Posturography Radiography , fluoroscopy and computed tomography , using X-rays Ultrasonography and echocardiography using ultrasound waves for imaging A recent advance is the substitution of invasive medical tests, such as colonoscopy by computer -based 3D reconstructions, such as virtual colonoscopy . Diagnostic signals Electrocardiography (EKG) Electroencephalography (EEG) Electromyography (EMG) Photoplethysmograph (PPG)