The Advantages of Image-Guided Modalities for Physicians, Patients

How image guidance is the intervention game-changer in healthcare

One of the greatest technological revolutions in medicine is imaging, which gives us the nonsurgical ability to see structures and disorders within the body. As imaging has evolved and progressed through X-rays, ultrasound, nuclear medicine scans and multiparametric MRI, there have been enormous strides in the safety and resolution of diagnostic scans. Aided by sophisticated software and improved power, imaging renders breathtakingly minute details of internal systems.

Today, the noninvasive detection and diagnosis of disease conditions is an efficient and painless process that provides an intimate “portrait” of a patient’s condition. As a result, doctors can educate their patients about the nature of their disease, discuss options, and prioritize treatment decisions.

There is more to imaging than identification of problems. What is happening is a virtual revolution in treatment due to curative interventions using minimal-to-noninvasive tissue ablation performed under real-time image guidance. With ever-widening applications, ablation has become a viable alternative to surgery, radiation and pharmaceutical management.

Not only are image-guided modalities gaining traction among physicians, but their expansion is also driven by patient demand. Internet discussion forums reveal burgeoning online dialogue among savvy men and women who are conversant with concepts like “tissue sparing treatments” or “treat and monitor.” They actively seek out such interventions for benign and malignant conditions alike because, in addition to a reasonable shot at competitive disease control, they also want:

  • Little, if any, down time from work, family and social activities
  • Little to no impact on self-image and self esteem
  • Preservation of healthy tissue functions with few to no side effects

Thus, the appeal of image-guided treatments lies in their ability to give patients what they want. Two examples, one in women’s health and one in men’s health, illustrate their benefits.

MRI-Guided Focused Ultrasound (FUS) for Uterine Fibroids

Uterine fibroids hamper a woman’s health and lifestyle. It is estimated that over 70% of women have these noncancerous growths, and about 25% of them experience pelvic pain, menstrual problems, change in urinary habits or difficulty getting pregnant. If symptoms become severe enough to warrant treatment, surgery is still considered the gold standard.

Many women, however, want to avoid its difficulties and risks, including infertility. Alternatives to surgery already include minimally invasive treatments (uterine artery embolization or UAE, cryotherapy, laser ablation, radiofrequency ablation) that can be done under image guidance. Now there is also a completely noninvasive treatment called Magnetic Resonance-guided Focused Ultrasound (MRgFUS) that avoids the risks associated with penetrating tissue. It uses ultrasound waves that pass harmlessly through intervening tissues until they are pinpointed upon their target, where the heat effect creates necrosis.

Image-guided FUS is used for a range of conditions, such as prostate cancer and glaucoma to Parkinson’s disease-related tremors and others. The Food & Drug Administration approved MRgFUS as a thermal ablation modality for uterine fibroids in 2004, noting that the device used to administer MRgFUS is the first time that two systems have been combined:

  1. A focused ultrasound beam that heats and destroys the uterine fibroid tissue using high-frequency, high-energy sound waves
  2. A magnetic resonance imaging (MRI) and thermal mapping system to visualize patient anatomy, map the volume of fibroid tissue to be treated, and monitor the temperature of the uterine tissue after heating

Clinical studies suggest that symptom relief for most women accrues over time. According to one paper, “88% reported a 10-point or greater symptom improvement at 6 months, and 91% had significant symptom improvement at 12 months.”

The procedure is done on an outpatient basis with the patient lying prone on a table that slides into the bore of the magnet, and averages about three hours. This includes the MRI mapping time. Medication is used for relaxation, but there is no general anesthesia as the patient must be able to communicate and follow instructions. Recovery is rapid and patients quickly resume normal routines. Of key importance for women who want to preserve the option of pregnancy, MRgFUS spares the uterus and ovaries. It is no wonder that women with troubling fibroids are increasingly excited about this option.

Image-Guided Focal Prostate Cancer Ablation

In men’s health, a similar phenomenon to image-guided fibroid ablation has been developing since the mid-1990s. Focal prostate cancer treatment is aimed at destroying prostate cancer tumors while preserving healthy tissue, urinary and sexual function. The rapid evolution of this approach has occurred in response to the recognition that roughly one-third of prostate cancers have one or more characteristics that make them amenable to a targeted treatment: localization within the gland, unifocality, and lack of cellular aggressiveness.

Prostate cancer patients with such low-risk disease find focal therapies attractive because they constitute a middle ground between radical treatments (surgery, radiation) that place urinary and sexual function at risk vs. active surveillance that carries a psychological burden of anxiety and uncertainty. Focal treatment has the added benefit of keeping all future treatment options open, including a repeat ablation, should localized cancer recur.

The earliest successful focal treatment of prostate cancer was performed using ultrasound-guided cryoablation (freezing), and the earliest published literature was primarily case studies or small series of patients who had been treated this way. Medicare approval for whole-gland cryoablation was granted in 1999, and for salvage whole-gland treatment (for radiation recurrent disease) in 2001. Although focal cryoablation was considered an off-label application, a gradual increase in the number of radiologists and urologists who offered it, and patients who sought it, continued as the concept of a truly focal prostate cancer treatment took hold.

Since the new millennium, other image-guided thermal ablation technologies have been adapted from whole-gland ablation or developed specifically for focal ablation:

  • Ultrasound-guided HIFU (high-intensity focused ultrasound), which uses a transrectal probe to deliver the treatment
  • MRI-guided LITT (laser-induced interstitial thermal ablation) or simply FLA (focal laser ablation) which uses a laser optic fiber to generate an ablation zone that can be tracked and confirmed using MRI thermography
  • Ultrasound- or CT-guided IRE (irreversible electroporation) which delivers an electrical current that selectively destroys cancer cells
  • Ultrasound-guided PDT (photodynamic therapy) which relies upon an IV-administered photosensitizing agent taken up by cancer cells, and probes to deliver a light source that activates the agent to produce toxins within the cells
  • MRI-guided cryoablation

Similar to what is occurring in women’s health, image-guided treatments that benefit prostate cancer patients continue to evolve in safety, effectiveness and popularity. From their perspective, their cancer has been controlled and they are back to normal life in practically no time at all.

The Future

Ongoing advances in imaging parallel developments in treatment technologies. MRI is perhaps the greatest game-changer due to its high resolution images that involve no radiation exposure, and the increasing availability of MRI-compatible ablation technologies from device manufacturers. Regardless of the type of scan or treatment device, image-guided treatments are fulfilling their promise to patients.

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