This was a prospective single-centre observational (case-control)study.
Patients
70 asymptomatic type-2 DM patients were enrolled:
- 34 with CN;
- 36 with DN without CN.
All subjects had a DN diagnosis according to the standardized procedure of Ewing and Clarke [11-12]. All CN patients had previous X-rays (and MR in some cases) of both feet taken during the acute phase to confirm or rule out CN diagnosis [13]. None of the subjects had a history of ulceration,
and the CN group did not include individuals in the acute phase at the moment of study.
All patients did not have cardiac symptoms and showed a normal physical examination and ECG at rest. Exclusion criteria included a history of known CAD, smoking history (to avoid the possible confounding role of this risk factor), New York Heart Association (NYHA) class III-IV,
absence of sinus rhythm,
heart rate (HR) >75 beats per minute (bpm) despite beta-blocker treatment,
inability to lie flat or keep an adequate breath-hold,
allergy to iodine contrast material (CM),
and recent (<30 days) creatinine value >1.5 mg/dL (>132 μmol/L). The following RFs for CAD were assessed: systemic hypertension, hypercholesterolemia, obesity,
microalbuminuria,
and family history of CAD (Table 1).
MDCT
Imaging was performed in all cases with a 64-row scanner (Lightspeed VCT; General Electric,
Milwaukee,
Wi,
USA), during a single inspiratory breath-hold per acquisition.
Calcium Score
- CACS was obtained with unenhanced prospective ECG-gated cranio-caudal sequential MDCT (main parameters: slice thickness 2.5 mm, default acquisition at 70% of the R-R interval).
- CS was evaluated with the same protocol,
without ECG-gating, in the neck (carotid bifurcations) and in the distal thirds of the calf/feet (distal anterior and posterior tibial,
peroneal,
dorsal,
and plantar arteries).
Scan data was transferred to an off-line workstation for post-processing, performed by a dedicated software to calculate the Agatston score (AS) for the three different anatomic districts, distinguishing four different categories: low (<200 AS), mild (200-299),
moderate (300-399), and severe (>400) [14].
MDCT-CA
- MDCT-CA was performed with a retrospective ECG-gated cranio-caudal helical scan with ECG-controlled tube current modulation (ECG-pulsing),
and with intravenous administration of CM (400 mgI/mL, 80 mL,
5 mL/s) followed by a saline chaser (60 mL,
5 mL/s) through an automated double-head injector (main parameters: slice thickness 0.625 mm,
acquisition start delay established by monitoring the aortic enhancement with a bolus-tracking technique involving a region of interest (ROI) placed in the ascending thoracic aorta).
Scan data was reconstructed using a monosegmental algorithm,
with a first reconstruction dataset fixed at 75% of the R-R interval; if needed, further reconstructions were performed at different cardiac phases (usually from 40% to 80% of the R-R interval),
and dedicated high spatial resolution reconstruction filters were used to reduce calcium-related blooming artifacts. All reconstructed datasets were transferred to an off-line workstation for post-processing,
performed by a dedicated software to obtain both 2-dimensional (multi-planar reformation,
MPR and maximum intensity projection,
MIP) and 3-dimensional (volume rendering,
VR) reconstructions.
A single reader, expert in MDCT-cardiac imaging,
assessed all exams,
considering a threshold of maximal luminal diameter reduction >50% for significant coronary stenosis diagnostic of CAD,
and using the American Heart Association (AHA) classification for coronary artery segmentation [15-16] (Fig.
1a-d).
Invasive CA
Invasive CA was performed within 2 weeks in cases with a diagnosis of significant coronary stenosis at MDCT-CA by a single experienced cardiologist blinded to the MDCT-CA findings, both as diagnostic standard reference and,
if needed,
as treatment (Fig.
1e-f).
Coronary lesions were examined in orthogonal views and stenosis severity quantitatively determined using an automated edge detection system (quantitative CA,
QCA).
Statiscal Analysis
Continuous variables were expressed as mean ± standard deviation (SD); categorical variables were displayed as frequencies. All data was first analyzed for normality of distribution using the Kolmogorov-Smirnov test. The Mann-Whitney U test was used for non-normally distributed continuous variables and the t test for normally distributed variables.
Categorical variables were compared using the χ2 test.
Correlations were calculated with the Spearman’s correlation coefficient.