Florence Benjamin lay on a stretcher in the MRI room at the Royal Victoria Hospital as a radiology technologist prepared her for a scan.

"What radio station would you like to listen to?" asked Denise Blanchette.

"CFQR," Benjamin replied, shifting her body to make herself more comfortable.

Blanchette covered Benjamin with a blanket, left the room and closed the door behind her. In the control room, she switched the FM radio to Benjamin's favourite light-rock station. Every Breath You Take, by The Police, came on.

Blanchette sat down in front of a computerized console. The stretcher slid into the hole of the giant, doughnut-shaped magnetic resonance imaging machine. Only the top of Benjamin's head was visible.

For the next 45 minutes, Blanchette and Mohan Patel, the co-ordinator of the MRI room, would be scanning the soft tissues inside Benjamin's body using the latest in three-dimensional medical imaging technology.

They would be taking images of Benjamin's uterus, checking for fibroids, which are benign tumours.

Medical imaging has come a long way since the X-ray was discovered in 1895 by Wilhelm Conrad Roentgen, a German physics professor. X-rays are still widely used today, but they don't take good images of tissue, hence the need for other imaging technologies like MRI and positron emission tomography.

X-ray images show only two dimensions of space: length and width. That might be fine to show a leg fracture, but radiologists often need to look at images in all three dimensions to make better diagnoses.

Computed tomography, developed in the early 1970s, was the solution. Many X-ray "slices" are taken of an area of the body to provide the third dimension of depth. The X-ray slices are combined to construct a 3-D image.

Back to Benjamin, who was relaxed and breathing normally inside the $2.2-million MRI machine. An MRI camera uses electromagnetic fields and radio frequencies rather than X-rays. For an X-ray, a patient must not move. For an MRI scan, a patient must not move and be careful not to breathe erratically, otherwise the images of the tissue and organs become skewed.

Under Blanchette's guidance, the MRI machine took three scans of Benjamin's body. The first scan was on the coronal or frontal plane. The machine buzzed loudly, taking 20 image slices.

The second scan was on the sagittal plane, from one side of the body to the other. The third scan, on the axial plane, was taken from the top of Benjamin's torso to the bottom.

The computer screen showed three images: frontal, side-to-side and top-to-bottom. A radiologist would later examine them in a 3-D reconstruction.

Sitting next to Blanchette, Patel explained the advantages of 3-D imaging technology. He pointed to another computer screen that displayed ghost-like images of the inside of the body of an elderly man suffering from artery disease.

A frontal image showed what appeared to be a healthy abdominal aorta. But Patel then spun the image on the screen to reveal the side of the body. The artery suddenly looked jagged, clear evidence of arteriosclerosis. The blood supply to the man's legs was being choked off by the hardening aorta and more images showed that the arteries in his legs were clogged as well.

No wonder the man had found it painful to walk.

"Abnormalities can be missed if you can't see all the angles," Patel said.

By making the proper diagnosis, doctors could pinpoint the exact spots where the man's leg arteries had hardened and would be able to perform graft surgery to restore proper blood flow.

Larry Stein, chief of radiology at the Royal Vic, said his specialty has probably benefited from more technological advances than any other field of medicine.

"Back in the early '70s, I was doing an ultrasound and trying to convince people that what I was looking at was actually the gallbladder - the images were so rough," he recounted.

"Today, there's CT, MRI and PET scanning and all the interventional radiology."

Radiologists like Stein no longer only make diagnoses. The technology has advanced to the point where they can intervene in the body, blocking aneurysms in the brain or opening a narrowed artery with a balloon angioplasty. None of this could be achieved without being able to view the inside of the body in three dimensions.

But medicine is not content with the three dimensions; it's pushing beyond to the fourth and even a fifth dimension.

As any physicist will tell you, there are four dimensions, three spatial and one involving time. Hence, the concept of space-time. Four-D medical imaging allows clinicians to view 3-D images of a fetus as it moves in the uterus in real time. Four-D imaging is also useful to evaluate a beating heart for coronary artery disease.

The fifth dimension, for medical purposes, is like a second dimension of time. Three-D images are shown moving in the fourth dimension, and the fifth dimension adds artificial colors to depict specific functions of an organ.

Five-D imaging, however, is far from the norm today.

Benjamin's scan was over. If Blanchette or Patel saw something abnormal, they didn't share it with the patient. They would confer with the radiologist.

Still, she walked out of the MRI room smiling.