Preoperative computed tomography scans for parotid tumor evaluation.

OBJECTIVE: We sought to determine whether an advantage is obtained in the routine use of computed tomography (CT) scans in preoperative assessments of parotid tumors. METHODS: A prospective study of 32 consecutive cases of patients who underwent evaluation for parotidectomies was performed. Twenty-nine received preoperative CT scans. The scans were systematically reviewed to see if they correlated with the clinical findings. Specifically, we compared clinical and CT assessments of tumor size, location, density, and malignancy. Further comparisons were performed based on postoperative tissue pathology. RESULTS: In our series of patients, routine preoperative CT scans resulted in the discovery of details not revealed on clinical examination: some masses were found to be extra-parotid rather than primary parotid tumors, some tumors deemed to be deep were superficial, tumor density was more clearly identified, and certain pathology correlates were clarified. Most importantly, there were instances of detection of additional tumors in the same lobe, and in one instance in the opposite lobe, that were not otherwise noticed. CONCLUSIONS: To reduce errors of omission in the treatment of suspected parotid tumors, it would seem appropriate to consider the inclusion of CT scans for the routine preoperative evaluation of all parotid masses.

Trigeminal neuralgia (tic douloureux): MR imaging assessment.

The magnetic resonance (MR) imaging studies and clinical records of 29 patients with typical or atypical trigeminal neuralgia (TN) were retrospectively reviewed and compared with the MR studies of 30 patients imaged for reasons unrelated to the fifth cranial nerve. The symptomatic patients were in three groups. Group 1 included those without masses or multiple sclerosis (MS) and those who had not undergone microvascular decompression; group 2, those who underwent microvascular decompression; and group 3, those with masses or MS. Twenty-seven percent of the control group and 57% of the symptomatic patients without masses or MS showed vessel contact with the root entry zone of the preganglionic segment of the fifth cranial nerve. Vessel contact in the symptomatic groups was generally indistinguishable from that seen in the normal group. Fifteen percent of the patients had MS or masses. It is concluded that MR imaging is useful in evaluating patients with TN by facilitating identification of MS or masses but is not helpful in selecting patients with vascular contact who might benefit from microvascular decompression.

The radiologic assessment of trigeminal neuropathy.

The clinical and radiologic records of 76 patients with trigeminal neuropathy and an abnormal imaging study (CT and/or MR) were analyzed retrospectively. The trigeminal nerve (cranial nerve V) was divided into proximal (brainstem, preganglionic, gasserian ganglion, and cavernous sinus) and distal (extracranial V1, V2, and V3) segments. Lesions were organized according to segments and correlated with the type and distribution of clinical symptoms or signs. The purpose of the study was to (1) determine the efficacy of clinical localization of cranial nerve V lesions, (2) compare CT and MR for cranial nerve V imaging, (3) develop an MR protocol for effective cranial nerve V imaging, and (4) construct a differential diagnosis by anatomic segment for lesions of cranial nerve V. Clinical localization was found to be extremely inaccurate. CT was not as sensitive as MR for lesions involving the basal cisterns and skull base and will not detect the most common brainstem lesions (small infarcts and multiple sclerosis plaques). The MR protocol developed does not rely heavily on clinical localization. On the basis of lesions found in this series, a differential diagnosis by segment was developed. Patients with cranial nerve V symptoms should undergo MR imaging according to the protocol provided in this article. CT is not as effective as MR in imaging some cranial nerve V segments. Clinical localization is inaccurate.

The radiologic assessment of trigeminal neuropathy.

The clinical and radiologic records of 76 patients with trigeminal neuropathy and an abnormal imaging study (CT and/or MR) were analyzed retrospectively. The trigeminal nerve (cranial nerve V) was divided into proximal (brainstem, preganglionic, gasserian ganglion, and cavernous sinus) and distal (extracranial V1, V2, and V3) segments. Lesions were organized according to segments and correlated with the type and distribution of clinical symptoms or signs. The purpose of the study was to (1) determine the efficacy of clinical localization of cranial nerve V lesions, (2) compare CT and MR for cranial nerve V imaging, (3) develop an MR protocol for effective cranial nerve V imaging, and (4) construct a differential diagnosis by anatomic segment for lesions of cranial nerve V. Clinical localization was found to be extremely inaccurate. CT was not as sensitive as MR for lesions involving the basal cisterns and skull base and will not detect the most common brainstem lesions (small infarcts and multiple sclerosis plaques). The MR protocol developed does not rely heavily on clinical localization. On the basis of lesions found in this series, a differential diagnosis by segment was developed. Patients with cranial nerve V symptoms should undergo MR imaging according to the protocol provided in this article. CT is not as effective as MR in imaging some cranial nerve V segments. Clinical localization is inaccurate.

Synthesis of [18F]2-deoxy-2-fluoro-D-glucose from highly reactive [18F]tetraethylammonium fluoride prepared by hydrolysis of [18F]fluorotrimethylsilane.

18F-Labeled fluorotrimethylsilane was prepared by nucleophilic substitution of chlorotrimethylsilane with reactor produced [18F]fluoride. Hydrolysis of fluorotrimethylsilane by aqueous tetraethylammonium hydroxide followed by removal of water with a mechanical pump gave a powerful source of no carrier added nucleophilic 18F. Reaction of this purified 18F preparation with 4,6-benzylidene-1-beta-O-methyl D-mannopyranoside-2.3-cyclic sulfate was complete in 2 min at 80 degrees C and gave two labeled products with similar retention times on reverse phase HPLC. Allowing for decay and handling losses during deprotection, the maximum yield of [18F]2-deoxy-2-fluoro-D-glucose from no-carrier added tetraethylammonium fluoride was 50%. Incorporation of 18F into organic products was 30% complete in 10 min at room temperature. An identical time-course was observed for reaction of 3-O-triflyl-1,2-5,6-diisopropylidene-D-allofuranose, the starting material for 3-deoxy-3-fluoro-D-glucose. Reaction of tetraethylammonium fluoride with chlorotrimethylsilane was more rapid and much more tolerant of water than the fluorosugar reactions. Chlorotrimethylsilane can be used to recover unreacted 18F from reaction mixtures.

Binding of psychotropic drugs to isolated alpha-acid glycoprotein.

Alpha1-acid glycoprotein (alpha1-AG) was purified from human sera, and its binding properties with respect to psychotropic drugs were examined by equilibrium dialysis methods in order to clarify the specificity of binding. Radioactive imipramine, a tricyclic antidepressant, was used as the primary ligand. Other drugs, representative of different classes, were tested as potential inhibitors of the alpha1-AG-imipramine binding. The K(a) for imipramine was 2.8 x 10(5) (+/- 0.8) M(-10 (mean +/- S.D.). Chlorpromazine, fluphenazine, thioridazine, loxapine and thiothixene, which are antipsychotic drugs, were competitive inhibitors of imipramine binding, and their K(a) values were in the same range. Propranolol, haloperidol and diazepam were also competitive inhibitors but their affinities were lower. Molindone, an indolic antipsychotic, when tested at the same concentrations as the other drugs, did not affect imipramine binding. Trihexyphenidyl, an anti-Parkinson drug, was a potent but noncompetitive inhibitor. These data identify the antidepressant and major tranquilizer drugs that exhibit high affinity for alpha1-AG and indicate that alpha1-AG may account for 40 per cent of total imipramine bound in serum. Since in psychiatric clinical practice two drugs are frequently administered together, possible competitive effects are discussed as well as the potential role of alpha1-AG in psychiatric illness.