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Josef Machac

Publications and source records attributed to Josef Machac.

23 records · Page 2Linked to original sources
PubMed2002

Peptide and antibody imaging in lung cancer.

Noninvasive differentiation of malignant from benign pulmonary nodules and the staging of lung cancer are major challenges and opportunities for radionuclide imaging. Despite the performance of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging in addressing these needs, access to PET imaging in the United States and other countries is still limited for many people. Furthermore, FDG-PET imaging has left room for improvement. Thus, the need for addressing these diagnostic issues exists for a significant portion of the population of the United States and the rest of the world. Labeled antibody and peptide single-photon emission computed tomography imaging offers a reasonable alternative for these indications and comes close to FDG-PET imaging in performance, along with a lower cost when all overhead is included. Although these tracers have a high sensitivity in the diagnosis of primary and metastatic tumors, their specificity is limited by uptake in granulomatous disease, similar to that of FDG-PET. Regardless of these daunting challenges, radiolabeled antibody and peptide imaging deserves a recognized role in the clinical management of lung cancer.

Antibodies, Monoclonal↗
PubMed2002

Effect of high specific-activity sulfur colloid preparations on sentinel node count rates.

PURPOSE: Preliminary results by other investigators suggest that increasing the specific activity of Tc-99m nanocolloid preparations increases the measured counts in sentinel nodes compared with lower specific-activity (SA) preparations using the same initial injected dose. The authors set out to determine whether a similar result could be perceived with Tc-99m sulfur colloid (SC) preparations. METHODS: Twenty-three consecutive patients (low SA group) with successful visualization of sentinel nodes by lymphoscintigraphy before our standard protocol was changed to a higher SA preparation were compared with 28 patients (high SA group) just after the switch. Injection techniques were similar in both groups: peritumoral injections at two to four points of a mixture of half-filtered (0.22 microm filter) and unfiltered Tc-99m sulfur colloid in 6 ml followed immediately by intradermal injections of filtered sulfur colloid above the tumor. Activity levels for both types of injections ranged from 3.7 to 11.1 mBq (100 to 300 microCi). Preparation of the higher SA mixture of sulfur colloid was achieved by using only one eighth of the sulfur colloid vial contents when the same activity (125 mCi) of Tc-99 was added. Regions of interest were drawn around the images of sentinel nodes and the initial injection site in the anterior and lateral projections. Ratios of sentinel node to initial injection site count were calculated for both groups. RESULTS: The mean ratio of sentinel node to injection site count in the high SA group was 2.9 times greater than that in the low SA group. The median ratio value was 2.7 times greater in the high SA group. CONCLUSION: These preliminary results suggest higher counts in the sentinel node are possible with a higher SA preparation.

Breast Neoplasms↗
PubMed2002

The efficacy of sestamibi parathyroid scintigraphy for directing surgical approaches based on modified interpretation criteria.

PURPOSE: With the increasing use of targeted parathyroidectomy, the accuracy of sestamibi parathyroid scintigraphy (SPS) in determining the best surgical approach has become more clinically relevant than its sensitivity for detecting all abnormal glands. The reported accuracy of SPS does not represent the true efficacy of SPS for directing targeted parathyroidectomy, because many authors reported accuracy on the basis of abnormal glands. The authors assessed the efficacy of SPS based on modified interpretation criteria to determine specifically whether SPS influences the surgeon's choice of a targeted versus a conventional approach to parathyroidectomy. METHODS: The authors reviewed the SPS studies (both dual-isotope subtraction and Tc-99m sestamibi dual-phase techniques) performed in 80 patients with primary hyperparathyroidism. All patients had surgery with histologic diagnoses, intraoperative PTH assays, and clinical follow-up. RESULTS: Of 75 patients with solitary adenomas, 9 SPS studies were negative, equivocal, or showed two or more foci, and 66 studies showed a solitary focus on the correct side. Of these 66 studies, 63 showed a lesion in the correct quadrant (e.g., superior or inferior) and 3 predicted the correct side only but a wrong quadrant. The positive-predictive value of SPS was 100% for correctly identifying the side of the adenoma (thus correctly directing unilateral surgery) and 95.5% for correctly identifying the quadrant of the solitary adenoma. CONCLUSION: The positive-predictive value of SPS for directing the surgical approach (but not for detecting individual lesions) that reveals a single focus is very high based on our modified interpretation criteria.

Adenoma↗
PubMedDate not supplied

Clinical breast lymphoscintigraphy: optimal techniques for performing studies, image atlas, and analysis of images.

Breast lymphoscintigraphy is increasingly performed before surgery to delineate the drainage to the sentinel node (SN) in the axilla. On the basis of the histologic status of harvested SNs, the disease status of the entire axilla can be predicted. This prediction allows a more limited dissection to be performed while maintaining staging accuracy comparable with that of classic axillary lymph node dissection. Lymphoscintigraphy assists surgeons in harvesting the SN during gamma probe-assisted axillary biopsy or dissection and provides a wide field of view survey, among other benefits. When certain injection protocols are used, lymphoscintigraphy can be performed in the afternoon before surgery the next morning, thus minimizing disruptions of tight surgical schedules. Image acquisition can be optimized and SN activity can be maximized by means of such factors as parameters for preparation of the radiotracer, injection techniques, energy settings for the gamma camera, breast displacement maneuvers, and techniques for marking and outlining the patient's body. The ultimate goals are to delineate the true SN, maximize activity in the node for facilitated removal (even at next-day surgery), and deliver the information to the surgeon without delaying the surgical schedule.

Artifacts↗