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           1a            1b          1c

2a 2b 2c 2d

Virtual Colonoscopy (VC) is a new method that allows 3-D visualization of the large bowel (colon) to detect polyps and cancers. Polyps are small growths in the colon that may become cancerous if they are not removed. Virtual Colonoscopy is a recently developed technique that uses a fast multi-slice helical CT scanner (MSCT) and computer 3D virtual reality software to look inside the bowel lumen without having to insert a long scope (Conventional Colonoscopy) or having to fill the colon with liquid barium (Barium Enema).

Patients need a cleansing preparation of their bowel prior to the test. The actual VC procedure will begin by having a small flexible rubber tube placed in the rectum, so that air can be introduced. A helical CT scan is then performed while the patient lies comfortably on the back (supine) and then on the stomach (prone). The total time required for the study is around 15 minutes. Because sedation is not required, patients are free to leave the CT suite immediately without the need for observation or recovery. Patients can resume normal activities immediately after the procedure and can eat, work or drive without a delay. When air is introduced in the colon, some patients experience minimal temporary abdominal cramping or "gas pains."


Research has shown that Virtual Colonoscopy is better able to see polyps than Barium Enema and is nearly as accurate as Conventional Colonoscopy. Fig. 1 shows a polyp and Fig. 2 a flat cancer seen on 3 techniques: 2D axial CT (Fig. 1a, 2a-b), 3D VC (Fig. 1b, 2c), and conventional colonoscopy (Fig. 1c, 2d). Most patients report that the Virtual Colonoscopy technique is more comfortable than either Barium Enema or Conventional Colonoscopy. Studies suggest a very high sensitivity and specificity (96%) for the detection of polyps 1 cm or greater. Such polyps have significant malignant potential. Sensitivity for polyps less than 1 cm is significantly less. Although controversy exists as to the definition of a "significant" polyp with regard to size, polyps < 1 cm in size have a low probability of malignancy and the likelihood of any single lesion progressing to cancer is also small.


Indications for VC include screening for polyps, incomplete or failed colonoscopy, and preoperative assessment of the colon proximal to an occlusive cancer (defined as a tumor that cannot be traversed endoscopically). Virtual colonoscopy excels in the evaluation of the ascending colon, particularly the cecum due to the degree of distension achievable and the typical lack of spasm or muscular hypertrophy, which is seen in the sigmoid colon. It is therefore a useful complement to an incomplete colonoscopy. Any questionable abnormality will warrant a conventional colonoscopy procedure, thus resulting in GI referrals.

VC may become a screening tool for detecting colorectal neoplasia, potentially supplanting Conventional Colonoscopy as a tool for detecting lesions. Increased screening, with increased detection, should decrease the incidence of colorectal cancer, as premalignant growths can be found at an earlier stage. About 5% of colon cancers (flat cancers) arise from normal mucosa and not from polyps and are difficult to identify on conventional and virtual colonoscopy, while axial helical CT images improve detection of such cancers.

HealthScan Program

AIC has been offering for some time a screening total-body scan program called HealthScan, which includes a screening helical CT of the torso, helical CT coronary calcium scoring, and more optional 3D virtual colonoscopy.


Facts about services at AIC

1.     The only community-based, private-practice, physician-operated imaging facility in the Antelope Valley, just like any other private practice medical office.   Not belonging to any hospital or outside imaging network.   This means more personal and caring service.

2.     AIC was the first MRI-accredited site in the Antelope Valley ... approved by the American College of Radiology's MRI Accreditation Committee.

3.     Dr. Ray Hashemi is the only radiologist in the area with fellowship training in ALL aspects of MRI, including neuro and musculoskeletal MRI.


Why is AIC the PIONEER in advanced medical imaging in the Antelope Valley?

1.     AIC was the first to introduce a high-quality OPEN MRI (open-air or open-sided MRI) to the Antelope Valley (January 1998).

2.     AIC was the first to introduce Short-bore OPEN High-Field (1.5 Tesla) MRI to the Antelope Valley (January 1999).

3.    AIC was the first to introduce multi-slice CT (MSCT) to the Antelope Valley (August 1999); upgraded to a 16-slice CT in 2003.

4.     AIC was the first to introduce revolutionary 3D Ultrasound to the Antelope Valley (April 1999); upgraded to a GE 4D Ultrasound in 2004.

5.     AIC was the first to introduce a PET scanner to the Antelope Valley (July 1999).

6.     AIC was the first to achieve MRI Accreditation in the Antelope Valley (July 2000).

Call us at one of our three locations: Lancaster (661) 949-8111, Palmdale (661) 456-2020 or Valencia (661) 255-0060

copyright 2004 ray h. hashemi, m.d., ph.d.