99mTc-MIBI scintigraphy in musculoskeletal tumors.

UNLABELLED: The aim of this study was to assess the value of 99mTc-hexakis2-methoxyisobutylisonitrile (MIBI) scintigraphy in patients with clinical and radiologic features of primary or metastatic musculoskeletal tumors. METHODS: The scintigraphic findings for 84 patients were compared with the surgical and histologic findings. Each patient underwent three-phase bone scanning with 99mTc-methylene diphosphonate (MDP) and dynamic and static MIBI scintigraphy. The MIBI scans were evaluated by visual and quantitative analysis. The count ratio of the lesion to the adjacent or contralateral normal area (L/N) was calculated from the region of interest drawn on the MIBI scan. The Mann-Whitney test was used to determine the differences between the uptake ratios of malignant and benign lesions. RESULTS: Although increased MDP uptake was not specific for bone malignancy, a significant difference was found between benign tumors (L/N = 1.22 +/- 0.43) and malignant tumors (L/N = 2.25 +/- 1.03) on MIBI scans. Sensitivity and specificity were 81% and 87%, respectively. Forty-six of 53 proven benign lesions did not show significant MIBI uptake. The negative predictive value was 88%. In all seven sites of pathologic fracture, significant uptake was seen. However, three malignant lesions were not detected by MIBI scintigraphy, whereas seven benign lesions showed false-positive results. CONCLUSION: The major diagnostic worth of MIBI scintigraphy is its high negative predictive value. Although not capable of replacing tissue biopsy as a definitive diagnostic modality for musculoskeletal neoplasms, MIBI scintigraphy does appear to have a role in better preoperative assessment and in distinguishing between pathologic and simple fractures.

99Tcm-MIBI scintimammography for the detection of breast malignancies: the contribution of the count ratio to specificity.

We evaluated the efficacy of 99Tcm-sestamibi (MIBI) scintimammography for the detection of breast cancer in 332 patients. Two hundred and seven scans were confirmed by histological or cytological results; the other patients were examined because they belonged to high-risk groups or had dense fibroglandular breasts. Of 207 patients with histological confirmation, 112 positive studies were obtained: 86 true-positive and 26 false-positive. Scintimammography was negative in 95 patients: 88 true-negative and seven false-negative. Six of seven false-negative results were obtained in patients with impalpable tumours. The sensitivity, specificity, positive and negative predictive values were 92.5%, 77.2%, 76.8% and 92.6% respectively. The overall accuracy was 84.1%. To identify false-positive results, the count ratio of the target lesion to the contralateral normal area on 38 true-positive scans and in 26 false-positive examinations was calculated from the region of interest drawn on the 99Tcm-MIBI scan (L/N ratio). A significantly higher ratio was found for the true-positive scans (1.583 +/- 0.501 vs 1.246 +/- 0.213; P = 0.0002). In conclusion, 99Tcm-MIBI scintimammography is a sensitive and accurate method for the detection of breast malignancies.

[Technetium 99-m sestamibi bone scan in musculo-skeletal neoplasms].

It is often difficult to assess accurately the nature of a skeletal lesion. Problems include differentiating a malignant from a benign bone tumor, as well as determining the cause of a pathologic fracture. Such fractures may occur through osteoporotic bone as well as through neoplasm-affected bone. Thus, development of an imaging modality capable of distinguishing between such lesions is of importance. During 1996, we ran a prospective study in which results of Tc-99m-methyl-diphosphate (MDP) bone scans were compared with those of sestamibi (MIBI) bone scans and with subsequent biopsy and clinical course. The results of the bone scans were assessed by 2 independent "blinded" observers, and the ratios of counts in lesions to those in normal tissue (L/N ratios) were calculated. In cases of malignant (7) and benign (8) tumors, intensity of uptake in MDP scans were not predictive of degree of aggressiveness. On the other hand, MIBI bone scans demonstrated significant difference in intensity of uptake between benign and malignant bone tumors (L/N ratios 2.05 vs 2.75). In 5 of 8 benign lesions the L/N ratio was 1. In the others, increased uptake was minimal. In 2 patients changes in uptake in MIBI bone scan following chemotherapy appeared to be related to the degree of tumor necrosis achieved. While the MIBI bone scan cannot replace tissue biopsy as a definitive diagnostic modality in bone neoplasms, it does appear to allow better preoperative assessment and prognosis.

Gastric Emptying Half-time Following Silastic Ring Vertical Gastroplasty: A Scintigraphic Study (Preliminary Results).

BACKGROUND: The mechanism for weight loss following gastroplasty surgery is unknown. A few studies have checked gastric emptying patterns following gastroplasty, but none have analyzed their pattern over time. METHODS: Gastric emptying half-time of Tc-99 phytate-labeled semi-solid meal was studied in 23 obese non-diabetic and one diabetic patient (BMI 34.6-55.7). Gastric emptying was measured by gamma scintigraphy before Silastic Ring Vertical Gastroplasty (SRVG) and 1, 3 and 6 months following surgery. RESULTS: Gastric emptying half-times were maximal in all areas of the stomach 1 month after operation, declined to base-line 3 months following the procedure, and showed statistically significant delay in the upper area of the stomach 6 months after the operation. No correlation was found between the delay in food passage following surgery and loss of weight. CONCLUSIONS: Prolongation of gastric emptying half-time following surgery may be a result of two separate mechanisms: asymptomatic or early inflammatory processes in the ring area and pouch distention as a result of partial denervation.

A controlled double-blind comparison of intramuscular lorazepam and hydroxyzine as surgical premedicants.

The safety and efficacy of lorazepam and hydroxyzine, administered intramuscularly for surgical premedication, were compared in a double-blind placebo-controlled study. Ninety patients were given either 0.05 mg/kg of lorazepam (maximum 4 mg), 1.5 mg/kg of hydroxyzine (maximum, 100 mg), or 1 ml of normal saline before surgery. By 60 min after injection, patients given lorazepam or hydroxyzine were significantly (P less than 0.05) more sedated than the placebo-treated patients. The sedative effect of lorazepam lasted longer than that of hydroxyzine. Baseline anxiety scores were low; thus differences in the anxiolytic effect of the test drugs were not detected. Lorazepam-treated patients were consistently less able to recall postinjection events than patients treated with hydroxyzine or placebo. The frequency of injection-site reactions was similar in the three treatment groups. Premedication with lorazepam was considered satisfactory by a higher percentage of patients (77%) than was that with hydroxyzine (62%) or placebo (34%); only lorazepam was considered significantly (P less than 0.005) superior to placebo. The advantages of a longer duration of sedative effect, a greater effect on recall, and higher patient acceptance favor the use of lorazepam over hydroxyzine for surgical premedication.