Transabdominal ultrasound is an excellent tool for follow-up imaging of larger cysts on or in the pancreas, although its performance falls off as surveilled known lesions decline in size, according to a study published online Aug. 1 in Abdominal Radiology.

Using same-day MRI for reference, Maryellen Sun, MD, of Lowell General Hospital in Massachusetts and colleagues, blinded to the MRI results, performed ultrasound on 57 adult patients with 252 known pancreatic cystic lesions.

The researchers measured each lesion using both modalities for transverse, antero-posterior, cranio-caudal and longest diameter views.

They also correlated visualization with physical characteristics of each patient (weight, abdominal diameter, thickness of abdominal fat, sex) and each cyst (location, size, internal complexity).

They found ultrasound nailed 100 percent of the cysts that measured 3 centimeters or larger (5 of 5) as well as 92 percent of those that measured 2 to 3 centimeters (12 of 13).

The ultrasound was good with lesions between 1 and 2 centimeters, at 78 percent (43 of 55), fair with those measuring between 5 millimeters and 1 centimeter (35 percent, or 27 of 78) and poor with those smaller than 5 millimeters (16 percent, or 16 of 101).

Meanwhile, ultrasound visualization correlated with lesion location (<0.0001), size (p < 0.0001), patient gender (p = 0.005) and participation of attending radiologist (p = 0.03), as well as inversely with patient weight (p = 0.012) and antero-posterior abdominal diameter (p = 0.01).

“Many pancreatic cystic lesions are visualized and accurately measured at follow-up with transabdominal ultrasound,” the authors conclude. “Visualization correlates with lesion size, location, patient sex, weight and abdominal diameter.”