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Trauma
1.
I am developing a whole body, vertex to pubis, protocol for severely
traumatized patients on a Philips MX8000 (Quad) MDCT. I am aware of
MGH and UT Houston protocols for GE lightspeed QX/I MDCT based on 5
mm slice thickness. On the MX8000, I am concerned 6.5 slice thickness
for the thoracic aorta is too thick to allow 3D VR, but for the abdomen,
3.2 slice thickness is too thin. If we need MPRs of the thoracic and
lumbar spine, 6.5 mm is too thick. Even with a 4 channel scanner, scanning
the head and c-spine, then doing 3.2s of the C/A/P is challenging to
the tube, and generates over a thousand images. Can you direct me to
any literature on MX8000 protocols for blunt trauma whole body CT?
| Answer:
Call Phillips directly, and ask for Irene. She usually has the Phillips
answers. Remember that even 3 mm is not optimal if detailed MPR's
or 3D's are done. |
2.
What is the best CT protocol to demonstrate vascular damage to the kidneys?
For a trauma patients with retroperitoneal bleed, in order to determine
if renal perfusion was adequate (i.e. active bleeding). Literature (Harris,
Radiographics 2001) states that only venous (60 second) and late images
(3-5 mm) are necessary. What is your opinion?
| Answer:
Assuming that the patient is not hypotensive, a good protocol would
be arterial phase at 25 seconds, late corticomedullary phase at
50-60 seconds and a 3-4 minute delayed phase. If you use thin sections,
you can do excellent CT angiography of the renal artery and make
the diagnosis of renal artery injury. If the patient is in shock/hypotensive
then the delay may need to be longer. |
3.
What is your protocol for evaluating the chest, abdomen and pelvis in
trauma patients- do you perform a noncontrast CT for the upper abdomen
before performing the contrast CT?
| Answer:
We go straight to contrast enhanced CT and do not do non-contrast
studies. I have never been convinced the added time and radiation
provides any useful information that the contrast scans will not
provide. Let me know if you feel otherwise? |
4.
Blunt abdominal trauma and vascular lesions of the spleen are strongly
associated. Traumatic intrasplenic pseudoaneurysms are acknowledged
mechanism of delayed splenic rupture. In our experience, such lesions
can be difficult to detect with standard predelay (ca. 60 sec). Would
you recommend to scan earlier, say after 35 seconds, in addition, if
extravasation or splenic injury is suspected?
| Answer:
If splenic artery aneurysm or bleed is suspected I would use arterial
phase imaging at 25 seconds for optimal detection. |
References
Roos JE, Hilfiker P, Platz A et al. MDCT in emergency radiology: Is
a standardized chest or abdominal protocol sufficient for evaluation
of thoracic or lumbar spine trauma? AJR 2004; 182: 959-968.
- Summary:
In this series of 82 trauma patients, 4 slice MDCT was performed with
2.5 mm collimation. In patients with spine fractures, an additional
acquisition was performed to evaluate the spine, using 4 x 1 mm collimation.
From the original datasets using 2.5 mm collimation, targeted spine
reconstructions were performed with 3 mm slice thickness, 1.5 mm reconstruction
interval, and compared to the higher resolution 1 mm datasets which
served as the standard for spinal fracture classification. These studies
were added to 50 scans of patients without fractures and reviewed
by 2 observers. Using the 2.5 mm collimation datasets, the reviewers
demonstrated 97-98% sensitivity and 97% specificity for major spinal
fractures, and all minor fractures were detected by both observers.
A higher percentage of the 1 mm collimation datasets were graded as
excellent (80%) compared to the 2.5 mm datasets (68%). Furthermore,
the multiplanar reformations from the 1 mm datasets were superior,
due to statistically increased image degradation in the 2.5 mm datasets.
The authors conclude that the targeted reconstructions from the 2.5
mm datasets are accurate for detection and classification of spine
fractures.
Wintermark
M, Mouhsine E, Theumann N, Mordasini P, van Melle G, Leyvraz PF and
Schnyder P. Thoracolumbar spine fractures in patients who have sustained
severe trauma: Depiction with MDCT Radiology 2004; 227: 681-689.
- Summary:
In this study comparing conventional radiography to MDCT of the thoracolumbar
spine, retrospective review of the images was performed in 100 consecutive
patients, 26 of whom manifested 66 vertebral fractures. Conventional
radiography was 33% sensitive, and MDCT 97% sensitive. The 4 slice
MDCT technique included thoracic caudocranial CT with 4 x 2.5 mm collimation,
and abdominal-pelvic craniocaudal CT with 4 x 2.5 mm collimation.
From these datasets, the spine was reconstructed with 2.5 mm thick
sections and 2 mm interval, supplemented by sagittal and coronal reformations
of the thoraco-lumbar spine.
Alkadhi
H, Wildermuth S, Desbiolles L et al. Vascular emergencies of the thorax
after blunt and iatrogenic trauma: Multidetector row CT and 3D imaging.
Radiographics 2004; 24: 1239-1255.
- Summary:
A 4 slice MDCT scanner was used in this study, and 150 mL of 320 mgI/ml
isosomolar contrast infused at 3 mL/second and a bolus tracking timing
protocol . The data acquisition protocol is reported as 4 x 1 collimation
for arterial phase imaging, using 6 mm feed per rotation, 1 mm reconstruction
thickness and a .6 mm reconstruction increment. For venous phase,
acquisition was initiated 65-75 seconds after injection, using 4 x
2.5 mm collimation, 15 mm feed per rotation, 3 mm reconstruction thickness
and a 2 mm reconstruction interval. This article provides CME credit.
Harris
AC, Zwirewich CV, Lyburn ID, Torreggiani WC and Marchinkow LO
CT findings in blunt renal trauma Radiographics 2001; 21: S201-214.
- Summary:
This review article begins with an overview of the classification
of renal injuries, followed by a discussion of CT imaging protocol
and descriptions of CT findings in specific types of renal trauma.
The authors provide the following recommendations: Using 320 mgI/ml
contrast medium, 120 to 150 mL is infused at 2-4 mL/second. Scan delays
of 60-70 seconds for corticomedullary phase imaging and 3 - 5 minutes
for excretory-phase imaging are suggested.
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