Diffusion-weighted imaging detects GI cancer without radiation

Last Updated: 2014-12-17

By Lorraine L. Janeczko

NEW YORK (Reuters Health) - Whole-body diffusion-weighted imaging (WB-DWI) is a reliable alternative to positron emission tomography/computed tomography (PET/CT) for detecting gastrointestinal cancers without the ionizing radiation, according to new research from China.

Both PET/CT and WB-DWI accurately detect tumor recurrence and metastasis in gastrointestinal cancer. But WB-DWI costs less than PET/CT and lacks ionizing radiation, the study authors reported online November 17 in Gastroenterology Report.

"WB-DWI can detect early-stage pathological changes, especially in the area of brain and liver, and this is very encouraging. PET-CT has a high ionizing radiation, but WB-DWI can avoid the harm completely," wrote senior author Dr. Zhiyang Zhou of The Sixth Affiliated Hospital of Sun Yat-sen University in Guangzhou, China, in email to Reuters Health.

"At the same time, WB-DWI is fast, reproducible, more economical, without injected drugs, free-breathing, and also suitable for cancer screening and physical examination of healthy populations," he added.

WB-DWI may in the foreseeable future become a reliable alternative tool for staging cancer, the study authors wrote.

Dr. Zhou and colleagues compared WB-DWI to 18F-2-fluoro-2-deoxy-D-glucose PET/CT, and they also looked into the change of the apparent diffusion coefficient (ADC) between metastatic and normal tissues.

Their 28 patients (20 males, mean age 50) had stomach, esophageal, or colorectal cancer, confirmed by gastroscope or endoscopic biopsy, with suspected tumor recurrence or metastasis.

These patients, and 18 healthy volunteers, underwent WB-DWI examination with a PET/CT-based reference for comparison and were followed for 3 to 6 months. No patients received chemotherapy, radiotherapy or surgery during the study period.

Two radiologists and a nuclear medicine physician reviewed the WB-DWI and PET/CT images, and the agreement between their evaluations was measured using kappa statistics. The diagnostic accuracy, sensitivity, specificity, negative predictive value, and positive predictive value were also analyzed, and the ADC values between metastatic and normal tissues were compared.

The authors found no statistically significant differences in the overall diagnostic performances of PET/CT (accuracy 98.9%; sensitivity 95.2%; specificity 99.8%; positive predictive value 98.9%; negative predictive value 98.9%) and WB-DWI (accuracy 95.9%; sensitivity 81.7%; specificity 99.1%; positive predictive value 95.0%; negative predictive value 96.1%).

WB-DWI and PET/CT showed agreement (kappa=0.877) for detecting recurrence and distant metastasis. The difference in ADC values between the tissues of normal healthy volunteers and metastases in lymph nodes, liver and bones were significant (P<0.05).

Dr. Zhou wrote in an email that WB-DWI can be a useful tool to improve patient diagnosis and treatment and advised radiologists to "carefully interpret the data from this technology and provide clinicians and patients with information important to patient management."

SOURCE: http://bit.ly/1BZTCxe

Gastroenterol Rep 2014.