Byung Tae Kim

Cerebral perfusion changes in mesial temporal lobe epilepsy: SPM analysis of ictal and interictal SPECT

We examined cerebral perfusion changes in mesial temporal lobe epilepsy (mTLE) by the statistical parametric mapping of brain single photon emission computed tomography (SPECT) images of 38 mTLE patients and 19 normal controls. Ictal and interictal SPECTs were compared with control SPECTs by independent t test, and ictal and interictal SPECTs by paired t test. We evaluated the number of heterotopic neurons in temporal lobe white matter, white matter changes of the anterior temporal lobe (WCAT) and ictal hyperperfusion of the temporal stem (IHTS). Left mTLE showed interictal hypoperfusion in the ipsilateral hippocampus, bilateral thalami, and paracentral lobules. Right mTLE showed hypoperfusion in bilateral hippocampi, contralateral insula, bilateral thalami, and paracentral lobules. Both mTLEs showed ictal hyperperfusion in bilateral temporal lobes with ipsilateral predominance, and in the anterior frontal white matter bilaterally. By paired t test, ictal hyperperfusion was found in the ipsilateral temporal lobe, temporal stem, hippocampus, thalamus, putamen, insula, and bilateral precentral gyri, whereas ictal hypoperfusion was found in bilateral frontal poles and middle frontal gyri. Fifteen patients showed WCAT and 19 showed IHTS, a weak correlation was observed between WCAT and IHTS (r = 0.377, P = 0.02). WCAT was found to correlate with an early seizure onset age. In 35 patients, heterotopic neurons were found in the white matter of the resected temporal lobe, but the number of heterotopic neurons did not correlate with WCAT or IHTS. In summary, the cerebral perfusion patterns of mTLE suggest interictal hypofunction and ictal activation of the cortico-thalamo-hippocampal-insular network and ictal hypoperfusion of the anterior frontal cortex.

Relationship between Gastrointestinal F-18-fluorodeoxyglucose Accumulation and Gastrointestinal Symptoms in Whole-Body PET.

The pattern and intensity of F-18-FDG uptake in the gastrointestinal (GI) tract are variable and can often cause confusion. The purpose of this study was to evaluate the relationship between GI tract symptoms and GI uptake of F-18-FDG. We evaluated whole-body FDG-PET of 314 persons (M:F = 147:167; 13-83 years) in whom pathologic GI tract disorders had not been observed. Uptake score and pattern were evaluated visually. Symptoms were grouped as follows: diarrhea, constipation, and neither diarrhea nor constipation. Among symptom groups, there was no statistically significant difference in FDG uptake score. But intense FDG uptake with focal pattern, which can cause confusion, was observed more frequently in the descending colon of patients with constipation than in those with diarrhea or without GI symptoms. When focal intense FDG uptake is observed in the abdomino-pelvic area, stricter attention to GI symptoms would improve the specificity of whole-body FDG-PET.

Cerebral perfusion abnormality in narcolepsy with cataplexy

To investigate abnormal cerebral perfusion in narcoleptics with cataplexy, 25 narcoleptics with cataplexy and 25 normal controls were enrolled in this study. Cerebral perfusion was measured by brain single photon emission computed tomography (SPECT) using 99mTc-ethylcysteinate dimer. Patients and normal controls had not received any medication prior to the SPECT scan. Differences in cerebral perfusion between narcoleptics and normal controls were subjected to statistical parametric mapping (SPM) analysis. Overnight polysomnography and multiple sleep latency test (MSLT) were performed in all patients. Brain SPECT was carried out on all patients and normal controls during the waking state. Clinical symptoms and MSLT results of all patients are in accord with the International Classification of Sleep Disorders criteria for narcolepsy. MSLT showed a short mean sleep latency (1.69 +/- 1.0 min) and 2-5 sleep onset REM periods in individual patient. SPM analysis of brain SPECT showed hypoperfusion of the bilateral anterior hypothalami, caudate nuclei, and pulvinar nuclei of thalami, parts of the dorsolateral/ventromedial prefrontal cortices, parahippocampal gyri, and cingulate gyri in narcoleptics [P < 0.05 by Students t test with false discovery rate (FDR) correction]. Significant hypoperfusion in the white matter of frontal and parietal lobes was also noted in narcoleptics. This study shows reduced cerebral perfusion in subcortical structures and cortical areas in narcoleptics. The distribution of abnormal cerebral perfusion is concordant with the pathway of the cerebral hypocretin system and may explain the characteristic features of narcolepsy, i.e., cataplexy, emotional lability, and attention deficit.

Glucose hypometabolism of hypothalamus and thalamus in narcolepsy

It has been hypothesized that hypothalamus is involved in narcolepsy. The relative difference between cerebral glucose metabolism of 24 narcoleptic patients and 24 normal controls was studied using 18F‐fluorodeoxy glucose positron emission tomography. Patients with narcolepsy showed significantly reduced cerebral glucose metabolism in bilateral rectal and subcallosal gyri, the medial convexity of right superior frontal gyrus, bilateral precuneus, right inferior parietal lobule, and in left supramarginal gyrus (uncorrected p < 0.001). Bilateral posterior hypothalami and mediodorsal thalamic nuclei showed hypometabolism with significance at the level of corrected p < 0.05, with small volume correction. This study showed cerebral glucose hypometabolism of the hypothalamus‐thalamus‐orbitofrontal pathways in the narcoleptic brain. Ann Neurol 2004

Diffuse Thyroid Uptake Incidentally Found on 18F-Fluorodeoxyglucose Positron Emission Tomography in Subjects without Cancer History

Objective We investigated the clinical significance of incidental diffuse thyroid uptake (DTU) on 18F-FDG PET in subjects without a history of cancer. Materials and Methods This study included 2062 studies from adults who underwent 18F-FDG PET as a cancer screening program. Subjects were divided into the following two groups: with (group I) or without (group II) DTU. The presence of DTU and the thyroid visual grading score were compared with thyroid function tests, serum anti-microsomal antibody (AMA) levels, and the presence of diffuse parenchymal change (DPC) on ultrasonography (USG). Results DTU was found in 6.6% of the scans (137/2062). Serum thyroid stimulating hormone (TSH) and AMA levels were significantly higher in group I than in group II. Increased AMA level (55.1%) and DPC (48.7%) were more frequently found in group I (p < 0.001). The proportion of subjects with any abnormal results in serum free thyroxine, triiodothyronine, TSH, or AMA levels or DPC on USG was significantly higher in group I than in group II (71.5% vs. 10.6%, p < 0.001), and was significantly and gradually increased according to the visual grading score group (0 vs. 1-2 vs. 3-4 = 10.6% vs. 58.5% vs. 90.9%, p < 0.001). TSH and is AMA levels were significantly increased according to the visual grading score. Conclusion The presence or degree of incidental DTU on 18F-FDG PET is closely correlated with increased serum AMA and TSH levels, and the presence of DPC on USG. Therefore, the most plausible pathological cause of DTU may be cell damage by an autoimmune mechanism.

Comparison between 18 F-FDG PET/CT and EMG Mapping for Identifying Dystonic Superficial Muscles in Primary Cervical Dystonia: Preliminary Results

PurposeThis study was conducted to compare 18F-FDG PET/CT and electromyography (EMG) mapping in patients with primary cervical dystonia (PCD) to find dystonic superficial cervical muscles.MethodsTen consecutive patients with PCD (M:Fu2009=u20095:5, age 44u2009±u200913xa0years) whose dystonic posture was not relieved with conventional muscle relaxant therapy were included. Target cervical muscles for the comparison between 18F-FDG PET/CT and EMG mapping were four representative superficial bilateral cervical muscles: splenius capitis muscle, sternocleidomstoid muscle, upper trapezius muscle, and leavator scapulae muscle. The diagnostic efficacy was compared between 18F-FDG PET/CT and EMG mapping using physical exam and measurement of rotation angle as the gold standard.ResultsAmong 80 muscles evaluated, there were 21 (26%) dystonic superficial cervical muscles assessed with physical exam and motion analysis. The sensitivity, specificity, and accuracy for localizing dystonic muscles were 76, 92, and 88% for 18F-FDG PET/CT, and 95, 66, and 74% for EMG mapping, respectively. The sensitivity of EMG mapping was significantly higher than that of 18F-FDG PET/CT. In contrast, 18F-FDG PET/CT was significantly superior to EMG mapping for specificity and accuracy.Conclusions18F-FDG PET/CT is more specific and accurate than EMG mapping for finding superficial dystonic cervical muscles. The high sensitivity of EMG mapping suggests that 18F-FDG PET/CT and EMG mapping are complementary for finding dystonic superficial cervical muscles.