Ask The Radiologist
Q: I am 28 years old and 25 weeks pregnant. Is it safe for the baby if I get an MRI done?
A: There are no known dangers or side effects connected to an MRI scan since radiation is not used. There is a small theoretical risk to the fetus in the first 12 weeks of pregnancy, and therefore scans are not performed on pregnant women during this time. After the first trimester, generally the procedure is considered to be risk-free.
Q: Are titatanium clip markers seen on CT or MRI scans. Is it safe to undergo either examination.
A: Yes, titanium is considered to be a metal and will be visible on CT as a white material or spot. Artifacts can be seen on CT known as "streak" artifacts. Titanium is a non-magnetic material. It would appear without signal (signal-void) on MRI images. Overall, it is safe for a patient to undergo either CT or MRI with titanium material in their body.
Q: I had a nuclear bone scan study. There is a spot of uptake next to spine. I was told it was "my kidney getting rid of radioactive dye". Wouldn't the whole kidney light up and not just a spot?
A: Because very low dose of radioactive material is used, radioactive material has to reach a certain concentration to be visible as a spot. This usually happens when it is already being excreted out of the kidney concentrated in the urine. Therefore it generally will not be visible in the kidney but rather when the kidney is "getting rid of the dye".
Q: My cervical MRI report states "C5-C6 disc/osteophyte complex obliterating the anterior subarachnoid space with miminal narrowing of the left intervertebral foremen. C7-T1 disc/osteophyte encroaching on anterior subarachnoid space with possible encroachment on left C8 nerve root". Does this mean I have cord compression? Is this a hard or soft herniation? Does this mean I have some stenosis? Can it be determined from the MRI if there is definite nerve impingement?
A: There is no evidence of spinal cord compression from the above. The spinal cord lives in the spinal canal and is bathed by a fluid called CSF (cerebro-spinal fluid). Changes above imply canal stenosis without evidence of cord compression. Disk-osteophyte complex implies a "hard" disk displacement in which the displaced portion has undergone calcification or ossification. The term hard disc is most often used in reference to the cervical spine to distinguish chronic hypertrophic and reactive changes in the periphery of the disc from acute herniation of soft, predominantly nuclear tissue. There is no radiology examination (X-ray, ultrasound, CT, MRI, scintigraphy) that can with certainty detect the nerve impingement or entrapment. MRI can only suggest it. The diagnosis comes from physical examination and non-radiologic testing.
Q: If older scans were done on 1.5T MRI scanner can they still be compared successfully if a current scan is done on a 3.0T MRI scanner? Can there be difficulties in making comparisons?
A: For advanced clinical neuro assessment and therapeutics — especially for neurovascular diseases, neuro-oncology, and epilepsy — the technical and clinical experience suggest benefit of the 3.0 T MRI compared with the 1.5 T MRI. What this means, in layman's terms, reading radiologists can sometimes diagnose diseases earlier and find more lesions on 3.0T studies. It will however depend on the nature of abnormality. Some disease processes may show up equaly well on both scans. Others may show up better on 3.0T scans. So the correct answer: it depends. Sometimes there is no problem in making comparisons and other times there may be a limitation. If there is a limitation in making a comparison, the radiologist should make a statement regarding this in the report.
However, the most important point for the patients to keep in mind - experience and training of a radiologist is usually much more important than the quality of the scanner.
Q: I was diagnosed with a serious condition called neurosarcoidosis. MRI report states that the lesions appear hypointense on T2 weighed images. What does it mean.
A: Sarcoidosis can involve any part of the nervous system and may involve the parenchyma of the brain and spine, nerve roots, the leptomeninges, the dura mater, and the surrounding bony structures. In most cases, the appearance of lesions is nonspecific so that sarcoidosis is included in a broad differential diagnosis. To answer your specific question - in the setting of sarcoidosis, hypointense T2 signal may be related to calcification or fibrous tissue since this is considered to be a granulomatous disease with formation of calcified and noncalcified granulomas. In general low T2 signal (or signal void) may also be due to bone, air, fat and metal or other paramagnetic material.
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