Pinhole micro-SPECT/CT for noninvasive monitoring and quantitation of oncolytic virus dispersion and percent infection in solid tumors.

The purpose of our study was to validate the ability of pinhole micro-single-photon emission computed tomography/computed tomography (SPECT/CT) to: 1) accurately resolve the intratumoral dispersion pattern and 2) quantify the infection percentage in solid tumors of an oncolytic measles virus encoding the human sodium iodide symporter (MV-NIS). Sodium iodide symporter (NIS) RNA level and dispersion pattern were determined in control and MV-NIS-infected BxPC-3 pancreatic tumor cells and mouse xenografts using quantitative, real-time, reverse transcriptase, polymerase chain reaction, autoradiography and immunohistochemistry (IHC). Mice with BxPC-3 xenografts were imaged with (123)I or (99)TcO(4) micro-SPECT/CT. Tumor dimensions and radionuclide localization were determined with imaging software. Linear regression and correlation analyses were performed to determine the relationship between tumor infection percentage and radionuclide uptake (% injected dose per gram) above background and a highly significant correlation was observed (r(2)=0.947). A detection threshold of 1.5-fold above the control tumor uptake (background) yielded a sensitivity of 2.7% MV-NIS-infected tumor cells. We reliably resolved multiple distinct intratumoral zones of infection from non-infected regions. Pinhole micro-SPECT/CT imaging using the NIS reporter demonstrated precise localization and quantitation of oncolytic MV-NIS infection, and can replace more time-consuming and expensive analyses (for example, autoradiography and IHC) that require animal killing.

Potential for contamination during removal of radioactive seeds from surgically excised tissue.

The purpose of this study was to determine whether the use of a scalpel or electrocautery to remove radioactive sealed sources ("seeds") from surgically excised tissue could damage the seed and cause it to leak its radioactive contents. Attempts were made to cut or burn Oncura Model 6711 non-radioactive seeds while in pig muscle or on a stainless steel plate. Additionally, one active 125I seed was purposely charred using pressure with an electrocautery knife to see whether the casing could be damaged. Electron microscopy scanning was performed on the dummy seeds to determine if the integrity of the metal casing had been compromised. Two types of leak tests were performed on the active seed to verify the presence or absence of loose contamination. The seed casing was not damaged from either use of a scalpel or electrocautery when the seed was in tissue. The active seed was not found to be leaking after applying pressure with an electrocautery knife while the seed was on a stainless steel plate. We conclude that removal of active Model 6711 seeds from surgically excised tissue can be done safely with a scalpel or electrocautery because constant, firm pressure cannot be applied to the seed. This is likely true for seeds made of similar materials.

Benefits and safety of CT fluoroscopy in interventional radiologic procedures.

PURPOSE: To determine the benefits and safety of computed tomographic (CT) fluoroscopy when compared with conventional CT for the guidance of interventional radiologic procedures. MATERIALS AND METHODS: Data on 203 consecutive percutaneous interventional procedures performed with use of CT fluoroscopic guidance and 99 consecutive procedures with conventional CT guidance were obtained from a questionnaire completed by the radiologists and CT technologists who performed the procedures. The questionnaire specifically addressed radiation dose measurements to patients and personnel, total procedure time, total CT fluoroscopy time, mode of CT fluoroscopic guidance (continuous versus intermittent), success of procedure, major complications, type of procedure (biopsy, aspiration, or drainage), site of procedure, and level of operator experience. RESULTS: The median calculated patient absorbed dose per procedure and the median procedure time with CT fluoroscopy were 94% less and 32% less, respectively, than those measurements with conventional CT scanning (P <.05). An intermittent mode of image acquisition was used in 97% of the 203 cases. This resulted in personnel radiation dosimetric readings below measurable levels in all cases. CONCLUSION: As implemented at the authors' institution, use of CT fluoroscopy for the guidance of interventional radiologic procedures markedly decreased patient radiation dose and total procedure time compared with use of conventional CT guidance.

Bracket positioning and resets: five steps to align crowns and roots consistently.

Orthodontists strive for accurate bracket positioning because it makes achieving a superior occlusion easier. Whether one uses a direct or an indirect bonding technique, the initial appliance placement typically includes some bracket-positioning errors. The clinician either corrects these errors during treatment or tediously repeats archwire bends to compensate for the misplaced brackets. The clinician should assess bracket positioning early in treatment by clinical and radiographic evaluations and then correct all positioning errors during a single dedicated reset appointment. This article describes a 5-step protocol for assessing and correcting bracket-positioning errors.

Pancreatic cystic neoplasms: the role and sensitivity of needle aspiration and biopsy.

BACKGROUND: The proper evaluation of patients with pancreatic cystic neoplasms remains controversial. Although computed tomography (CT) and sonography can differentiate the majority of these tumors, needle aspiration and biopsy can be helpful in selected patients. The purpose of this study was to (1) determine the sensitivity of needle aspiration and biopsy of cystic pancreatic neoplasms, (2) assess the complications after needle aspiration and biopsy, and (3) assess the indications for needle aspiration and biopsy by using the radiographic appearance as a guide. METHODS: The histories, imaging studies, and pathologic specimens of 18 patients with serous cystadenoma (10 patients) or mucinous cystic tumor (eight patients) of the pancreas who also underwent CT-guided (n = 16), sonographically guided (n = 3), or intraoperative (n = 4) needle biopsy (n = 23 total biopsies) between 1976 and 1996 were retrospectively reviewed. RESULTS: The histologic diagnosis of the serous subtype was made with needle aspiration and biopsy in five of 10 patients with serous cystadenoma. The histologic diagnosis of the mucinous subtype was made with needle aspiration and biopsy in six of eight patients with mucinous cystic neoplasms. Of the 23 biopsies performed, one patient experienced significant intraperitoneal hemorrhage. Indications for needle biopsy include an atypical cystic mass on diagnostic imaging studies, confirmation of a serous cystadenoma before observation, and confirmation of mucinous cystadenocarcinoma in patients with nonresectable disease. CONCLUSION: Needle biopsy and aspiration is a helpful and safe procedure to aid in the diagnosis of cystic pancreatic neoplasms before surgery.