The "Hot Nose" Sign in the Cerebral Radionuclide Angiogram Robert D. Tien, Dorothy S. Lin, and NicholaS.Kutka

intracranial pressure of any cause 6 or (B) anatomic occlusion of one or both internal carotid arteries. Hepatocellular dysfunction in hepatic encephalopathy causes intrahepatic and extrahepatic shunting of portal venous blood into the systemic circulation, and various toxic substances, such as ammonia, accumulate in the brain and interfere with its metabolism. 7 Beside the functional cerebral changes, structural changes such as hyperplasia of protoplasmic-type astrocytes occur principally in the cortex, but they also occur in other parts of the brain. There is cerebral edema in some individuals.8 Hence, hepatic encephalopathy certainly is one of the causes of increased intracranial pressure.

64-YEAR-OLD MAN came to the emergency room with altered mental status. He A had a history of adenocarcinoma of the small bowel for which he had undergone surgical resection. Brain imaging was done to rule out metastases. On the anterior cerebral angiogram, increased tracer uptake in the early arterial phase was seen in the midline overlying the nasal area, which gradually diminished in the venous phase (Fig 1A) but was still quite prominent in the blood pool phase (Fig 1B). This phenomanon has been described as the " h o t nose ''1-3 sign. The static brain images did not show any evidence of brain metastases. The patient had an elevated serum ammonia of 280 ~g/dL (normal = 18 to 48 ~g/dL). Liver biopsy showed hepatic cirrhosis. The patient subsequently died of hepatic encephalopathy. The various causes for the "hot nose" sign are: 1. Ceased or decreased cerebral blood flow resulting in increased flow to the external carotid circulation. 1-5 These conditions include (A) functional occlusion such as cerebral death, cerebral atrophy, increased

From the Nuclear Medicine Service, Veterans Administration Medical Center, Houston, TX. Address reprint requests to Dorothy S. Lin, MD, Veterans Administration Medical Center, Nuclear Medicine Service (115), 2002 Holcombe Blvd, Houston, TX 77030. This is a US government work. There are no restrictions on its use. 0001-2998/92/2204-0010500.00/0

Fig 1. (A) Sequential images at 2-second intervals of a technetium-99m pertechnetate anterior cerebral angiogram show early arterial accumulation of tracer in the midline overlying the nasal area, which somewhat diminished in the venous phase. The cerebral perfusion is symmetrically slightly decreased. (B) Blood pool image obtained after images in (A) shows relative prominence of tracer uptake overlying the nasal area. Seminars in Nuclear Medicine, Vol XXII, No 4 (October), 1992: pp 295-296

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2. U s e o f p s y c h o t r o p i c a g e n t s I c a u s i n g (1) n a s a l c o n g e s t i o n a n d stuffiness d u e to p h e n o t h i a z i n e s , c h l o r p r o m a z i n e , a n d thioridazine; (2) g e n e r a l i z e d v a s o d i l a t i o n d u e to p h e n o t h i a z i n e a n d d o p a m i n e r g i c agents; a n d (3) relatively i n c r e a s e d flow t h r o u g h t h e e x t e r n a l c a r o t i d system. 3. I n c r e a s e d e x t e r n a l c e r e b r a l flow such as s e e n in c a s e s o f h y p e r t h y r o i d i s m . 1 4. N a s a l i n f l a m m a t i o n a n d h y p e r v a s c u l a r i ty 1,6 such as s e e n in c a s e s o f a c u t e sinusitis, possible nasopharyngeal vascular tumors, and arteriovenous malformation. COMMON 1. Increased intracraniai pressure: cerebral vascular accident, 1 transient ischemic attack, t subdu-

ral hematoma, l herpes encephalitis, 2 hepatic encephalopathy* 2. Occlusion of one or both internal carotid arteries3 3. Psychotropic agents / 4. Brain death 4,5 UNCOMMON

1. Sinusitis6 RARE

1. Cerebral atrophy I 2. Hyperthyroidism 1

*The present case.

REFERENCES

1. Joe SH, Watts G, Mena I: The significance of increased nasopharyngeal flow in cerebral radionuclide angiogram: "Hot nose" phenomenon. Clin Nucl Med 2:221-226, 1977 2. Mishkin FS: Radionuclide angiogram and scan findings in a case of herpes simplex encephalitis. J Nuci Med 11:608-609, 1970 3. Watts G, Mena I, Joe sn: Cerebral radioisotope angiogram: The significance of increased external carotid circulation. J Nucl Med 17:527, 1976 (abstr) 4. Mishkin F: Determination of cerebral death by radionuclide angiography. Radiology 115:135-137, 1975

5. Goodman JM, Mishkin FS, Dyken M: Determination of brain death by isotope angiography. JAMA 209:18091872, 1969 6. Datz FL: Gamuts in Nuclear Medicine (ed 2). Norwalk, CT, Appleton & Lange, 1987, p 45 7. Wilson JD, Braunwald E, Isselbacher KJ, et al (eds): Harrison's Principle of Internal Medicine (ed 12). New York, NY, McGraw-Hill, 1991, pp 1348-1349 8. Robbins SL, Kumar V: Basic Pathology (ed 4). Philadelphia, PA, Saunders, 1987, p 568

The "hot nose" sign in the cerebral radionuclide angiogram.

The "Hot Nose" Sign in the Cerebral Radionuclide Angiogram Robert D. Tien, Dorothy S. Lin, and NicholaS.Kutka intracranial pressure of any cause 6 or...
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