Risk of radiation injury from performing a CT scan of the chest in a patient with ataxia-telangiectasia

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Risk of radiation injury from performing a CT scan of the chest in a patient with ataxia-telangiectasia

5/8/2013
I have a 6 year-old Caucasian female with Ataxia-Telangiectasia (A-T). She was referred to me for evaluation and management of Immunodeficiency. She has a few documented respiratory infections. However she has had chronic cough for the last 3 years. Her lab data showed:
IgG 578( Low Normal for her age) IgA 82( Normal) IgM 195( High for her age)
IgE( Low)
Normal protein antibody titers
Non protective pneumococcal titers( <1.3)on 16/23 serotypes( Pre vaccine)
Very low B and T cell subsets
Low lymphocyte proliferative response with PHA and antigens

Two questions
1) Mother is refusing post vaccine titers. Should I go ahead and start IVIG without checking post vaccine titers
2) History of chronic cough with a few documented respiratory infections. I think she has more than what mother is describing. My concern is that she is having Bronchiectasis and needs aggressive evaluation and management. Mother is refusing any imaging study due to concern of radiation in A-T. I want to get a CT scan. Question is that How much is a risk for getting such study due to A-T. Thanks.

Thank you for your inquiry.

I am going to forward your inquiry to Dr. Gertjan Driessen, an internationally recognized expert in ataxia-telangiectasia. When we receive a response from Dr. Driessen, we will forward it to you.

Thank you again for your inquiry.

Sincerely,
Phil Lieberman, M.D.

We received a response from Dr. Gertjan Driessen. Thank you again for your inquiry and we hope this response is helpful to you.

Sincerely,
Phil Lieberman, M.D.

Response from Dr. Gertjan Driessen:
It is indeed very important to know whether this patient has bronchiectasis as a result from her (mild?) antibody deficiency. Unfortunately mother refuses to measure post vaccination titers, although it is likely that polysaccharide responses are impaired. The most pragmatic approach is to start immunoglobulin replacement, since the chronic cough suggest a form of chronic lung disease. CT scans are relatively contraindicated because of the radiosensitivity. Are you able to perform chest MRI instead? If not, a simple CXR might be able to pick up more extensive bronchiectasis and involves much less irradiation. If mother continues to refuse any imaging, it might be better to start a trial of immunoglobulin replacement despite the lack of evidence for chronic lung disease. If her clinical condition substantially improved during at least 6 month of replacement, you are probably on the right track.

Gertjan Driessen

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