A CT scan or MRI? This is a common consideration when doctors need more than a simple X-ray to look for Valley Fever in complex structures in the body. One study (Armbuster et al) described these and other imaging methods as “complementary” under the idea that more than one imaging test could find Valley Fever in ways the other tests could not.
Multiple tests can be involve time, expenses, side effects from contrast agents, and radiation (in CT). It is usually practical to pick the best one for the patient.
UCSF doctors Christopher Hess and Derk Percell wrote a quick article on the topic for brain imaging that could easily double as a Valley Fever imaging primer.
The advantages of computed tomography (CT):
- CT is much faster than MRI, making it the study of choice in cases of trauma and other acute neurological emergencies
- CT can be obtained at considerably less cost than MRI, and is sufficient to exclude many neurological disorders
- CT is less sensitive to patient motion during the examination. because the imaging can be performed much more rapidly
- CT may be easier to perform in claustrophobic or very heavy patients
- CT provides detailed evaluation of cortical bone
- CT allows accurate detection of calcification and metal foreign bodies
- CT can be performed at no risk to the patient with implantable medical devices, such as cardiac pacemakers, ferromagnetic vascular clips, and nerve stimulators
The advantages of magnetic resonance imaging (MRI):
- MRI does not use ionizing radiation, and is thus preferred over CT in children and patients requiring multiple imaging examinations
- MRI has a much greater range of available soft tissue contrast, depicts anatomy in greater detail, and is more sensitive and specific for abnormalities within the brain itself
- MRI scanning can be performed in any imaging plane without having to physically move the patient
- MRI contrast agents have a considerably smaller risk of causing potentially lethal allergic reaction
- MRI allows the evaluation of structures that may be obscured by artifacts from bone in CT images
There have been many disastrous side effects from contrast agents, but the above summary is very useful for Valley Fever imaging considerations. CT scans are often better for bone imaging while MRI testing tends to be better for soft tissue. PET Scans and the less expensive bone scintigraphy (aka Bone scans) are also options for accurate visualization of bone symptoms. When osteomyelitis attacks the bones in Valley Fever, these may also be a consideration.
The statements above are generalizations, however, and not necessarily absolute deal breakers for using a specific test for any person’s specific medical circumstances. It is important to enter a doctor’s office with knowledge about procedures and tests so you can be more comfortable understanding the doctor’s approach. This can help you ask your medical team the questions that could ensure your best possible medical care.
Source: Armbuster TG, Goergen TG, Resnick D, Catanzaro A. Utility of bone scanning in disseminated coccidioidomycosis: case report. J Nucl Med. 1977 May;18(5):450-4.