(4) Radiopaque markers may be taped to the patient's body (or to the grid)
to indicate anatomical relationships or landmarks. In any case, at least one of the
radiographs out of each group (exposed at right angles to each other) should provide
sufficient coverage to facilitate positive identification of the pertinent relationships
between the position of the lumbar-puncture needle, the contrast medium situated in the
spinal canal, and the important anatomical landmarks.
f. Technique in Which a Relatively Large Amount (6 to 21 cc) of Contrast
Medium is Used. This is sometimes referred to as "full-column myelography," erect-
method myelography," or "total myelography."
(1) Upon completion of the preliminary phases of the procedure, the patient
is adjusted in a lateral recumbent position on the tilt-table unit. The spinal-puncture
needle is inserted, a cerebrospinal pressure reading is recorded, and cerebrospinal fluid
is collected for laboratory analysis.
(2) The head-end of the table is now raised approximately 10 to 20 degrees
from the horizontal. The contrast medium is injected into the subarachnoid space in the
lumbar region after withdrawal of a similar amount of cerebrospinal fluid. The lumbar-
puncture needle is then removed and the patient is adjusted in the same position with
his feet placed firmly against the footrest.
(3) After properly alerting the patient, the table is brought into the vertical
relationship. Additional fluoroscopy, spot-filming, or radiography is carried out
according to the directions of the examiner. The table is then returned to the horizontal
relationship and the patient lies in the supine position. Further fluoroscopic and
radiographic studies may be carried out, if indicated.
(4) Upon completion of the examination, the spinal-puncture needle is
reinserted for subsequent removal of the contrast medium.
g. Thoracic Myelography.
(1) Patient prone. The patient is placed in the prone position on the tilt-table
unit with the head fully extended. Some examiners may prefer to elevate the lower
back by placing a suitable bolster under the lower abdominal region. The contrast
medium and the manner of its introduction are essentially the same as in lumbar
myelograph. In some instances, however, the contrast medium may have to be
injected. Under fluoroscopic control and by slowly lowering the head-end of the table,
the column of radiopaque control medium is made to flow into the subarachnoid space
of the thoracic spine. Spot-films are taken in various positions as indicated.
Conventional radiographic technique may be used for the sagittal and lateral
projections. With the lateral projection, a horizontal CR is preferred.