrahepatic bile duct stone that occurs above the confluence of the right and left hepatic ducts. One-step percutaneous transhepatic cholangioscopic lithotripsy (PTCSL) using the percutaneous transhepatic one-step biliary fistulation (PTOBF) technique enables the clearing of intrahepatic stones and the resolution of strictures. However, hepatolithiasis with associated strictures still has high residual and recurrence rates after one-step PTCSL. DynaCT can achieve synchronized acquisition with a flat-panel detector during C-arm rotation. The technical approach and application value of DynaCT biliary soft tissue reconstruction technology for the diagnosis and treatment of hepatolithiasis with bile duct stenosis were evaluated in this study.

AIM

To explore the value of DynaCT biliary soft tissue reconstruction technology for the diagnosis and treatment of hepatolithiasis with bile duct stenosis, and to assess the feasibility and effectiveness of the PTOBF technique guided by DynaCT biliary soft tissue reconstruction technology.

METHODS

The clinical data of 140 patients with complex biliary stenosis disease combined with bile duct stenosis who received PTOBF and were admitted to the First Affiliated Hospital of Guangzhou Medical University from January 2020 to December 2024 were collected. The patients were divided into two groups: DynaCT-PTOBF group (70 patients) and conventional PTOBF group (70 patients). These groups were compared in terms of the preoperative bile duct stenosis, location of the liver segment where the stone was located, intraoperative operative time, immediate stone retrieval rate, successful stenosis dilatation rate, postoperative complication rate, postoperative reoperation rate, stone recurrence rate, and stenosis recurrence rate.

RESULTS

DynaCT biliary soft tissue reconstruction technology was successfully performed in 70 patients. The DynaCT-PTOBF group had a higher detection rate of target bile ducts where bile duct stones and biliary strictures were located than the PTOBF group. Compared with the PTOBF group, the DynaCT-PTOBF group was characterized by a significantly greater immediate stone removal rate (68.6% vs 50.0%, P = 0.025), greater immediate stenosis dilatation success rate (72.9% vs 55.7%, P = 0.034), greater final stenosis release rate (91.4% vs 75.7%, P = 0.012), shorter duration of intraoperative hemorrhage (3.14 ± 2.00 vs 26.5 ± 52.1, P = 0.039), and lower incidence of distant cholangitis (2.9% vs 11.4%, P = 0.49). There were no significant differences between the two groups in terms of the final stone removal rate, reoperation rate, or long-term complication incidence rate.

CONCLUSION

DynaCT biliary soft tissue reconstruction technology guiding the PTOBF technique in patients with hepatolithiasis with bile duct stenosis is feasible and accurate. It may be beneficial for optimizing the preoperative evaluation of the PTOBF technique.

Key Words: Hepatolithiasis; Biliary stenosis; DynaCT; One-step percutaneous transhepatic cholangioscopic lithotripsy

Core Tip: DynaCT was used for the first time in patients with hepatolithiasis with biliary stenosis. Compared with computed tomography, DynaCT for biliary reconstruction results in higher-quality, three-dimensional biliary, blood vessel, and liver images. Based on DynaCT biliary model, one-step percutaneous transhepatic cholangioscopic lithotripsy has the potential to improve the stone clearance rate, shorten the stone clearance time, and reduce the reoperation rate.

INTRODUCTION

Hepatobiliary stone disease involves an intrahepatic bile duct stone that occurs above the confluence of the right and left hepatic ducts. It is a common benign biliary disease in hepatobiliary surgery and is the main cause of death from nonneoplastic biliary diseases. It is highly prevalent in the Southwest, East Coast, Hong Kong, and Taiwan in China, with a prevalence of up to 6.1%[1,2]. An average of 24.3% of patients with hepatic bile duct stone disease have hepatic bile duct stenosis[3,4]. One-step percutaneous transhepatic cholangioscopic lithotripsy (PTCSL) using the percutaneous transhepatic one-step biliary fistulation (PTOBF) technique enables the clearing of intrahepatic stones and the resolution of strictures. However, hepatolithiasis with associated strictures still has high residual and recurrence rates after one-step PTCSL.

Ultrasound is the preferred method for treating hepatolithiasis[5]; however, it is not effective in providing an overall picture of the biliary tree. Enhanced abdominal computed tomography (CT) has excellent resolution in the bile duct, hepatic arteries, and portal veins. Moreover, it can display high-density stones clearly, but this technology is not effective for showing structures such as negative calculi, small sediment-like stones, and bile duct strictures[6,7]. Magnetic resonance cholangiopancreatography (MRCP) is the most sensitive noninvasive method for visualizing the biliary tree and bile duct calculi[8,9]. However, it has several limitations. For example, previous studies have shown that its sensitivity in the diagnosis of small stones (≤ 3 mm) is only 64%[10]. Koshinaga et al[11] missed calculi in 29% of patients with small stones (3-5 mm). Moreover, MRCP cannot visualize the biliary tree in the presence of abnormal biliary pathology. In addition, blood, proteinaceous material, or air in the bile duct can mimic a stone, and sludge can simulate a stenosis[12]. T-tube cholangiography can show subtle lesions in the bile ducts clearly and detect small stones, but it provides two-dimensional images that are poor at visualizing bile duct stones and their adjacent spatial structures[13]. The lack of accurate imaging tools to guide percutaneous transhepatic cholangioscopic lithotripsy procedures is a majorly influential factor.

To address these challenges, our center introduced an innovative approach involving the use of DynaCT for biliary reconstruction and the successful use of DynaCT biliary soft tissue reconstruction technology images for the preoperative assessment and treatment of hepatolithiasis[14]. DynaCT is a type of cone beam CT (CBCT) attached to the Artis Zee DSA system produced by the SIEMENS Company in Germany, which can realize synchronized acquisition with a flat-panel detector during C-arm rotation[15]. This application of DynaCT biliary soft tissue reconstruction technology enables us to obtain optimal images of the bile duct and stones. First, DynaCT biliary soft tissue reconstruction technology has the ability to enhance three-dimensional (3D) and anatomy-assisted visualizations of the bile duct, which can increase the knowledge of the biliary anatomy, morphology, size, and distribution of the calculus. Second, it can generate more accurate structures of the vascular, liver, and biliary systems, which allows the surgeon to plan the surgery accordingly and tailor the procedure for each individual patient.

The aim of this study was to evaluate the effectiveness and clinical value of DynaCT biliary soft tissue reconstruction technology in the diagnosis and treatment of hepatolithiasis with bile duct stenosis.

MATERIALS AND METHODS

Data source

At our institution, all patients with suspected hepatolithiasis undergo a standardized diagnostic work-up according to the current guidelines, and patients with a confirmed diagnosis of hepatolithiasis are treated by one-step PTCSL. This retrospective study included 140 patients with hepatolithiasis from January 2020 to December 2024. Among these patients, those undergoing PTOBF served as the control group, which included 70 patients whose procedures were guided by ultrasound. Their relevant surgical index data were recorded. Patients undergoing DynaCT-PTOBF served as the experimental group, which also included 70 patients. Intrahepatic stones were observed, and their locations were recorded by DynaCT biliary soft tissue reconstruction technology, which guided one-step PTCSL. Similarly to the PTOBF group, their relevant surgical index data were recorded. All procedures were completed successfully without complications, such as biliary leakage, biliary bleeding, or death.

Inclusion criteria

Patients were included if they: (1) Were in a state with a biliary drain; (2) Had confirmed hepatic bile duct stones and needed to receive PTOBF; and (3) Were able to hold their breath for more than 6 s.

Exclusion criteria

Patients were excluded if they: (1) Had a history of liver transplant; (2) Had poor basal vital signs or were unable to hold their breath for more than 6 s; (3) Had an allergy to iodine contrast agents; or (4) Had a mental disorder or coagulation disorder.

DynaCT-PTOBF procedure

The DynaCT-PTOBF procedure consisted of: (1) DynaCT biliary soft tissue reconstruction: A C-arm CT machine was used to scan each patient, who was instructed to hold their breath for more than 6 s while laying flat. The digital subtraction angiography system used was the SIEMENS Artis Zee III ceiling, and the scanning sequence was the 6 s DCT Body. High-pressure syringes were used to manually inject a contrast agent (Visipaque^®, 320 mg/mL, GE Healthcare, 2:3 ratio with saline) at a flow rate of 1 to 2 mL/s. The scanning time was 6 s, and the pressure limit was 100 psi. Finally, the 3D biliary system was reconstructed via multiplanar reconstruction (MPR) and volumetric reconstruction (VR) software systems (Figures 1 and 2); and (2) DynaCT-guided PTOBF: Based on a DynaCT biliary reconstruction model, ultrasound and other imaging examinations were used to determine the location and degree of the target bile duct stenosis and stones. Biliary puncture was performed with an 18-G needle and a 0.035-inch hydrophilic guidewire. Fistula dilation was completed via fascial dilators from 8 Fr to 14 Fr sequentially. Sheath insertion was done with a 14-Fr sheath. Fragmentation and clearance were performed with a 12-Fr rigid nephroscope. A 14-Fr drainage tube was employed (Figure 3).

Figure 1  Process of DynaCT biliary soft tissue reconstruction technology.

Figure 2 Three-dimensional model combined with real-time B-ultrasonic navigation. A: Combination of three-dimensional reconstruction and B-ultrasound for guiding one-step percutaneous transhepatic cholangioscopic lithotripsy (PTCSL); B: Using the percutaneous transhepatic one-step biliary fistulation technique for one-step PTCSL.

Figure 3  DynaCT soft tissue reconstruction of the biliary tract.

Statistical analysis

SPSS 21.0 software was used to process the data, and data that conformed to a normal distribution are expressed as the mean ± SD; those that did not conform to a normal distribution are expressed as medians and interquartile ranges (25^th and 75^th percentiles), and categorical data are expressed as cases. Each parameter in the two study groups was compared via the t-test or the Wilcoxon rank-sum test. A P value < 0.05 was considered statistically significant.

RESULTS

DynaCT images of hepatobiliary stenosis and stones

DynaCT allows a wider scanning area in a shorter period of time and generates higher-quality images of the biliary tract. The common hepatic duct, the right and left hepatic ducts, and the lobular bile ducts are easily visualized, and the terminal branching bile ducts can even be reconstructed. The width of the bile duct at the stenosis and the diameter of the dilatation before and after the stenosis can be measured accurately with DynaCT's VR and MPR software systems, endoscopic simulation, and other functions (Figures 4 and 5).

Figure 4 DynaCT-guided surgical procedure. A: The digital reconstruction model of DynaCT three-dimensional (3D) reconstruction can realistically reproduce the sub-segments of the bile duct by measurements and 3D visualisation of the rotation, depicting the location and extent of the stricture; B: T-tube angiography image of the same patient with visible contrast agent; C: DynaCT soft tissue reconstruction image of the biliary tract and intraoperative ultrasound-guided biliary puncture; D: Biliary puncture; E: Biliary puncture with 18G needle and 0.035 inch hydrophilic guidewire; F: Fistula dilation with fascial dilators from 8 Fr to 14 Fr sequentially; G: Stone fragmentation and clearance with A 12 Fr rigid nephroscope; H: Choledochoscopic removal of stones.

Figure 5  Digital DynaCT biliary soft tissue reconstruction of biliary branches, biliary strictures, and stones.

Baseline characteristics of patients

From January 2020 to December 2024, 140 patients were eligible for and included in the study. Seventy of them underwent DynaCT-PTOBF, whereas the remaining 70 underwent PTOBF. There were no significant differences between the two groups with respect to demographic characteristics, including age or sex. The DynaCT-PTOBF group had a higher detection rate of target bile ducts where bile duct stones and biliary strictures were located than the PTOBF group (Table 1).

Table 1 Comparison of basic preoperative clinical data and detection of bile duct stones and strictures between the two groups.

Variable	DynaCT-PTOBF (n = 70)	PTOBF (n = 70)	P value
Age (years)	52.67 ± 14.35	50.5 ± 17.3	0.423
Sex, n (%)			0.716
Male	31	24
Female	39	46
TBIL (mmol/L)	28.39 ± 27.91	33.9 ± 32.9	0.291
DBIL (mmol/L)	13.3 ± 18.1	13.3 ± 18.1	0.366
ALT (U/L)	42.42 ± 49.30	59.9 ± 61.7	0.227
Γ-GGT (U/L)	139.97 ± 165.23	210.6 ± 262.2	0.059
ALB (G/L)	35.47 ± 4.08	39.3 ± 6.4	0.052
PT (S)	13.82 ± 1.13	14.2 ± 4.5	0.486
Child-Pugh score, n (%)			0.116
Grade A	62 (88.6)	67 (95.7)
Grade B	8 (11.4)	3 (4.3)
Location of stone, n (%)
S1	6 (8.6)	1 (1.4)	0.053
S2	12 (17.14)	9 (12.9)	0.478
S3	14 (20.0)	11 (15.7)	0.508
S4	15 (21.4)	17 (24.3)	0.687
S5	15 (21.4)	4 (5.7)	0.007
S6	13 (18.6)	12 (17.1)	0.825
S7	11 (15.7)	8 (11.4)	0.459
S8	10 (14.3)	12 (17.1)	0.642
Common bile duct, n (%)	21 (30.0)	23 (32.9)	0.716
Location of bile duct stenosis, n (%)
S1	2 (2.86)	0	0.154
S2	14 (20.0)	1 (1.4)	0.000
S3	13 (18.6)	8 (11.4)	0.237
S4	11 (15.7)	14 (20.0)	0.508
S5	16 (22.9)	4 (5.7)	0.004
S6	12 (17.1)	11 (15.7)	0.820
S7	12 (17.1)	6 (8.6)	0.130
S8	6 (8.6)	7 (10.0)	0.771
Biliary-intestinal anastomotic stenosis, n (%)	15 (21.4)	12 (17.1)	0.520
Common bile duct, n (%)	13 (18.6)	25 (35.7)	0.023

TBIL: Total bilirubin; DBIL: Direct bilirubin; ALT: Alanine aminotransferase; γ-GGT: γ-glutamyl transpeptidase; ALB: Albumin; PT: Prothrombin time; PTOBF: Percutaneous transhepatic one-step biliary fistulation.

DynaCT improves efficiency of stone clearance

Compared with the PTOBF group, the DynaCT-CT fusion group was characterized by the following significant observations: A greater rate of immediate stone removal (68.6% vs 50.0%, P = 0.025), greater immediate stenosis dilatation success rate (72.9% vs 55.7%, P = 0.034), greater final stenosis release rate (91.4% vs 75.7%, P = 0.012), shorter duration of intraoperative hemorrhage (3.14 ± 2.00 vs 26.5 ± 52.1, P = 0.039), and lower incidence of distant cholangitis ( 2.9% vs 11.4%, P = 0.49). The mean follow-up duration was 339.5 ± 316.2 d. There was no significant difference between the two groups in the final stone removal rate, reoperation rate, or incidence of long-term complications (P > 0.05) (Table 2).

Table 2 Comparison of intraoperative, postoperative, and long-term follow-up results between the two groups, n (%).

Variable	DynaCT-PTOBF (n = 70)	PTOBF (n = 70)	P value
Total surgical time (min)	55.8 ± 24.0	55.2 ± 34.0	0.900
Intraoperative haemorrhage (mL)	3.14 ± 2.00	26.5 ± 52.1	0.039
Immediate stone removal rate	48 (68.6)	35 (50.0)	0.025
Immediate stenosis dilatation success rate	51 (72.9)	39 (55.7)	0.034
Short-term complications	11 (12.9)	6 (8.6)	0.196
Haemorrhage	2 (2.9)	1 (1.4)	0.559
Pulmonary infection	1 (1.4)	2 (2.9)	0.559
Cholangitis	6 (5.7)	2 (2.9)	0.145
Pleural effusion	2 (2.9)	1 (1.4)	0.559
Follow-up time (d)	209.2 ± 20.7	498.0 ± 373.5	0.000
Final stone extraction rate	60 (85.7)	54 (77.1)	0.192
Final stenosis release rate	64 (91.4)	53 (75.7)	0.012
Number of operations	3.0 ± 1.4	3.1 ± 1.5	0.056
Stone recurrence rate	3 (4.3)	11 (15.7)	0.024
Reoperation rate	2 (2.9)	7 (10.0)	0.085
Long-term complications	3 (4.3)	9 (12.9)	0.070
Distant cholangitis	2 (2.9)	8 (11.4)	0.049
Liver failure	1 (1.4)	1 (1.4)	1.00

PTOBF: Percutaneous transhepatic one-step biliary fistulation.

DISCUSSION

Concept of DynaCT

DynaCT is a type of CBCT attached to the Artis Zee DSA system produced by SIEMENS Company in Germany and has been widely applied in the diagnosis and treatment of different diseases, such as vascular, cardiothoracic, and neurosurgical conditions[16,17]. However, its application in hepatobiliary surgery is rare. Wallace et al[18] reported that CBCT can provide images of accurate biliary anatomy and calculate the volume of the liver, especially in complex states. Raj et al[19] reported that, compared with conventional 2D cholangiography, CBCT assists in the 3D reconstruction of cholangiography images with high spatial resolution. In this study, we applied a newly developed DynaCT technology for the diagnosis and treatment of hepatolithiasis. This technique can show the distal end of the bile duct, biliary stenosis, and stones clearly, which allows the acquisition of biliary information from any angle. The utility of MPR or VR in DynaCT is that it displays complex and abnormal anatomic structures, such as multiple intrahepatic biliary strictures after liver transplantation and primary sclerosing cholangitis.

Advantages of DynaCT

The DynaCT biliary soft tissue reconstruction model can guide precise surgical punctures. During one-step PTCSL procedures, surgeons pinpoint the locations of the calculi intraoperatively, puncture the target bile ducts, and remove the stones via real-time ultrasound combined with preoperative CT or magnetic resonance[20]. Traditional two-dimensional images are sometimes difficult to identify stones from multiple angles, especially when the bile ducts have numerous bifurcation openings with distortion, irregularity, and stenosis. The use of C-arm rotational acquisition bile duct reconstruction technology can help surgeons to obtain the 3D spatial structure of the bile duct more effectively[21]. Kapoor et al[22] reported that CBCT combined with previous CT images clearly visualize the stenotic bile ducts, assisting surgeons in planning bile-intestinal anastomosis pathways.

DynaCT-guided PTOBF procedure

To obtain information on the patency of the bile ducts and the location of biliary strictures, DynaCT cholangiography can also be performed in the hybrid operating room. Surgeons can employ a rigid choledochoscope to treat the stenosed bile duct and leave an 18-F drainage tube in the distal end of the stenosed bile ducts for 6-9 mo[23,24]. In this study, the DynaCT-CT group was characterized by several significant observations. Direct biliary imaging via DynaCT revealed more stones in hepatic segments III (grade 3) and even IV (grade 4) and negative stones. The immediate stone removal, immediate stenosis dilatation success, and final stenosis release rates in the DynaCT-PTOBF group were significantly greater than those in the PTOBF group (P < 0.05). Having accurate information about the location and size of hepatobiliary stenoses and stones may help surgeons to resolve strictures more quickly, which may further reduce the stone recurrence and reoperation rates.

Limitations

There were several limitations in this study. It was a single-center study including a limited number of patients; hence, there was some inevitable selection bias between the groups that may have impacted the results.

CONCLUSION

In conclusion, this study showed that the application of DynaCT biliary soft tissue reconstruction technology can further optimize the diagnosis of hepatobiliary stones and strictures. This technology has shown unique advantages in one-step PTCSL, including a greater immediate stone removal rate, greater immediate stenosis dilatation success rate, greater final stenosis release rate, shorter duration of intraoperative hemorrhage, and lower incidence of distant cholangitis. These findings suggest that DynaCT-CT fusion can be an ideal option to guide one-step PTCSL for patients who are intolerant to conventional surgery or who have postoperative remnant calculi.