Mark G. van Vledder
Johns Hopkins University
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Featured researches published by Mark G. van Vledder.
Hpb | 2011
Peter D. Peng; Mark G. van Vledder; Susan Tsai; Mechteld C. de Jong; Martin A. Makary; Julie Ng; Barish H. Edil; Christopher L. Wolfgang; Richard D. Schulick; Michael A. Choti; Ihab R. Kamel; Timothy M. Pawlik
BACKGROUND As indications for liver resection expand, objective measures to assess the risk of peri-operative morbidity are needed. The impact of sarcopenia on patients undergoing liver resection for colorectal liver metastasis (CRLM) was investigated. METHODS Sarcopenia was assessed in 259 patients undergoing liver resection for CRLM by measuring total psoas area (TPA) on computed tomography (CT). The impact of sarcopenia was assessed after controlling for clinicopathological factors using multivariate modelling. RESULTS Median patient age was 58 years and most patients (60%) were male. Forty-one (16%) patients had sarcopenia (TPA ≤ 500 mm(2) /m(2) ). Post-operatively, 60 patients had a complication for an overall morbidity of 23%; 26 patients (10%) had a major complication (Clavien grade ≥3). The presence of sarcopenia was strongly associated with an increased risk of major post-operative complications [odds ratio (OR) 3.33; P= 0.008]. Patients with sarcopenia had longer hospital stays (6.6 vs. 5.4 days; P= 0.03) and a higher chance of an extended intensive care unit (ICU) stay (>2 days; P= 0.004). On multivariate analysis, sarcopenia remained independently associated with an increased risk of post-operative complications (OR 3.12; P= 0.02). Sarcopenia was not significantly associated with recurrence-free [hazard ratio (HR) = 1.07] or overall (HR = 1.05) survival (both P > 0.05). CONCLUSIONS Sarcopenia impacts short-, but not long-term outcomes after resection of CRLM. While patients with sarcopenia are at an increased risk of post-operative morbidity and longer hospital stay, long-term survival is not impacted by the presence of sarcopenia.
Journal of Gastrointestinal Surgery | 2010
Mark G. van Vledder; Mechteld C. de Jong; Timothy M. Pawlik; Richard D. Schulick; Luis A. Diaz; Michael A. Choti
BackgroundWith increasing efficacy of preoperative chemotherapy for colorectal cancer, more patients will present with one or more disappearing liver metastases (DLM) on preoperative cross-sectional imaging.Patients and MethodsA retrospective review was conducted evaluating the radiological response to preoperative chemotherapy for 168 patients undergoing surgical therapy for colorectal liver metastases at Johns Hopkins Hospital between 2000 and 2008.ResultsForty patients (23.8%) had one or more DLM, accounting for a total of 127 lesions. In 22 patients (55%), all DLM sites were treated during surgery. Of the 17 patients with unidentified, untreated DLM, ten patients (59%) developed a local recurrence at the initial site, half of which also developed recurrences in other sites. While the intrahepatic recurrence rate was higher for patients with DLM left in situ (p = 0.04), the 1-, 3-, and 5-year overall survival rate was not significantly different for patients with DLM left in situ (93.8%, 63.5%, and 63.5%, respectively) when compared to patients with a radiological chemotherapy response in whom all original disease sites were surgically treated (92.3%, 70.8%, and 46.2%, respectively; p = 0.66).ConclusionsDLM were frequently observed in patients undergoing preoperative chemotherapy for liver metastases. Survival was comparable in patients with untreated DLM, in spite of high intrahepatic recurrence rates seen in these patients. Therefore, aggressive surgical therapy should be considered in patients with marked response to chemotherapy, even when all DLM sites cannot be identified.
Journal of Surgical Oncology | 2010
Mechteld C. de Jong; Susan Tsai; John L. Cameron; Christopher L. Wolfgang; Kenzo Hirose; Mark G. van Vledder; Frederic E. Eckhauser; Joseph M. Herman; Barish H. Edil; Michael A. Choti; Richard D. Schulick; Timothy M. Pawlik
The management of patients with peri‐ampullary liver metastasis remains controversial. We sought to assess the safety and efficacy of curative intent surgery for peri‐ampullary liver metastasis.
Hpb | 2010
Mark G. van Vledder; Emad M. Boctor; Lia Assumpcao; Hassan Rivaz; Pezhman Foroughi; Gregory D. Hager; Ulrike M. Hamper; Timothy M. Pawlik; Michael A. Choti
BACKGROUND Thermal ablation is an accepted therapy for selected hepatic malignancies. However, the reliability of thermal ablation is limited by the inability to accurately monitor and confirm completeness of tumour destruction in real time. We investigated the ability of ultrasound elasticity imaging (USEI) to monitor thermal ablation. OBJECTIVES Capitalizing on the known increased stiffness that occurs with protein denaturation and dehydration during thermal therapy, we sought to investigate the feasibility and accuracy of USEI for monitoring of liver tumour ablation. METHODS A model for hepatic tumours was developed and elasticity images of liver ablation were acquired in in vivo animal studies, comparing the elasticity images to gross specimens. A clinical pilot study was conducted using USEI in nine patients undergoing open radiofrequency ablation for hepatic malignancies. The size and shape of thermal lesions on USEI were compared to B-mode ultrasound and post-ablation computed tomography (CT). RESULTS In both in vivo animal studies and in the clinical trial, the boundary of thermal lesions was significantly more conspicuous on USEI when compared with B-mode imaging. Animal studies demonstrated good correlation between the diameter of ablated lesions on USEI and the gross specimen (r = 0.81). Moreover, high-quality strain images were generated in real time during therapy. In patients undergoing tumour ablation, a good size correlation was observed between USEI and post-operative CT (r = 0.80). CONCLUSION USEI can be a valuable tool for the accurate monitoring and real-time verification of successful thermal ablation of liver tumours.
Archives of Surgery | 2010
Mark G. van Vledder; Michael Torbenson; Timothy M. Pawlik; Emad M. Boctor; Ulrike M. Hamper; Kelly Olino; Michael A. Choti
OBJECTIVE To investigate the association of relative tumor echogenicity and hepatic steatosis in patients undergoing resection of colorectal liver metastases (CRLM). DESIGN Prospective study. SETTING The Johns Hopkins Hospital. PATIENTS A total of 126 patients undergoing liver surgery for CRLM from January 1, 1998, through December 31, 2008, in whom 191 lesions had complete intraoperative ultrasonography images for review and adequate linked pathological data available. MAIN OUTCOME MEASURES The intraoperative ultrasonography images were reviewed and scored for echogenicity (hypoechoic, isoechoic, or hyperechoic). In addition, a histopathologic review of the nontumorous liver tissue was performed, and the extent of steatosis was scored and correlated with tumor echogenicity. RESULTS Of the patients undergoing surgery, 49 (38.8%) were found to have mild to severe steatosis. Of the 191 total CRLM visualized by intraoperative ultrasonography, 91 (47.6%) were found to be hypoechoic, 65 (34.0%) were isoechoic, and 35 (18.3%) were hyperechoic. In patients with steatosis, lesions were significantly more likely to be hypoechoic when compared with patients without steatosis (odds ratio, 4.17; 95% confidence interval, 1.87-8.47; P = .001). Echogenicity was independent of the cause of steatosis or response to chemotherapy. CONCLUSIONS The echogenicity of CRLM was significantly affected by the presence of liver steatosis, with decreased echogenicity and increased conspicuity of lesions despite overall poorer image quality. These findings might reinforce the usefulness of intraoperative ultrasonography in identifying additional CRLM in patients undergoing surgical therapy, even in those with fatty liver tissue.
Annals of Surgical Oncology | 2010
Mark G. van Vledder; Timothy M. Pawlik; Sanjay Munireddy; Ulrike M. Hamper; Mechteld C. de Jong; Michael A. Choti
Journal of Gastrointestinal Surgery | 2011
Mechteld C. de Jong; Mark G. van Vledder; Dario Ribero; Catherine Hubert; Jean-François Gigot; Michael A. Choti; Richard D. Schulick; Lorenzo Capussotti; Cornelis H.C. Dejong; Timothy M. Pawlik
Ultrasound in Medicine and Biology | 2013
Pezhman Foroughi; Hyun Jae Kang; Daniel Carnegie; Mark G. van Vledder; Michael A. Choti; Gregory D. Hager; Emad M. Boctor
Journal of Vascular and Interventional Radiology | 2011
Mark G. van Vledder; Lia Assumpcao; Sanjay Munireddy; Kartik Sehgal; Emad M. Boctor; Michael A. Choti
Archive | 2016
Mark G. van Vledder; Michael A. Choti; Vinícius Grando Gava; Silvio Marcio Pegoraro Balzan