Study: Digital tomo improves accuracy, lowers rad dose for pulmonary lesions
Digital tomosynthesis can improve diagnostic accuracy and confidence of suspected pulmonary lesions on chest radiography, according to a study published online June 30 in Academic Radiology.
“The detection and characterization of pulmonary lesions, particularly of pulmonary nodules, are challenging tasks in thoracic imaging because of their frequently small size and poor conspicuity within surrounding anatomic structures,” explained Emilio Quaia and colleagues from the departments of radiology and medical physics at Cattinara Hospital in Trieste, Italy. They noted that while CT is the “gold standard” for imaging pulmonary lesions, it is expensive and delivers considerable radiation dose to patients.
The authors conducted their study to evaluate digital tomosynthesis, a technique similar to CT but with a lower radiation dose and can be implemented in conjunction with chest radiography because it uses the same x-ray equipment.
From January 2008 to January of this year, the prospective study recruited 228 patients (133 men) with an average age of 70.8 years presenting with suspected pulmonary lesions. After an initial analysis via chest radiography, each patient underwent digital tomosynthesis. One independent reading radiologist with three years of experience and one with 20 years of experience prospectively analyzed the chest radiographic and digital tomosynthesis images on a PACS workstation and offered a diagnostic confidence score for each lesion (one or two = definitely or probably extrapulmonary lesion or pseudolesion, three = indeterminate, four or five = probably or definitely pulmonary lesion). The researchers utilized chest CT exams as a basis for comparison.
The researchers determined that a total of 251 suspected pulmonary lesions were identified. Both digital tomosynthesis and CT did not confirm any lesion in 71 patients and in the remaining 157 patients, 180 lesions were identified, including 112 pulmonary and 68 extrapulmonary lesions.
“In 110 reader one [detected lesions by the first reading radiologist with three years experience] and 123 reader two lesions, correct diagnoses were provided after analysis of the chest radiographs. All lesions were correctly classified after digital tomosynthesis except for 14 extrapulmonary lesions (both readers) that were misinterpreted as pulmonary and 10 reader one and six reader two pulmonary lesions that were misinterpreted as pleural,” the authors offered.
Accuracy also was found to differ between modalities and between the readers, the authors found. For digital radiography, reader one scored a 43 percent accuracy rating, while reader two scored 49 percent. For digital tomosynthesis, reader one scored 90 percent and reader two scored 92 percent.
“In comparison to chest radiography, digital tomosynthesis produces superior images for identifying the intrapulmonary or extrapulmonary locations of suspected pulmonary lesions previously identified or suspected on the basis of chest radiographic interpretation,” explained Quaia and colleagues.
Noting that tomosynthesis is an imaging technique that offers a lower cost than both CT and MRI, “digital tomosynthesis may offer an improvement over conventional radiography at a lower radiation dose than CT,” concluded the researchers.
“The detection and characterization of pulmonary lesions, particularly of pulmonary nodules, are challenging tasks in thoracic imaging because of their frequently small size and poor conspicuity within surrounding anatomic structures,” explained Emilio Quaia and colleagues from the departments of radiology and medical physics at Cattinara Hospital in Trieste, Italy. They noted that while CT is the “gold standard” for imaging pulmonary lesions, it is expensive and delivers considerable radiation dose to patients.
The authors conducted their study to evaluate digital tomosynthesis, a technique similar to CT but with a lower radiation dose and can be implemented in conjunction with chest radiography because it uses the same x-ray equipment.
From January 2008 to January of this year, the prospective study recruited 228 patients (133 men) with an average age of 70.8 years presenting with suspected pulmonary lesions. After an initial analysis via chest radiography, each patient underwent digital tomosynthesis. One independent reading radiologist with three years of experience and one with 20 years of experience prospectively analyzed the chest radiographic and digital tomosynthesis images on a PACS workstation and offered a diagnostic confidence score for each lesion (one or two = definitely or probably extrapulmonary lesion or pseudolesion, three = indeterminate, four or five = probably or definitely pulmonary lesion). The researchers utilized chest CT exams as a basis for comparison.
The researchers determined that a total of 251 suspected pulmonary lesions were identified. Both digital tomosynthesis and CT did not confirm any lesion in 71 patients and in the remaining 157 patients, 180 lesions were identified, including 112 pulmonary and 68 extrapulmonary lesions.
“In 110 reader one [detected lesions by the first reading radiologist with three years experience] and 123 reader two lesions, correct diagnoses were provided after analysis of the chest radiographs. All lesions were correctly classified after digital tomosynthesis except for 14 extrapulmonary lesions (both readers) that were misinterpreted as pulmonary and 10 reader one and six reader two pulmonary lesions that were misinterpreted as pleural,” the authors offered.
Accuracy also was found to differ between modalities and between the readers, the authors found. For digital radiography, reader one scored a 43 percent accuracy rating, while reader two scored 49 percent. For digital tomosynthesis, reader one scored 90 percent and reader two scored 92 percent.
“In comparison to chest radiography, digital tomosynthesis produces superior images for identifying the intrapulmonary or extrapulmonary locations of suspected pulmonary lesions previously identified or suspected on the basis of chest radiographic interpretation,” explained Quaia and colleagues.
Noting that tomosynthesis is an imaging technique that offers a lower cost than both CT and MRI, “digital tomosynthesis may offer an improvement over conventional radiography at a lower radiation dose than CT,” concluded the researchers.