This retrospective cross-sectional study was approved by the institutional review board (IRB) of our institute with a waiver of the requirement for patient’s informed consent.
Population
All patients of either gender aged 30 years or above underwent CT chest,
abdomen and pelvis for different abdominal,
pelvic and urological conditions at our hospital during January 2017 to March 2017 were included whereas patients with history of trauma or road traffic accident,
already diagnosed with diffuse idiopathic skeletal hyperostosis and patients with degenerative changes/fusion of sacroiliac joints,
or with degeneration/fusion of apophyseal joints were excluded.
CT scanning technique
CT scan was performed on either of the two 16-slicer multidetector CT scan machines (Brightspeed,
GE or Somatom emotion,
Siemens).
The axial slice thickness varied from 0.75 mm to 5 mm depending upon the specific CT protocol required depending upon the clinical indication.
Also tube voltage varied between 80-120 kV and tube current between 300 to 500 mAs according to the requirements of specified protocol.
Image analysis
Following axial CT scan multiplanar reconstruction in sagittal and coronal planes was performed and sent to local Picture Archiving and Communication System (PACS).
Images were reported on workstation.
Three observers with different levels of experience evaluated all the CT scans independently and were blinded to others results.
These included one senior radiologist with more than 10 years’ experience in cross sectional imaging reporting,
a junior radiologist with more than 5 years’ experience in cross sectional imaging reporting and a radiology resident in third year of training.
The presence of DISH was based on Resnick criteria (2) on sagittal reconstruction of CT scans on bone window as: (1) Presence of flowing ossification along the anterolateral aspects of four continuous vertebral bodies (2) Intact disc spaces in the absence of gross degenerative changes of the involved vertebrae (3) Absence of fusion of apophyseal joints (4) Absence of fusion of sacroiliac joints.
Lumbar spondylosis was determined by viewing sagittal reconstruction on bone window settings of CT scan and was categorized by Kellgren-Lawrence (KL) scoring system [11] for lumbar spondylosis,
i.e.
KL 0 = normal lumbar spine,
KL 1 = tiny marginal osteophytes in the lumbar spine,
KL 2 = definite osteophytes present in lumbar spine,
KL 3 = disc space narrowing with or without osteophytes and KL 4 = End plate sclerosis,
disc space narrowing and large osteophytes.
Presence of KL2 or above was labeled as significant lumbar spondylosis.
Thoracic kyphosis angle was calculated by measuring Cobb’s angle of kyphosis on sagittal reconstruction of bone window.
The Cobb’s angle was calculated on workstation.
Cobbs angle was labeled as normal when in range of 20-40 degrees [12].
Enthesopathy was defined as a disease occurring at the sites of tendon or ligament insertion to the bone.
In the pelvis enthesopathy was checked at ischial tuberosity,
iliac crest,
greater trochanter and symphysis pubis.
The presence of atherosclerosis was based upon detection of calcification of abdominal aorta or common iliac artery.
It was graded according to criteria of grading vascular calcification [13] as follows:
Grade 0: No calcification
Grade 1: Presence of 1 or 2 non continuous calcifications without 50% circumferential involvement
Grade 2: Presence of 3 or more non-continuous calcification without 50% circumferential involvement OR one focus of calcification with 50% or more circumferential involvement
Grade 3: 2 or more non-continuous calcification with 50% or more circumferential involvement
Grade 4: 2 or more calcifications with 50% along with one area of completely concentric calcification
Grade 5: 2 or more completely concentric calcifications.
These grades was assessed at four locations as described by Kim ED et al [14] at aorta above the level of renal artery,
upper half of aorta below the renal artery,
lower half of aorta below the renal artery and common iliac artery.
The calcification grades were mentioned as calcification index (0-5) based upon the grades.
Calcification scores of 1or more was taken as positive for presence of atherosclerosis.