Patient Selection
Patients >18 y.o.
with known endoscopic or pathological diagnosis of CD who underwent to CTE between February and November 2018 with a 3rd generation dual Source DECT (dsDECT) were included.
Patients with contraindication to iodinated contrast material or with lack of clinical or pathological documentation were excluded.
CTE Scan Protocol
A water solution of polyethylene glycol was administered to all patients before CTE (Macrogol,
Macro P,
Alfasigma,
Milan,
Italy).
All patients also received a spasmolytic agent (Hyoscine Butylbromide,
20 mg iv,
Buscopan,
Boehringer Ingelheim,
Barcelona,
Spain).
Patients were scanned with a 3rd generation dsDECT (Somatom Force,
Siemens Healthineers,
Erlangen,
Germany).
A pre-contrast acquisition was obtained with the following parameters: 120 kVp,
modulated mA,
rotation time 0.5 s,
Pitch 0.6,
iterative reconstruction ADMIRE (Siemens Healthineers,
Erlangen,
Germany) strength 3,
Kernel Br40,
slice thickness/spacing: 2/1 mm.
The enterographic phase was acquired at 45-55 s after 1 ml/kg body weight of Iopamidol 370 mgI/mL (Iopamiro 370,
Bracco,
Milan,
Italy) at 2.5 – 4 mL/s).
The technical parameters were the following: 100/Sn150 kVp,
modulated mA,
rotation time 0.5 s,
Pitch 0.6,
iterative reconstruction ADMIRE (Siemens Healthineers,
Erlangen,
Germany) strength 3,
Kernel Qr40,
slice thickness/spacing: 2/1 mm.
Post Processing and Image Evaluation
The image analysis and DECT Datasets post-processing were performed on dedicated consolle (Syngo.via Frontier,
Siemens Healthineers,
Erlangen,
Germany),
and VNC were calculated with a 3-material decomposition algorithm (Liver VNC; Siemens Healthineers,
Erlangen,
Germany).
Two radiologists with 10 and 5 years of experience in gastrointestinal imaging in consensus evaluated the image quality on TNC and VNC with a semi-quantitative 5-point scale (1: non-diagnostic; 5: optimal quality).
Quantitative analysis was performed by placing circular regions of interest (ROI) in intestinal wall and perivisceral fat at different levels: involved segment,
proximal jejunum,
jejuno-ileal,
distal ileum,
respectively in left hypochondrium,
mesogastrium,
and right iliac fossa – pelvis.
Mean attenuation in HU and standard deviations (SD) were recorded for bowel wall,
lumen,
and perivisceral fat (Figure 1).
The signal-To-Noise ratio (SNR) was calculated as HUwall/SDwall and Contrast-to-noise ratio (CNR) as (HUwall-HUfat)/SDfat.
Statistical Analysis
Statistical analysis was performed with MedCalc software v12.5 (MedCalc Software,
Ostend,
Belgium).
Quantitative variables were expressed as median and interquartile range.
Differences between mean attenuation (HU) of bowel wall,
lumen,
and perivisceral fat between VNC and 120 kVp TNC were calculated.
Non-parametric tests were used.
Significant p was set at p<0.05.