Evaluation of radioiodine therapy in differentiated thyroid cancer subjects with elevated serum thyroglobulin and negative whole body scan using 131I with emphasize on the thallium scintigraphy in these subgroups.

OBJECTIVE: Negative diagnostic 131I whole body scans with elevated serum thyroglobulin (Tg) levels are found in 20% of patients with differentiated thyroid cancer (DTC). Empirical radioiodine treatment has been advocated by some researchers, but has had with controversial outcomes. This anterospective study was performed to examine this dilemma and also to determine the capability of thallium (201TI) scintigraphy in these patients. MATERIALS AND METHODS: A total of 21 patients who had a history of DTC and elevated serum Tg levels, together with a negative diagnostic 131I whole body scans (WBS), were included in the study. All patients underwent posttreatment 131I WBS. Patients with negative posttreatment 131I WBS then underwent 201TI scintigraphy. RESULTS: The 21 included patients (9 women and 12 men) had a mean age of 53 +/- 14.17 years. The mean pretreatment and posttreatment Tg levels were 227.23 +/- 208.50 ng/ml and 163.43 +/- 282.57 ng/ml, respectively (p value <0.05). Eleven cases showed at least a 50% decrease in Tg value (remission group), 6 patients revealed less than a 50% decrease in Tg value (stable group), while 4 subjects demonstrated an increment in posttreatment Tg relative to pretreatment Tg value (progression group). The cumulative and last 131I doses in the remission, stable, and progression groups were not significantly different (p value >0.05). In the posttreatment 131I WBS, 10 patients showed abnormal findings in their images. In a follow-up scan after 201TI treatment, 7 out of 11 patients had positive scans. CONCLUSION: The study indicates a positive effect of RAI therapy in DTC patients with elevated Tg and negative 131I WBS. In addition, 201TI scintigraphy can be useful as an alternative modality to improve tumoral detection in this situation and when access to a PET system is limited.

Initial and delayed stress phase imaging in a single-injection double-acquisition SPECT. The potential value of early 99mTc-MIBI redistribution in assessment of myocardial perfusion reversibility in patients with coronary artery disease.

UNLABELLED: Some studies reported that 99mTc-MIBI may redistribute in ischaemic myocardium and this phenomenon may have potential role for better assessment of viability by delayed 99mTc-MIBI imaging. Some studies also suggested that infusion of low dose dobutamine during delayed imaging may enhance the value of 99mTc-MIBI imaging for evaluation of viability. The aim of this study is to determine whether the observed changes of perfusion defects on delayed images are caused by early radiotracer redistribution or as a result of reversal partial volume effect secondary to inotropic stimulation. PATIENTS, METHODS: 89 patients with angiographically proven coronary artery disease (CAD) were enrolled in this randomized clinical trial study. In all cases, gated-SPECT images were obtained 60 minutes after stress with dipyridamole injection. Subsequently the patients were randomly allocated in two groups and the second imaging was performed at 120th minute during low dose dobutamine (dobutamine group; 45 cases) or placebo infusion (placebo group; 44 cases). Difference between summed stress score of the first (SSS1) and second (SSS2) stress images (DeltaSSS) was considered as a marker of reversibility in single-injection double-acquisition (SIDA) protocol. Also summed difference score (SDS) was recorded as a marker of reversibility in standard stress/rest, double-injection double-acquisition (DIDA) protocol. DeltaSSS of the two studied groups were compared. Also the correlation and agreement between DeltaSSS and SDS were analyzed. RESULTS: A significant difference was found between SSS1 (median 15, range 0-48) and SSS2 (median 11, range 0-42) in total patients (p < 0.0001). A significant correlation was noted between DeltaSSS and SDS in dobutamine group (r = 0.58, p = 0.002) as well as in placebo group (r = 0.57, p < 0.0001). Considering DIDA protocol as a standard reference method, the influence of dobutamine infusion was not shown to be significantly different from the placebo effect on the magnitude of fixed or reversible perfusion defects in SIDA protocol. CONCLUSION: The changes in the magnitude of the perfusion defects may occur in the first hours of 99mTc-MIBI injection in the stress phase imaging. These changes correlate well and are in agreement with perfusion improvement on the rest images. This phenomenon may be independent of improvement in myocardial function, in more delayed imaging or following inotropic augmentation, and thus is likely due to 99mTc-MIBI redistribution. This may open new technical and clinical aspects and potentials for 99mTc-MIBI imaging.

Characteristic features of pneumothorax on lung perfusion scan

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Fecal impaction detection on a bone scan

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Computer-aided manufacturing of implants for the repair of large cranial defects: an improvement of the stereolithography technique.

The objective of this study is to demonstrate the utility of geometric modeling in cranioplasty; in other words, to use geometric modeling to generate a prototype that will be used as the base structure of a composite prosthesis for covering cranial defects. This geometric model is easy to manipulate and can be modified. To achieve this goal, the top surface of a cranial bone flap is digitized using a portable coordinate measurement machine. Intentionally, a sub-surface of the bone flap, representing the skull defect, was not digitized. A geometric model of the bone flap is generated that includes the undigitized region. With the technique described in this paper the authors generated the geometric model of the undigitized region (the skull defect). The geometric model of the bone flap is further manipulated and a series of conical cavities are introduced. Prototypes of the geometric models are manufactured using stereolithography. The clinical implications of this technique are discussed.

Stereolithography: application to neurosurgery

Computer-aided design (CAD) and computer-aided manufacturing (CAM) by stereolithography are already being widely used in industry for the design and manufacture of new parts and have already shown accuracy in reproducing the desired model. The only shortcoming of this technique is that it can only make one model at a time, a "prototype." It cannot be used for mass production. It is precisely this property, namely making a prototype, that makes it so attractive in reconstructive surgery and implantation of prostheses, where each "part" has to be adapted to the unique anatomy of the patient. It was not until the early nineties that reports of the application of stereolithography to reconstructive surgery appeared in the literature, and even now they are scarce. However, it is a very promising technique, and we think that it is important for physicians to familiarize themselves with this concept.