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Houston: 281.565.0033
Austin: 512.551.1403
San Antonio: 210.504.4304

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If you would like to avoid the wait, you can speak to one of our representatives by calling (281) 565-0033.


Meet our Staff

At Hamilton Vein Center, we truly believe in the teamwork approach. Through the course of your treatment, you will be seen by our doctors and our mid-level providers to ensure that you receive the best possible care. Our physicians and mid-levels truly work as a team and communicate extensively. They work closely with each other to discuss cases, diagnoses and treatments though your treatment is always supervised by the doctor. Our physician assistants are trained personally and thoroughly by Dr. Hamilton and our team of interventional radiologists.


Carlos R. Hamilton III – MD

Founder and Medical Director

Dr.Carlos R. Hamilton III MDDr. Hamilton graduated Magna Cum Laude and Alpha Omega Alpha from the University of Texas Medical Branch in Galveston in 1994. Here, Dr. Hamilton was chief resident during his diagnostic radiology residency. He completed his Fellowship at University of Texas Southwestern Medical Center in Dallas, and then returned to Houston to practice in his hometown. Dr. Hamilton has been servicing the Houston community as both a diagnostic and interventional radiologist since 1999. He opened the Hamilton Institute, now Hamilton Vein Center, in Sugar Land in 2010.

See Dr. Hamilton’s extended bio



Michael Di Iorio – MD, RPVI, RPhS

Dr. Di Iorio graduated from Rutgers University Robert Wood Johnson Medical School. After completing an internship in general surgery and a residency in radiology he went on to complete a fellowship in vascular & interventional radiology at Brown University. He is board certified by the American Board of Radiology and holds a Certificate of Added Qualification in Vascular & Interventional Radiology. Dr. Di Iorio achieved added certification in vein disease treatment becoming a Diplomate of the American Board of Venous & Lymphatic Medicine. An active member of the American College of Phlebology, Dr. Di Iorio is the Chair of the CME Education Development Committee and the co-creator of the college’s Case of the Month series. He was selected as a member of the inaugural class of the American College of Phlebology’s Leadership Academy. A father of three daughters, he enjoys spending time with his family, exercising and cooking.


Sheri Macrino – MD

Prior to joining the team at Hamilton Vein Center, Dr. Macrino served as assistant medical director of outpatient imaging and vein center in Pittsburgh, PA. Dr. Macrino graduated from Gannon University in 2001 with a BS in Biology. She then completed her medical degree at Penn State University College of Medicine and went on to do her residency training in diagnostic radiology. Her residency was followed by a fellowship in interventional radiology within the West Penn Allegheny Health System in Pittsburgh. Dr. Macrino will be seeing patients at Hamilton Vein Center Katy. Outside of work, Dr. Macrino likes to work out, travel, and spend time with her husband and dogs.


Justin G. Smith– MD

Dr. Smith graduated Magna Cum Laude from Texas A&M University and is a member of the Honor Society, Alpha Omega Alpha. Before joining Hamilton Vein Center, Dr. Smith served as Medical Director at an outpatient Interventional practice in Dallas. He completed a Radiology Residency from University of Texas – Houston as well as a fellowship in Vascular and Interventional Radiology from MD Anderson in Houston. When he isn’t working, Dr. Smith enjoys spending time with his wife and two dogs, building custom Jeeps, water sports and traveling.



AJ Valenson – MD

Dr. Valenson, a Clear Lake native, graduated from Yale Medical School in New Haven, Connecticut, and completed a two-year internship in surgical training in Chicago before returning to Yale for a residency in radiology. Prior to this, he received his bachelor’s degree from the University of Houston. He is a native Spanish speaker and is happy to be returning to his hometown to practice medicine. His interests and activities include sports, the outdoors, and reading.





Tina – PA-C

Tina graduated with her bachelor’s of science degree from St. John’s University, New York in 2000. She earned her Physician Assistant certification through St. Vincent’s Catholic Medical Center, NY. She has worked in the fields of Gyn and infertility, general, vascular and breast surgery. Most recently, Tina spent five years at West Houston Medical Center as the quality manager for performance improvement. She joined the Hamilton Vein team in January 2014. Tina is fluent in Malayalam, an Indian language spoken primarily in Kerala. Our patients are always happy to see Tina.



Sarah – PA-C

Sarah graduated with a bachelor’s of science degree from Texas A&M University and earned a master’s degree in physician assistant studies from the Baylor College of Medicine.  Sarah has been working at the Hamilton Vein Center since May 2012.  Prior to that she worked at an internal medicine practice in Phoenix, Arizona.






Meagan – PA-C

Meagan graduated from Oklahoma State University with a bachelor’s of science degree in nutrition and then went on to obtain her master’s degree in physician assistant studies at Baylor College of Medicine. Meagan worked in Surgical Oncology before joining Hamilton Vein Center.






Heather – RPA

Heather is a Radiologist Practitioner Assistant. She completed her undergraduate degree at the University of Texas. Upon graduation, Heather completed her Radiologist Practitioner Assistant training at Weber State University. With extensive experience in vein treatment, Heather was a welcome addition to the Hamilton Vein Center team in November of 2011.






Chris – PA-C

Chris graduated with a bachelor of science in Nursing from Bradley University in Peoria, IL and practiced as a Critical Care RN for 10 years prior to becoming a PA. She went on to earn her BS in PA studies from Midwestern University, and her Master’s degree in Business Administration from Keller Graduate School in Chicago. For the last 16 years, Chris has practiced as a PA in Cardiovascular and Thoracic Surgery, and Neurointerventional Radiology. Chris joined the Hamilton Vein team in January 2014.





Tawanna – RN

As a registered nurse, Tawanna brings 10 years of nursing experience to Hamilton Vein Center. Her calm personality combined with her experience help make patients feel relaxed during procedures.








Huy – RVT

Huy graduated from Rush University in Chicago, Illinois with a bachelor’s of science degree in vascular ultrasound. Huy brings many years of experience in ultrasound. Before joining Hamilton Vein Center, he worked at another vein center and also at UTMB Galveston vascular lab.






Shauna – PA-C

Shauna graduated with a Bachelor of Science degree in biology from the University of Texas and earned a master’s degree in physician assistant studies from the University of Texas Medical Branch at Galveston. Prior to joining HVC she worked in orthopedic surgery.


Kim – FNP-C

Kim received her RN certificate from The Baptist School of Health Professions in San Antonio. She earned her Master’s in Nursing as a Family Practice Nurse from The University of Miami, in Florida. Since then, she has practiced in San Antonio in emergent and urgent care settings as a Family Nurse Practitioner, until recently joining Hamilton Vein Center in San Antonio. Kim enjoys gardening and spending time with her husband and children.