Low-Dose Ct Protocol Optimization for the Assessment of Acute Appendicitis: The Opticap Phantom Study

Abstract

ClinicalTrials.gov number, NCT01022567.

A randomised placebo-controlled double-blind multicentre trial comparing antibiotic therapy with placebo in the treatment of uncomplicated acute appendicitis: APPAC III trial study protocol

“… 31 There is accumulating evidence showing that low-dose CT protocols are as accurate as the standard protocols in diagnosing acute appendicitis, 27 34 thereby offering means to reduce the amount of ionising radiation resulting from the diagnostic CT imaging of acute appendicitis. However, we decided to use standard protocol for obese patients in the APPAC III trial, since the OPTICAP phantom trial 35 conducted by the study group endorsed the view shared by Poletti et al 43 that diagnostic accuracy of low-dose abdominal CT protocols may not yet be adequate in patients with BMI exceeding 30 kg/m 2 .…”

“…Prior to pain medication administration, pain scores using Visual Analogue Scale (VAS) will be recorded. If clinical history and physical examination suggest acute appendicitis, the patient will undergo CT imaging with either an optimised low-dose 100 kV 35 (BMI <30 kg/m 2 ) or a standard 120 kV (BMI >30 kg/m 2 ) contrast-enhanced CT. Alternatively, a corresponding low-dose protocol with automated tube voltage (kV) selection is used in all sized patients if the technique is available in the study hospitals.…”

“…Our study group conducted a prospective interpatient randomised observational study (the OPTICAP trial, NCT02533869), in which the same patient with suspected acute appendicitis underwent protocol sequence randomised consecutive imaging with both optimised standard and low-dose CT protocols with intravenous contrast media. The primary objective of the OPTICAP trial was to optimise and evaluate the feasibility of a low-dose CT protocol in diagnosing acute appendicitis in the clinical phase of the study; the protocols were first evaluated in the phantom model in ‘in vitro’ phase of the OPTICAP trial, 35 based on which a body mass index (BMI) of <30 kg/m 2 was set as a limit for low-dose CT imaging as we demonstrated additional noise to the CT caused by the adipose tissue in BMI exceeding 30 kg/m 2 potentially affecting the readability of the images. The most optimal low-dose and standard CT imaging protocols based on the OPTICAP trial were implemented in all APPAC III trial hospitals to be used for the enrolment in the current APPAC III trial and the diagnostic accuracy of contrast enhanced low-dose CT was not inferior to standard CT in diagnosing acute appendicitis or distinguishing between uncomplicated and complicated acute appendicitis in patients with high likelihood of acute appendicitis.…”

Diagnostic accuracy using low-dose versus standard radiation dose CT in suspected acute appendicitis: prospective cohort study

“…The standard-dose protocol used 120 kV, standard iterative reconstruction, and had a noise index of 12·5. The low-dose protocol used 100 kV, standard iterative reconstruction, and had a noise index of 14·5 29 , 30 . The dose length product (DLP) for each CT examination was registered.…”

“…This may be due to a lack of comprehensive data on the accuracy of these low-dose protocols in assessing the severity of appendicitis. The OPTICAP study assessed this clinically important topic, first by optimizing the imaging in vitro 29 , followed by a prospective interpatient randomized study 30 ; the latter enrolled 60 patients with a BMI under 30 kg/m 2 and suspected acute appendicitis undergoing consecutive low- and standard-dose imaging. The low-dose CT was shown to be non-inferior to standard-dose CT in terms of accuracy both in diagnosing appendicitis and non-appendicitis, as well as in differentiating between uncomplicated and complicated acute appendicitis.…”