As imaging technologies become increasingly advanced, it is possible to obtain detailed morphological information as well as functional imaging data. In some imaging technologies, the radiation dose increases with the ability to obtain better images or more detailed information. We encountered three cases of temporary bandage-shaped hair loss, which was caused by perfusion studies of the head by multi-detector row computed tomography (MDCT) for evaluation of cerebral blood flow in patients with vascular disorders. In all three patients with temporary hair loss, two angiographies of the head had been performed in the period of serial CT examinations. This suggested the possibility that radiation exposure from angiography performed in serial examinations, combined with the perfusion studies of the head with MDCT, played an important role in this temporary, bandage-shaped hair loss. Radiologists should be aware that a cumulative or multiplier effect of radiation exposure from multiple diagnostic techniques may result in hair loss and other types of radiation complications.

The decrease in CT values not only revealed a decrease of iodine concentration in the thyroid but also represented an increase of follicular cells and/or interstitial structures in the volume ratio secondary to it.

It is essential to diagnose thyroid dysfunction at an early stage because congenital hypothyroidism (CH) represents one of the most common preventable causes of delayed physical and psychological development, including mental retardation. US evaluates the shape of the thyroid gland. CT and scintigraphic examinations demonstrate iodine metabolism of the thyroid, but there is associated radiation exposure. We encountered two cases of congenital goiter, in which MRI was very helpful in confirming thyroid dysfunction and was very useful in making an accurate diagnosis.

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In this case, Tc-99m MDP bone scintigraphy was useful for diagnosing relapsing polychondritis, and Ga-67 citrate scintigraphy was helpful in determining the biopsy site.

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We report a case of intradiploic epidermoid cyst with focal internal enhancement. The patient was a 55-year-old woman presenting with right temporal head protrusion and head heaviness. Skull radiography and computed tomography demonstrated an expansile mass in the right diploic space. On magnetic resonance imaging, the mass showed makedly high signal T2-weighted images (T2WI) and intermediate to low signal on T1WI. On contrast-enhanced T1WI, there was nodular internal enhancement, which corresponded to neovascularity on pathology, as well as rim-like enhancement. It should be noted that internal enhancement, an indicator of malignant transformation, may be seen even in a benign epidermoid cyst.

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