Development and validation of a comprehensive model to predict complications after hepatectomy.

OBJECTIVE: Despite advances in perioperative care, hepatectomy remains associated with morbidity rates of up to 40%. Currently, available nomograms for predicting severe post-hepatectomy complications do not include early postoperative data. This retrospective observational study aimed to determine whether the parameters routinely measured in patients admitted to the Intensive Care Unit (ICU) after hepatectomy could represent risk factors for severe morbidity and to propose a nomogram scoring system to predict severe postoperative complications. PATIENTS AND METHODS: 411 adult patients who underwent elective hepatectomy at a high-volume tertiary care center for hepatic surgery from December 2016 to June 2022 were enrolled. The primary outcome was the assessment of predictors of 30-day severe postoperative complications following hepatectomy, defined as Clavien-Dindo grade 3a or higher. As a secondary outcome, we aimed to develop an easy-to-use scoring system to estimate the risk of severe postoperative complications. RESULTS: Severe complications occurred in 78 patients (19%). The final model included body mass index, preoperative bilirubin level, and ICU data (i.e., pH, lactate clearance, arterial lactate concentration 12 hours after ICU admission, need for packed red blood cell transfusions, and length of stay). Notably, the latter three variables were proven to be independent predictors of the outcomes. The model showed an overall good fit (C-index=0.754, corrected Dxy=0.692). A calibration plot using bootstrap internal validity resampling confirmed the stability of the model (mean absolute error=0.017, root mean square error of approximation=0.00051). CONCLUSIONS: We developed an accurate and practical scoring system based on preoperative and early postoperative data to predict poor outcomes after hepatectomy. Further external validation on larger series could lead to the integration of such a tool in the routine clinical practice to support patients' management and early warning during ICU stay. Graphical Abstract: https://www.europeanreview.org/wp/wp-content/uploads/Graphical-Abstract-NEW-2.pdf.

Percutaneous biliary stent removal for benign biliary stricture post hepaticojejunostomy.

This case report presents the percutaneous extraction of a biliary stent in a patient with a history of liver transplant and Whipple procedure, suffering from benign biliary stricture post hepaticojejunostomy. After failed management with conventional benign biliary protocol, a fully covered WallFlex biliary stent was percutaneously placed and later removed using a balloon catheter technique. The procedure demonstrated anastomosis patency without complications, providing a drain-free option for complex anatomy where endoscopic management was not feasible. This case contributes valuable insights to the limited literature on percutaneous stent removal for benign biliary strictures, emphasising the importance of considering alternative approaches in challenging clinical scenarios.

'Burn and Push' technique: A novel robotic liver parenchymal transection technique.

BACKGROUND: Liver parenchymal transection during robotic liver resection (RLR) remains a significant challenge due to the limited range of specialised instruments. This study introduces our 'Burn and Push' technique as a novel approach to address these challenges. METHODS: A retrospective analysis was conducted on 20 patients who underwent RLR using the 'Burn and Push' technique at Virginia Commonwealth University Health System from November 2021 to August 2023. The study evaluated peri- and post-operative outcomes. RESULTS: The median operation time was 241.5 min (range, 90-620 min), and the median blood loss was 100 mL (range, 10-600 mL). Major complications occurred in one case, with no instances of postoperative bleeding, bile leak, or liver failure. CONCLUSIONS: The 'Burn and Push' technique is a viable and efficient alternative for liver parenchymal transection in RLR. Further research with larger sample sizes and consideration of the learning curve is necessary to validate these findings.

Advances in Tumor Management: Harnessing the Potential of Histotripsy.

Tissue ablation techniques have long been used in clinical settings to treat various oncologic diseases. However, many of these techniques are invasive and can cause substantial adverse effects. Histotripsy is a noninvasive, nonionizing, nonthermal tissue ablation technique that has the potential to replace surgical interventions in various clinical settings. Histotripsy works by delivering high-intensity focused ultrasound waves to target tissue. These waves create cavitation bubbles within tissues that rapidly expand and collapse, thereby mechanically fractionating the tissue into acellular debris that is subsequently absorbed by the body's immune system. Preclinical and clinical studies have demonstrated the efficacy of histotripsy in treating a range of diseases, including liver, pancreatic, renal, and prostate tumors. Safety outcomes of histotripsy have been generally favorable, with minimal adverse effects reported. However, further studies are needed to optimize the technique and understand its long-term effects. This review aims to discuss the importance of histotripsy as a noninvasive tissue ablation technique, the preclinical and clinical literature on histotripsy and its safety, and the potential applications of histotripsy in clinical practice. Keywords: Tumor Microenvironment, Ultrasound-High-Intensity Focused (HIFU), Ablation Techniques, Abdomen/GI, Genital/Reproductive, Nonthermal Tissue Ablation, Histotripsy, Clinical Trials, Preclinical Applications, Focused Ultrasound © RSNA, 2024.

Management of complex pediatric and adolescent liver trauma: adult vs pediatric level 1 trauma centers.

PURPOSE: Management of high-grade pediatric and adolescent liver trauma can be complex. Studies suggest that variation exists at adult (ATC) vs pediatric trauma centers (PTC); however, there is limited granular comparative data. We sought to describe and compare the management and outcomes of complex pediatric and adolescent liver trauma between a level 1 ATC and two PTCs in a large metropolitan city. METHODS: A retrospective review of pediatric and adolescent (age < 21 years) patients with American Association for the Surgery of Trauma (AAST) Grade 4 and 5 liver injuries managed at an ATC and PTCs between 2016 and 2022 was performed. Demographic, clinical, and outcome data were obtained at the ATC and PTCs. Primary outcomes included rates of operative management and use of interventional radiology (IR). Secondary outcomes included packed red blood cell (pRBC) utilization, intensive care unit (ICU) length of stay (LOS), and hospital LOS. RESULTS: One hundred forty-four patients were identified, seventy-five at the ATC and sixty-nine at the PTC. The cohort was predominantly black (65.5%) males (63.5%). Six injuries (8.7%) at the PTC and forty-five (60%) injuries at the ATC were penetrating trauma. Comparing only blunt trauma, ATC patients had higher Injury Severity Score (median 37 vs 26) and ages (20 years vs 9 years). ATC patients were more likely to undergo operative management (26.7% vs 11.0%, p = 0.016) and utilized IR more (51.9% vs 4.8%, p < 0.001) compared to the PTC. The patients managed at the ATC required higher rates of pRBC transfusions though not statistically significant (p = 0.06). There were no differences in mortality, ICU, or hospital LOS. CONCLUSION: Our retrospective review of high-grade pediatric and adolescent liver trauma demonstrated higher rates of IR and operating room use at the ATC compared to the PTC in the setting of higher Injury Severity Score and age. While the PTC successfully managed > 95% of Grade 4/5 liver injuries non-operatively, prospective data are needed to determine the optimal algorithm for management in the older adolescent population. LEVEL OF EVIDENCE: Level IV.

Liver regeneration of living donor after liver donation for transplantation: Disparity in the left and right remnant liver.

Donor safety is crucial for living donor liver transplantation (LDLT), and sufficient liver regeneration significantly affects outcomes of living donors. This study aimed to investigate clinical factors associated with liver regeneration in living donors. The study retrospectively reviewed 380 living donors who underwent liver donation at Chang Gung Memorial Hospital in Linkou. The clinical characteristics and medical parameters of donors were analyzed and compared according to liver donation graft type. There were 355 donors (93.4%) with right hemi-liver donations and 25 donors (6.6%) with left hemi-liver donations. Left hemi-liver donors had a higher body mass index (BMI) and a larger ratio of remnant liver volume (RLV) to total liver volume (TLV). However, the 2 groups showed no significant difference in the liver regeneration ratio. The type of remnant liver (P < .001), RLV/body weight (P = .027), RLV/TLV (P < .001), serum albumin on postoperative day 7 and total bilirubin levels on postoperative day 30 were the most significant factors affecting liver regeneration in living donors. In conclusion, adequate liver regeneration is essential for donor outcome after liver donation. The remnant liver could eventually regenerate to an adequate volume similar to the initial TLV before liver donation. However, the remnant left hemi-liver had a faster growth rate than the remnant right hemi-liver in donors.

Impact of Omicron variant infection on the liver, kidney, and coagulation system in patients undergoing elective surgery: a retrospective case-control study.

Purpose: We aimed to investigate the impact of Omicron variant infection on the perioperative organ function in patients undergoing elective surgery. Methods: A total of 5029 patients who underwent elective surgery between October 2022 and January 2023 at our hospital were enrolled. Among them, the patients who underwent elective surgery between October 2022 and November 2022 composed Group 1 (not infected with the Omicron variant) the control group; those who underwent elective surgery between December 2022 and January 2023 composed Group 2 (one month after Omicron variant infection) the experimental group. We further divided the patients into two subgroups for analysis: the tumor subgroup and the nontumor subgroup. Data on organ system function indicators, including coagulation parameters, liver function, complete blood count (CBC), and kidney function, were collected before and after surgery. Differences between the two groups were subsequently analyzed via binary logistic regression analysis. Results: Compared with those in the uninfected patient group, the following changes were observed in patients with Omicron variant infection who underwent elective surgery one month after infection: prothrombin activity (PTa), prothrombin time (PT), fibrinogen, albumin/globulin, alanine aminotransferase (ALT), mean corpuscular hemoglobin concentration (MCHC), platelet (PLT), and anemia were increased AST/ALT, indirect bilirubin (IBILI), eosinophils, and uric acid were decreased before surgery; and lung infection/pneumonia and fibrinogen were increased, while AST/ALT, globulin, total bilirubin (TBIL), white blood cell count (WBC), and uric acid were decreased after surgery. There was no significant difference in the mortality rate or length of hospital stay (LOS) between the two groups. Subgroup analysis revealed elevated monocyte, PLT, and fibrinogen classification, levels and decreased globulin, prealbumin (PBA), eosinophil, and uric acid levels in the tumor subgroup of patients who underwent elective surgery one month after Omicron infection compared with those in the uninfected patients. Compared with the nontumor subgroup, fibrinogen levels, lung infection/pneumonia, TBIL, and PLT count were increased in the uninfected patients, while the globulin and eosinophil levels were decreased. Conclusion: Compared with uninfected patients, patients who underwent elective surgery one month after Omicron variant infection exhibited minimal changes in perioperative coagulation parameters, liver function, CBC counts, and kidney function. Additionally, no significant differences in postoperative mortality or LOS were observed between the two groups.

Decreased mebrofenin uptake in patients with non-colorectal liver tumors requiring liver volume augmentation-a single-center analysis.

BACKGROUND: Posthepatectomy liver failure (PHLF) remains a life-threatening complication after hepatectomy. To reduce PHLF, a preoperative assessment of liver function is indispensable. For this purpose, 99mTc-mebrofenin hepatobiliary scintigraphy with SPECT (MSPECT) can be used. The aim of the current study was to evaluate the predictive value of MSPECT for PHLF in patients with non-colorectal liver tumors (NCRLT) compared to patients with colorectal liver metastasis (CRLM) undergoing extended liver resection. METHODS: We included all patients undergoing extended liver resections via two-stage procedures between January 2019 and December 2021 at the University Medical Center Hamburg-Eppendorf, Germany. All patients received a preoperative MSPECT. RESULTS: Twenty patients were included. In every fourth patient, PHLF was observed. Four patients had PHLF grade C. There were no differences between patients with CRLM and NCRLT regarding PHLF rate and future liver remnant (FLR) volume. Patients with CRLM had higher mebrofenin uptake in the FLR compared to those with NCRLT (2.49%/min/m2 vs. 1.51%/min/m2; p = 0.004). CONCLUSION: Mebrofenin uptake in patients with NCRLT was lower compared to those patients with CRLM. However, there was no difference in the PHLF rate and FLR volume. Cut-off values for the mebrofenin uptake might need adjustments for different surgical indications, surgical procedures, and underlying diseases.

SwinD-Net: a lightweight segmentation network for laparoscopic liver segmentation.

The real-time requirement for image segmentation in laparoscopic surgical assistance systems is extremely high. Although traditional deep learning models can ensure high segmentation accuracy, they suffer from a large computational burden. In the practical setting of most hospitals, where powerful computing resources are lacking, these models cannot meet the real-time computational demands. We propose a novel network SwinD-Net based on Skip connections, incorporating Depthwise separable convolutions and Swin Transformer Blocks. To reduce computational overhead, we eliminate the skip connection in the first layer and reduce the number of channels in shallow feature maps. Additionally, we introduce Swin Transformer Blocks, which have a larger computational and parameter footprint, to extract global information and capture high-level semantic features. Through these modifications, our network achieves desirable performance while maintaining a lightweight design. We conduct experiments on the CholecSeg8k dataset to validate the effectiveness of our approach. Compared to other models, our approach achieves high accuracy while significantly reducing computational and parameter overhead. Specifically, our model requires only 98.82 M floating-point operations (FLOPs) and 0.52 M parameters, with an inference time of 47.49 ms per image on a CPU. Compared to the recently proposed lightweight segmentation network UNeXt, our model not only outperforms it in terms of the Dice metric but also has only 1/3 of the parameters and 1/22 of the FLOPs. In addition, our model achieves a 2.4 times faster inference speed than UNeXt, demonstrating comprehensive improvements in both accuracy and speed. Our model effectively reduces parameter count and computational complexity, improving the inference speed while maintaining comparable accuracy. The source code will be available at https://github.com/ouyangshuiming/SwinDNet.

Liver resection volume-dependent pancreatic strain following living donor hepatectomy.

The liver and pancreas work together to recover homeostasis after hepatectomy. This study aimed to investigate the effect of liver resection volume on the pancreas. We collected clinical data from 336 living liver donors. They were categorized into left lateral sectionectomy (LLS), left lobectomy, and right lobectomy (RL) groups. Serum pancreatic enzymes were compared among the groups. Serum amylase values peaked on postoperative day (POD) 1. Though they quickly returned to preoperative levels on POD 3, 46% of cases showed abnormal values on POD 7 in the RL group. Serum lipase levels were highest at POD 7. Lipase values increased 5.7-fold on POD 7 in the RL group and 82% of cases showed abnormal values. The RL group's lipase was twice that of the LLS group. A negative correlation existed between the remnant liver volume and amylase (r = - 0.326)/lipase (r = - 0.367) on POD 7. Furthermore, a significant correlation was observed between POD 7 serum bilirubin and amylase (r = 0.379)/lipase (r = 0.381) levels, indicating cooccurrence with liver and pancreatic strain. Pancreatic strain due to hepatectomy occurs in a resection/remnant liver volume-dependent manner. It would be beneficial to closely monitor pancreatic function in patients undergoing a major hepatectomy.

Ultrasound-guided percutaneous high-frequency irreversible electroporation in porcine livers using four electrode needles: A feasibility and safety study.

BACKGROUND: Malignant liver tumors seriously endanger human health. Among different therapeutic approaches, high-frequency irreversible electroporation (H-FIRE) is a recently emerging tumor ablation technique. The objective of this study was to evaluate the feasibility and safety of ultrasound-guided percutaneous H-FIRE using four electrode needles in porcine livers. METHODS: Twelve experimental pigs underwent percutaneous H-FIRE ablation using a compound steep-pulse therapeutic device. Liver tissues adjacent to the gallbladder, blood vessels, and bile ducts were selected as the ablation targets. Pigs were randomly divided into three groups: (1) immediately after ablation (N = 4), (2) 2 days after ablation (N = 4), and (3) 7 days after ablation (N = 4). Blood routine, liver and kidney function, and myocardial enzyme levels were measured before and after ablation. Ultrasound, contrast-enhanced ultrasound (CEUS), contrast-enhanced magnetic resonance imaging (MRI), and hematoxylin-eosin staining were performed to evaluate the ablation performance. RESULTS: Ultrasound-guided percutaneous H-FIRE ablations using four electrode needles were successfully performed in all 12 experimental pigs. The general conditions of the pigs, including postoperative activities and feeding behaviors, were normal, with no significant changes compared with the preoperative conditions. The imaging features of ultrasound, CEUS, and MRI demonstrated no significant changes in the gallbladder walls, bile ducts, or blood vessels close to the ablation areas. Laboratory tests showed that liver function indices and myocardial enzymes increased temporarily after H-FIRE ablation, but decreased to normal levels at 7 days after ablation. Histopathological examinations of porcine liver specimens showed that this technique could effectively ablate the target areas without damaging the surrounding or internal vascular systems and gallbladder. CONCLUSIONS: This study demonstrated the feasibility and safety of ultrasound-guided percutaneous H-FIRE ablation in porcine livers in vivo, and proposed a four-needle method to optimize its clinical application.

Efficacy of surgical staple line reinforcement in Glissonean stapling: A single-center pilot study.

Vascular staplers are routinely used in laparoscopic liver resection, which has become a standard procedure in advanced medical facilities. Although previous reports have outlined the benefits of staple line reinforcement (SLR), its application in Glissonean pedicle transection during hepatic resection remains poorly studied. This study investigated surgical SLR as a tool to enhance staple line strength and improve perioperative hemostasis. Here, 10 patients who underwent laparoscopic liver resection using the Tri-StapleTM2.0 Reinforced Reload were included. Patient characteristics, surgical details, and outcomes were assessed. The results demonstrated successful outcomes with no complications related to bile leakage or injuries during staple insertion. Overall, our findings suggest that SLR can be safely utilized in Glissonean pedicle transection during laparoscopic liver resections. Further studies are required to comprehensively evaluate its benefits compared with conventional surgical staplers.

Research on workflow recognition for liver rupture repair surgery.

Liver rupture repair surgery serves as one tool to treat liver rupture, especially beneficial for cases of mild liver rupture hemorrhage. Liver rupture can catalyze critical conditions such as hemorrhage and shock. Surgical workflow recognition in liver rupture repair surgery videos presents a significant task aimed at reducing surgical mistakes and enhancing the quality of surgeries conducted by surgeons. A liver rupture repair simulation surgical dataset is proposed in this paper which consists of 45 videos collaboratively completed by nine surgeons. Furthermore, an end-to-end SA-RLNet, a self attention-based recurrent convolutional neural network, is introduced in this paper. The self-attention mechanism is used to automatically identify the importance of input features in various instances and associate the relationships between input features. The accuracy of the surgical phase classification of the SA-RLNet approach is 90.6%. The present study demonstrates that the SA-RLNet approach shows strong generalization capabilities on the dataset. SA-RLNet has proved to be advantageous in capturing subtle variations between surgical phases. The application of surgical workflow recognition has promising feasibility in liver rupture repair surgery.

Low Pneumoperitoneum Pressure Reduces Gas Embolism During Laparoscopic Liver Resection: A Randomized Controlled Trial.

OBJECTIVE: To compare the effect of low and standard pneumoperitoneal pressure (PP) on the occurrence of gas embolism during laparoscopic liver resection (LLR). BACKGROUND: LLR has an increased risk of gas embolism. Although animal studies have shown that low PP reduces the occurrence of gas embolism, clinical evidence is lacking. METHODS: This parallel, dual-arm, double-blind, randomized controlled trial included 141 patients undergoing elective LLR. Patients were randomized into standard ("S," 15 mm Hg; n = 70) or low ("L," 10 mm Hg; n = 71) PP groups. Severe gas embolism (≥ grade 3, based on the Schmandra microbubble method) was detected using transesophageal echocardiography and recorded as the primary outcome. Intraoperative vital signs and postoperative recovery profiles were also evaluated. RESULTS: Fewer severe gas embolism cases (n = 29, 40.8% vs n = 47, 67.1%, P = 0.003), fewer abrupt decreases in end-tidal carbon dioxide partial pressure, shorter severe gas embolism duration, less peripheral oxygen saturation reduction, and fewer increases in heart rate and lactate during gas embolization episodes was found in group L than in group S. Moreover, a higher arterial partial pressure of oxygen and peripheral oxygen saturation were observed, and fewer fluids and vasoactive drugs were administered in group L than in group S. In both groups, the distensibility index of the inferior vena cava negatively correlated with central venous pressure throughout LLR, and a comparable quality of recovery was observed. CONCLUSIONS: Low PP reduced the incidence and duration of severe gas embolism and achieved steadier hemodynamics and vital signs during LLR. Therefore, a low PP strategy can be considered a valuable choice for the future LLR.

In vivo evaluation of focused ultrasound ablation surgery (FUAS)-induced coagulation using echo amplitudes of the therapeutic focused ultrasound transducer.

OBJECTIVE: Monitoring sensitivity of sonography in focused ultrasound ablation surgery (FUAS) is limited (no hyperechoes in ∼50% of successful coagulation in uterine fibroids). A more accurate and sensitive approach is required. METHOD: The echo amplitudes of the focused ultrasound (FUS) transducer in a testing mode (short pulse duration and low power) were found to correlate with the ex vivo coagulation. To further evaluate its coagulation prediction capabilities, in vivo experiments were carried out. The liver, kidney, and leg muscles of three adult goats were treated using clinical FUAS settings, and the echo amplitude of the FUS transducer and grayscale in sonography before and after FUAS were collected. On day 7, animals were sacrificed humanely, and the treated tissues were dissected to expose the lesion. Echo amplitude changes and lesion areas were analyzed statistically, as were the coagulation prediction metrics. RESULTS: The echo amplitude changes of the FUS transducer correlate well with the lesion areas in the liver (R = 0.682). Its prediction in accuracy (94.4% vs. 50%), sensitivity (92.9% vs. 35.7%), and negative prediction (80% vs. 30.8%) is better than sonography, but similar in specificity (80% vs. 100%) and positive prediction (100% vs. 100%). In addition, the correlation between tissue depth and the lesion area is not good (|R| < 0.2). Prediction performances in kidney and leg muscles are similar. CONCLUSION: The FUS echo amplitudes are sensitive to the tissue properties and their changes after FUAS. They are sensitive and reliable in evaluating and predicting FUAS outcomes.

[Clinical application of split liver transplantation: a single center report of 203 cases].

Objective: To investigate the safety and therapeutic effect of split liver transplantation (SLT) in clinical application. Methods: This is a retrospective case-series study. The clinical data of 203 consecutive SLT, 79 living donor liver transplantation (LDLT) and 1 298 whole liver transplantation (WLT) performed at the Third Affiliated Hospital of Sun Yat-sen University from July 2014 to July 2023 were retrospectively analyzed. Two hundred and three SLT liver grafts were obtained from 109 donors. One hundred and twenty-seven grafts were generated by in vitro splitting and 76 grafts were generated by in vivo splitting. There were 90 adult recipients and 113 pediatric recipients. According to time, SLT patients were divided into two groups: the early SLT group (40 cases, from July 2014 to December 2017) and the mature SLT technology group (163 cases, from January 2018 to July 2023). The survival of each group was analyzed and the main factors affecting the survival rate of SLT were analyzed. The Kaplan-Meier method and Log-rank test were used for survival analysis. Results: The cumulative survival rates at 1-, 3-, and 5-year were 74.58%, 71.47%, and 71.47% in the early SLT group, and 88.03%, 87.23%, and 87.23% in the mature SLT group, respectively. Survival rates in the mature SLT group were significantly higher than those in the early SLT group (χ2=5.560,P=0.018). The cumulative survival rates at 1-, 3- and 5-year were 93.41%, 93.41%, 89.95% in the LDLT group and 87.38%, 81.98%, 77.04% in the WLT group, respectively. There was no significant difference among the mature SLT group, the LDLT group and the WLT group (χ2=4.016, P=0.134). Abdominal hemorrhage, infection, primary liver graft nonfunction,and portal vein thrombosis were the main causes of early postoperative death. Conclusion: SLT can achieve results comparable to those of WLT and LDLT in mature technology liver transplant centers, but it needs to go through a certain time learning curve.

Microfracture-coagulation for the real robotic liver parenchymal transection.

The use of the robotic approach in liver surgery is exponentially increasing. Although technically the robot introduces several innovative features, the instruments linked with the traditional laparoscopic approach for the liver parenchymal transection are not available, which may result in multiple technical variants that may bias the comparative analysis between the different series worldwide. A real robotic approach, minimally efficient for the liver parenchymal transection, with no requirement of external tool, available for the already existing platforms, and applicable to any type of liver resection, counting on the selective use of the plugged bipolar forceps and the monopolar scissors, or "microfracture-coagulation" (MFC) transection method, is described in detail. The relevant aspects of the technique, its indications and methodological basis are discussed.

Characterization of Blood-Brain Barrier Opening Induced by Transcranial Histotripsy in Murine Brains.

OBJECTIVE: Transcranial histotripsy has shown promise as a non-invasive neurosurgical tool, as it has the ability to treat a wide range of locations in the brain without overheating the skull. One important effect of histotripsy in the brain is the blood-brain barrier (BBB) opening (BBBO) at the ablation site, but there is a knowledge gap concerning the extent of histotripsy-induced BBBO. Here we describe induction of BBBO by transcranial histotripsy and use of magnetic resonance imaging (MRI) and histology to quantify changes in BBBO at the periphery of the histotripsy ablation zone over time in the healthy mouse brain. METHODS: An eight-element, 1 MHz histotripsy transducer with a focal distance of 32.5 mm was used to treat the brains of 23 healthy female BL6 mice. T1-gadolinium (T1-Gd) MR images were acquired immediately following histotripsy treatment and during each of the subsequent 4 wk to quantify the size and intensity of BBB leakage. RESULTS: The T1-Gd MRI results revealed that the hyperintense BBBO volume increased over the first week and subsided gradually over the following 3 wk. Histology revealed complete loss of tight junction proteins and blood vessels in the center of the ablation region immediately after histotripsy, partial recovery in the periphery of the ablation zone 1 wk following histotripsy and near-complete recovery of tight junction complex after 4 wk. CONCLUSION: These results provide the first evidence of transcranial histotripsy-induced BBBO and repair at the periphery of the ablation zone.