Increased flurodeoxyglucose uptake observed in the diaphragm and vocal cords on whole body 18F flurodeoxyglucose positron emission tomography with computerized tomography scan in a patient with uncontrolled hiccups of unknown origin

Sir,

The knowledge of physiological 18F flurodeoxyglucose (FDG) uptake patterns is essential for interpreting physician to prevent false-positive reporting. Here we present a case of uniform FDG uptake noted in the diaphragm in a 51-year-old man with uncontrolled hiccups of unknown origin for past 10 years. The patient underwent 18F FDG positron emission tomography with computerized tomography (PET/CT) for suspected paraneoplastic syndrome. No FDG avid malignancy was noted, however, increased FDG uptake was noted in the diaphragm, including the crura and in the vocal cords probably from uncontrolled hiccups. The whole body maximum intensity projection images (a) demonstrated increased uptake in the vocal cords (thin arrow), in the diaphragm (hollow arrow) and in the crura (solid arrow). Transaxial PET attenuation corrected image through the neck (b) demonstrate uptake in the vocal cords (thin arrow). Transaxial PET attenuation corrected image through the abdomen (c) demonstrate uptake in the diaphragm (hollow arrow). Coronal PET attenuation corrected image (d) demonstrated the uptake in the crura (solid arrow) [Figure 1].

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Figure 1 Images of the 18F flurodeoxyglucose positron emission tomography (PET)/computerized tomography scan of the 51-year-old male. (a) The whole body maximum intensity projection images demonstrating increased uptake in the vocal cords (thin arrow), in the diaphragm (hollow arrow) and in the crura (solid arrow), (b) Transaxial PET attenuation corrected image through the neck, demonstrating uptake in the vocal cords (thin arrow). (c) Transaxial PET attenuation corrected image through the abdomen, demonstrating uptake in the diaphragm (hollow arrow), (d) Coronal PET attenuation corrected image demonstrating the uptake in the crura (solid arrow)

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The role of 18F FDG PET/CT is already described in suspected paraneoplastic syndrome.[1] Increased FDG uptake is observed in the muscles from increased physical activity prior to injection of 18F FDG or during uptake phase that is what seemed to be demonstrated on this scan.[2] A hiccup is an involuntary, intermittent spasmodic contraction of the diaphragm and intercostal muscle that results in a sudden inspiration and ends abruptly with closure of the glottis.[3] The etiology of self-limited and intractable hiccups includes disorders affecting the peripheral and central nervous system, metabolic or drug-mediated factors, infectious, psychogenic and idiopathic causes. This patient has been having hiccups for 10 years and has undergone extensive work-up. No culprit disease entity has been found. Increased FDG uptake is noted in the muscles of mastication from chewing gum 3 h prior to FDG injection.[4] Incidental FDG uptake is observed in the diaphragm, the tongue and vocal cords in a crying child and in the diaphragm in the hyperventilating patient.[56] Increased FDG uptake is also noted in the laryngeal muscles in patients who were talking during the FDG-uptake phase and in patients with recurrent nerve palsy, causing increased uptake in the vocal cord on the contra lateral side.[7] In our patient we observed increased uptake in the diaphragm and in the vocal cords is from increased utilization of these muscles from persistent hiccups.