Improving osteoporotic vertebral deformity detection on chest frontal view radiograph by adjusted X-ray beam positioning

Abstract

Purpose: In clinics, chest frontal view radiograph (CFR) is often taken for patients suspected of respiratory diseases and for assessing the heart and big vessels. CFR can be utilised to opportunistically detect osteoporotic vertebral fracture (OVF). However, for standard CFR, the site of highest OVF prevalence, i.e., the thoracolumbar junction, is usually 'off-centre' to the X-ray beam focus. This study tested the hypothesis that, if a CRF is taken with approximately two vertebrae lower than the standard X-ray beam positioning, the visualization of thoraco-lumbar junction can be much improved.

Materials: Four hospitals (A, B, C, D) provided 101 elderly women's digital CFRs with standard filming (28, 20, 24, and 21 cases respectively). Eighty four elderly female patients were prospectively recruited from hospitals-A and B, who were consecutive patients referred for chest radiograph with indications other than spine disorders. For theses prospective CFRs, the focus of X-ray beam was adjusted from towards vertebra T6 to towards T8, and standard lateral radiographs were obtained for reference. Visibility of spine and detectability of OVF were assessed on the CFRs. OVF was diagnosed based on chest lateral radiograph (CLR) after excluding other potential causes both radiographically and clinically.

Results: For standardly filmed CFR, spine readability was similar among those from Hospitals-A, B, and C, while performed less well for those from Hospital-D. With the prospective cases from Hospitals-A and B, spines readable to vertebra L1 level or lower increased from 48.2% for standard filming to 80.7% for adjusted filming. Spines with 'blurry' labelling decreased from 35.7% for standard filming to 15.7% for adjusted filming. For the 84 prospective cases, 42.9% (36/84) of the patients had OVF, and 26 cases of CLR positive cases were detected as having vertebral deformity on CFR. For minimal OVF cases (<20% height loss), 38% (5/13) were detected on CFR. Among 22 cases with apparent OVF (≥20% height loss), two cases were missed on CFR. False positivity was labelled in five cases, among them four cases had 'burry' spines.

Conclusion: CFR can help opportunistically detect OVF, which can be further improved if X-ray beam is adjusted to towards vertebra T8 instead of towards vertebra T6.

The translational potential of this article: This study confirms that CFR can help detect OVF opportunistically, and the visibility of the mid/lower thoracic spine and thoracolumbar junction can be much improved after minor adjustment of X-ray beam positioning. This study also suggests high positive rate of OVF in elderly Chinese female patients indicated for chest radiograph. Radiologists should be trained and sensitized in vertebral deformity identification on CFR as the clinical management can be improved by opportunistic detection of OVF.

Keywords: Chest; Frontal view; Osteoporosis; Radiograph; Vertebral deformity; Vertebral fracture.

Fig. 1

Abdominal radiograph of a 70-year-old female patient. A renal stone and urinary drainage catheter are noted on the right side. Arrow indicates L1 apparent vertebra deformity.

Fig. 2

Chest frontal view radiographs taken with standard X-ray beam positioning may show blurry thoraco-lumbar junction, while radiographs taken with X-ray beam approximately two vertebrae lower than the standard positioning improve the visualization of thoraco-lumbar junction. A: chest frontal radiograph (brightness and contrast adjusted for viewing the spine) of a female patient of 72 years old taken according to standard positioning of X-ray beam, with the thoraco-lumbar junction poorly demonstrated for this case (A1). Lateral chest radiograph (A2) shows T12 and L1 minimal deformity (blue arrows), which cannot be evaluated on A1 (blue arrows). On frontal radiograph (A1), blurry appearance of thoraco-lumbar junction may be mis-labelled as with vertebral deformity. The shapes of L2 and L3 (yellow arrows) are distorted due to the X-ray projection. B: chest radiographs (B1: frontal view, brightness and contrast adjusted for viewing the spine; B2: lateral view) of another female patient of 72 years old taken according to the adjusted X-ray beam (two vertebrae lower than the standard positioning). The vertebrae at thoraco-lumbar junction are well demonstrated till L2 on (B1). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 3

A diagram of shifting the beam of X-ray downward for approximately two vertebrae. Blue thin lines indicate the standard X-ray beam with focus towards T6 vertebra. Yellow thin lines indicate the adjusted X-ray beam with focus towards T8 vertebra. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)

Fig. 4

A female patient of 83 years old. Left: standard filming (brightness and contrast adjusted for viewing the spine) shows slight blurry of T12, L1 and L2. Right: filming with adjusted X-ray beam positioning better shows T12-L3 for the same patient.

Fig. 5

Frontal view radiograph of a female patient of 71 years old with adjusted filming (brightness and contrast adjusted for viewing the spine). Despite the apparent obesity of this subject, the spine is well demonstrated.

Fig. 6

Frontal view radiographs of the patient of Fig. 2B (A) and the patient of Fig. 4 (B), with brightness and contrast of the radiographs adjusted for viewing the lungs.

Fig. 7

A female patient of 66 years old. L1 apparent vertebral deformity was detected on frontal radiograph (arrow, A; brightness and contrast adjusted for viewing the spine), which is confirmed on lateral radiograph (arrow, B).

Fig. 8

A female patient of 77 years old. L1 apparent vertebral deformity was detected on frontal radiograph (arrow, A; brightness and contrast adjusted for viewing the spine), which is confirmed on lateral radiograph (arrow, B). C shows an image magnified around L1 which demonstrates apparent depression of upper endplate.

Fig. 9

A female patient of 72 years old. Frontal view radiograph (brightness and contrast adjusted for viewing the spine) shows T12 deformity (arrow), which is confirmed on lateral view radiograph as apparent deformity (arrow).

Fig. 10

A female patient of 66 years old. L1 minimal deformity can be identified on lateral view radiograph (arrow), which was missed during fontal view radiograph reading (brightness and contrast adjusted for viewing the spine, arrow indicating lower endplate blurry).

Fig. 11

A female patient of 70 years old. L1 minimal deformity can be identified on lateral view radiograph (arrow), which was false negative on fontal view radiograph (brightness and contrast adjusted for viewing the spine).

Fig. 12

A female patient of 66 years old. T7 vertebral deformity (arrow) was initially missed during frontal view radiograph reading (brightness and contrast adjusted for viewing the spine). Lateral view radiograph shows T7 apparent deformity (arrow).

Fig. 13

A female patient of 76 years old. T5 apparent deformity (arrow) is shown on lateral view radiograph but cannot be diagnosed on frontal view radiograph. Lower thoracic spine and thoracolumbar junction vertebrae are not well demonstrated on frontal view radiograph (brightness and contrast adjusted for viewing the spine), and in this case vertebrae at thoracolumbar junction can be miss-labelled as with deformity. For the thoracolumbar junction region, lateral view radiograph shows oblique projection of X-ray beam (yellow lines) relative to spine axis (dotted orange line). Green line: X-ray detector. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)