Our Providers

All professionals at Advanced Gastroenterology Group maintain the highest levels of accreditation and pursue ongoing education to stay abreast of the latest trends in the medical field. Read on to learn more about our staff's experience and training.

Patrick G. Tempera, MD, AGAF

Dr. Tempera is a gastroenterologist on staff at Trinitas Medical Center and Overlook Medical Center, New Jersey. He completed his medical residency in internal medicine at St. Michael’s Medical Center in Newark, New Jersey as chief resident. . He completed his fellowship training in gastroenterology at Seton Hall University Post Graduate School of Medicine. Dr. Tempera is board certified in gastroenterology and internal medicine. He is a fellow of the American Gastroenterology Association.

Dr. Tempera received multiple awards including Attending of the year at Trinitas Medical Center, Union Hospital, and Overlook Hospital. He is named as one of New Jersey’s Top Docs for the years 2004 through 2015. Dr. Tempera is an Associate Professor of medicine at New York College of Osteopathic Medicine, and Seton Hall University Post Graduate Medicine. He has served as President of the New Jersey Gastroenterology Society and New Jersey Society of Endoscopy. Dr. Tempera teaches residents in Internal Medicine and Family practice at Overlook Medical Center. Dr. Tempera is also a member of the Contractor Advisory Committee for Medicare representing New Jersey’s Gastroenterologists.

Rajesh Dhirmalani, DO

Holding a Doctorate in Osteopathic Medicine from Des Moines College of Osteopathic Medicine, Dr. Dhirmalani is board certified in Gastroenterology and Internal Medicine, and served as an Assistant Professor at the University of Medicine and Dentistry of New Jersey. He has trained at a liver transplant unit and is well versed in the latest endoscopic ultrasound approaches and advanced therapeutics, including hemorrhoidal therapy. Dr. Dhirmalani has been involved in curriculum formulation and is published on a variety of Digestive Disease topics, resulting in invitations to present at industry conferences.

Kunal Grover, MD

Dr. Grover graduated from St. George’s University School of Medicine in 2003. He completed his Internship and Residency in Internal Medicine at Rutgers/University of Medicine and Dentistry of New Jersey, where he went on to complete a Fellowship in Gastroenterology. During Dr. Grover’s tenure at Rutgers he served as both Chief Medical Resident and Chief Gastroenterology Fellow.

Born and raised in New Jersey – Dr. Grover is happy to serve a community that he grew up in. He has been with AGG since 2010. Dr. Grover treats a wide variety of GI conditions and performs numerous procedures including EGD, Colonoscopy, Endoscopic Ultrasound with fine needle aspiration (biopsy), and ERCP. Dr Grover was awarded NJ Top Doc in 2017 and 2018 as well as VITALS Compassionate Doctor and Patient Choice awards.

Dr Grover is a football fanatic, who is a diehard Jets fan. He is also an avid comic book collector, collecting since he was 15 years old.

Michael J. Viksjo, MD, AGAF

Dr. Michael Viksjo grew up in Buffalo, New York and went to the University at Buffalo School of Medicine before moving to the tristate area. He completed his residency in Internal Medicine at Montefiore Medical Center, the University Hospital for the Albert Einstein College of Medicine in the Bronx. After later finishing his Gastroenterology fellowship at New Jersey Medical School in Newark, NJ, he spent 5 years in private practice at Hackensack University Medical Center before joining Advanced Gastroenterology Group here in Union County in March of 2015. 

He currently works out of both Overlook Medical Center in Summit, New Jersey and Trinitas Regional Medical Center in Elizabeth, New Jersey (where he also serves as the Academic Chief of the Gastroenterology teaching service). Dr. Viksjo is a member of the American College of Gastroenterology and the American Society of Gastrointestinal Endoscopy, is a Fellow of the American Gastroenterology Association, and is a former President of the New Jersey Gastroenterology and Endoscopy Society. 

Dr. Viksjo sees patients with all types of Gastrointestinal and Liver disease, but specializes in the diseases of the liver, bile ducts, and pancreas with the use of advanced endoscopic procedures like Endoscopic Ultrasound with fine needle aspiration and therapeutic Endoscopic Retrograde Cholangiopancreatography.

Guida St. George, MS, PA-C

Guida St. George, MS, PA-C is a graduate of the University of Medicine and Dentistry of NJ and Seton Hall University. She holds a Masters of Science in Physician Assistant Studies and a BA in Biology.

She is certified as a Physician Assistant by the National Commission on Certification of Physician Assistants (NCCPA).

Guida is a recipient of the Certificate of Excellence in Research Award and an accredited member of the New Jersey State Society of Physician Assistants and the American Academy of Physician Assistants. She holds certifications from the American Heart Association for Basic Life Support as well as Advanced Cardiac and Pediatric Life Support.

She specializes in digestive diseases and weight loss management and has been a Gastroenterology Physician Assistant at Advanced Gastroenterology Group since 2002.

Guida is fluent in Portuguese and Spanish.

Tracey Alves, ANP

Tracey Alves is a graduate of Seton Hall University where she received her Bachelors of Science in Nursing. She also holds a Master's degree in Nursing from Walden University where she graduated with honors. In 2012, Tracey began her professional career as a registered nurse at Overlook Medical Center and Saint Barnabas Medical Center while completing her Advanced Practice Nursing Degree. 

She has worked at Advanced Gastroenterology Group for the past several years as a Nurse Practitioner. Tracey is certified by the American Association of Nurse Practitioners (AANP). She is also a member of the American Association of Nurse Practitioners and Sigma Theta Tau International, the Honor Society of Nursing. She holds certifications from the American Heart Association in basic, advanced cardiac and pediatric life support. 

Outside of work, she enjoys family time with her husband and children. She enjoys reading for leisure, traveling and experiencing new foods and new cultures. Tracey is fluent in Portuguese and Spanish.

Prakriti Merchant, MD

Dr. Merchant is dual board certified in Gastroenterology and Internal Medicine. She graduated from St. George's University Medical School and subsequently completed her Internal Medicine training at Norwalk Hospital, CT. She obtained her Gastroenterology and Hepatology degree from Norwalk Hospital and Yale New Haven Medical Center.

Dr. Merchant currently has privileges at Overlook Hospital, Summit NJ and Trinitas Medical Center, Elizabeth NJ.

She is a member of the American Gastroenterology Association, American College of Gastroenterology, American Society of Gastrointestinal Endoscopy and American Medical Association.

Arun Mathew, MD

Dr. Mathew grew up in the Bergen County Area and went to Lehigh University for his undergraduate education before returning to Newark, NJ for his medical education at New Jersey Medical School. In medical school, he was nominated by his peers for admission into the Gold Humanism Honor Society for compassionate care of his patients . He went on to train in internal medicine at Thomas Jefferson University Hospital in Philadelphia, PA and then gastroenterology training at Lankenau Medical Center in Wynnewood, PA. He is published in multiple papers in the field of gastroenterology and hepatology.

He currently works out of Overlook Medical Center in Summit, NJ and Trinitas Regional Medical Center in Elizabeth, NJ. Dr Mathew is currently a member of the American College of Gastroenterology and the American Gastroenterology Association. 

Outside of work, he has maintained being a NY Giants fan despite living in Philadelphia for 6 years and enjoys traveling and snowboarding.