Kutlan Ozker

Evaluation of Photodynamic Therapy near Functional Brain Tissue in Patients with Recurrent Brain Tumors

AbstractIntroduction: Photodynamic therapy (PDT) involves the selective retention of a photosensitizer that upon activation with light mediates tumor cell destruction via the production of singlet oxygen. This study evaluates the toxicity of PDT and a new light-delivery device based on light-emitting diode (LED) technology in selected patients with brain tumors. Methods: Twenty patients with recurrent malignant brain tumors received 22 treatments with PDT. Sixteen tumors were supratentorial and four tumors were infratentorial. Patients received IV Photofrin® 24 h prior to light exposure starting at 0.75 mg kg-1. Laser and LED arrays were used to deliver 100 J cm-2 of light to the sensitized tumors. Fourteen patients received PDT with a laser-balloon adapter, two via interstitial optical fibers and five patients had LED based PDT. At the maximum Photofrin® dose of 2.0 mg kg-1 five patients received laser-balloon adapter light and five patients received LED light. In addition, three patients received LED light with 0.25 mg kg-1 of Visudine®, a benzoporphyrin derivative (BPD). Quantitative analysis of toxicity and time to progression was performed. Results: Two patients had toxicity consisting of ataxia and facial weakness after treatment with interstitial fibers. Escalating doses of Photofrin® were tolerated to the maximum dose of 2.0 mg kg-1. BPD did not result in additional toxicity. PDT in the posterior fossa or near eloquent brain was tolerated using the LED or laser-balloon adapter. All patients had tumor responses as documented by MRI scan and the mean time to tumor progression after PDT was 67 weeks. Conclusion: PDT with LED balloon adapters (also tunable dye laser) has acceptable toxicity in brain tumor patients. Future studies using more effective photosensitizers could improve local recurrence control.

In-111 WBC imaging of osteomyelitis in patients with underlying bone scan abnormalities

One hundred seven combined In-111 WBC/Tc-99m MDP scans performed on 87 patients with a high clinical suspicion of osteomyelitis were retrospectively reviewed. An 86% sensitivity and a 94% specificity for detecting osteomyelitis were found. In addition, patients were grouped into one of five clinical settings for more detailed analysis: diabetic osteoarthropathy, previous arthroplasty, fracture, overlying skin ulcer, and other etiology. Forty-seven studies were performed while patients received antibiotic therapy without loss of sensitivity for detecting osteomyelitis. Results obtained with scintigraphy compared favorably to other imaging and laboratory studies used to detect osteomyelitis. In conclusion, the combined In-111 WBC/Tc-99m MDP scan is a very sensitive and specific method to detect osteomyelitis in patients with concurrent diabetic osteoarthropathy, fracture, postoperative healing, and overlying skin ulcer. Antibiotic treatment does not appear to adversely affect the sensitivity of these scans.

Correlation of technetium-99m MIBI and thallium-201 retention in solitary cold thyroid nodules with postoperative histopathology

Abstract.A comparative prospective study of technetium-99m methoxyisobutylisonitrile (MIBI) and thallium-201 with early (15 min) and delayed (90 min for MIBI, 3 h for 201Tl) imaging in the differentiation of thyroid lesions is presented. Forty patients with cold thyroid nodules visualised on 99mTc-pertechnetate scan and with dyskaryotic or atypical epithelial cells verified by fine-needle aspiration biopsy underwent MIBI and 201Tl scintigraphy at 3-day intervals. Subsequent thyroidectomies were carried out in all patients. Semiquantitative analysis was performed using a lesion to non-lesion ratio on early (ER) and delayed images (DR). Additionally, a retention index (RI) was calculated using the formula RI=(DR– ER) × 100/ER. The reproducibility of the method for the early and delayed measurements was tested by analysing intra- and inter-observer variability and repeatability coefficients. Histopathologically, the nodules were found to be well-differentiated thyroid cancer in 21 patients and benign in 19 patients. There was no significant difference in the ER between malignant and benign lesions for either 201Tl or MIBI (P>0.05). However, for both agents significant differences were found between malignant and benign lesions with regard to DR (P<0.01 for 201Tl and P<0.001 for MIBI) and RI (P<0.001 for both agents). Statistical comparison of the two agents showed no significant differences (P>0.05) except with regard to DR and RI in malignant nodules (P<0.05). A receiver operating characteristic analysis was performed to determine threshold levels for the differentiation of malignant from benign nodules. Following this analysis, ER, DR and RI levels of 1.03, 1.54 and 2 for MIBI and ≤1.42, 1.24 and 5 for 201Tl were selected. Using these threshold levels, the sensitivity, specificity and accuracy of the study were 90.5%, 36.8% and 65% for ER MIBI, 61.9%, 94.7% and 77.5% for DR MIBI, 95.2%, 89.4% and 92.5% for RI MIBI, 85.7%, 47.3% and 67.5% for ER 201Tl, 80.9%, 73.6% and 77.5% for DR 201Tl, and 90.5%, 94.7% and 92.5% for RI 201Tl. In conclusion, the DR for MIBI and 201Tl is superior to the ER in detecting malignant nodules, and the RI for both MIBI and 201Tl is more valuable than the DR in differentiating malignant from benign thyroid nodules.

Preclinical Evaluation of Benzoporphyrin Derivative Combined with a Light-Emitting Diode Array for Photodynamic Therapy of Brain Tumors

Objective: The aim of this study was to investigate the second-generation photosensitizer benzoporphyrin derivative (BPD) and a novel light source applicator based on light-emitting diode (LED) technology for photodynamic therapy (PDT) of brain tumors. Methods: We used a canine model to investigate normal brain stem toxicity. Twenty-one canines underwent posterior fossa craniectomies followed by PDT with BPD. These animals were compared to light only and BPD control. In addition, we investigated the ability of BPD and LED to cause inhibition of cell growth in canine glioma and human glioma cell lines, in vitro. The biodistribution of BPD labeled with 111In-BPD in mice with subcutaneous and intracerebral gliomas and canines with brain tumors was studied. Results: The in vivo canine study resulted in a maximal tolerated dose of 0.75 mg/kg of BPD and 100 J/cm2 of LED light for normal brain tissue. The in vitro study demonstrated 50% growth inhibition for canine and human glioma cell lines of 10 and 4 ng/ml, respectively. The mucine study using 111In-BPD showed a tumor to normal tissue ratio of 12:1 for intracerebral tumors and 3.3:1 for subcutaneous tumors. Nuclear scans of canines with brain tumors showed uptake into tumors to be maximal from 3 to 5 h. Conclusion: Our study supports that BPD and LED light sources when used at appropriate drug and light doses limit normal brain tissue toxicity at doses that can cause significant glioma cell toxicity in vitro. In addition, there is higher BPD uptake in brain tumors as compared to normal brain in a mouse glioma model. These findings make BPD a potential new-generation photosensitizer for the treatment of childhood posterior fossa tumors as well as other malignant cerebral pathology.

Technetium-99m sestamibi uptake in human breast carcinoma cell lines displaying glutathione-associated drug-resistance

An in vitro study was designed to evaluate the uptake of sestamibi (MIBI) in P-glycoprotein (Pgp) and glutathione-associated (GSH) multidrug-resistant (MDR) cell lines. MIBI uptake was studied in various human breast carcinoma cell lines, i.e. in wild-type (MCF7/wt) cells, in adriamycin-resistant (MCF7/adr) cells which express Pgp and in melphalan-resistant (MCF7/mph) cells with increased levels of GSH. The effects of buthiomine sulphoximine (BSO) and verapamil on MIBI uptake were also studied in the MCF7/mph and MCF7/adr cells respectively. The cells were incubated for 1 h with a dose of 0.1 MBq thallium-201 and technetium-99m MIBI. Both MIBI and201Tl uptakes were higher for MCF7/mph cells than for the other cells studied. The mean MIBI uptake in MCF7/adr cells was significantly lower than that in MCF7/wt cells (1.9%±0.5% vs 3.1%.0.6%;P <0.01). Verapamil treatment increased the MIBI uptake in MCF7/adr cells (to 2.6%.0.3%;P <0.05). Treatment of MCF7/mph cells with BSO resulted in a significant reduction in GSH content (from 243.2±81.1 nmoUmg protein to 17.6±4.4 nmol/mg protein;P <0.001). However, MIBI uptake in BSO-treated and untreated MCF7/mph cells was similar (4.43%±0.5% and 5.93%±1.7%, respectively;P >0.1). This study suggests that the uptake of MIBI is not diminished by glutathione-associated drug resistance and that MIBI uptake in a tumour sample does not necessarily indicate that a cancer is sensitive to drugs.

Selective incorporation of111In-labeled PHOTOFRIN™ by glioma tissuein vivo

The use of PHOTOFRIN™ for photodynamic therapy of human gliomas has been studied by i.v. administration and laser photosensitization. Defining the uptake of PHOTOFRIN™ in the patients tumor in comparison with the surrounding normal brain tissue is highly desirable for patient selection and study ofin vivo kinetics. We utilized a non-invasive approach to the detection of PHOTOFRIN™ uptake in brain tumors with111In-oxine radiolabeled PHOTOFRIN™ and external imaging and quantitation using a gamma camera. Biodistribution of111In-labeled PHOTOFRIN™ in 13 organs was determined in four dogs and 15 mice with gliomas.99mTc-DTPA was used as a control for nonspecific uptake. The greatest concentration of111In-PHOTOFRIN™ in the brain tumor occurred at 24 hours post i.v. administration. The brain tumor PHOTOFRIN™ uptake was seven times greater than that of normal brain. The decreased blood background at 72 hours made this the optimum time for imaging. Specific tumor tissue uptake of111In-PHOTOFRIN™ occurred, well beyond that resulting from blood-brain-barrier (BBB) breakdown.

Biodistribution of 99Tcm-labelled 5-thio-D-glucose.

We studied the biodistribution and tumour localization of 99Tcm-labelled-5-thio-D-glucose (99Tcm-TG). 5-Thio-D-glucose was labelled with 99Tcm by direct stannous ion reduction. The biodistribution of 99Tcm-TG was investigated in normal rabbits and in mice bearing experimental tumours. In rabbits, the plasma and clearance of 99Tcm-TG was 14.5 +/- 2.0 and 11.3 +/- 3.0 ml.min-1 respectively. Urinary excretion at 1 h was 53 +/- 5%. 99Tcm-TG was injected intravenously in mice bearing MC26 colon carcinoma and tissue samples were analysed by gamma scintillation counting at various times. Uptake of 99Tcm-TG in tumour at 1 and 3 h was 1.6 +/- 0.3% and 1.2 +/- 0.3%; the tumour to muscle ratios were 2.7:1 and 4:1 respectively. The autoradiographic biodistribution of 99Tcm-TG in MX-1 human breast xenografted nude mice showed more persistent tumour uptake of 99Tcm-TG than 14C-2-deoxyglucose (14C-DG). 99Tcm-TG accumulated in the centre of the tumours; 14C-DG was decreased in this central region probably because of zones of infarction on necrosis. The discordance between the tumour uptake of 99Tcm-TG and 14C-DG indicates that 99Tcm-TG does not act like a glucose analog, suggesting 99Tcm-TG avidity for zones of infarction or necrosis. The further study of 99Tcm-TG in tumours and ischaemic injury is warranted.

99mTc-gentamicin: Chemical and biological evaluation

Abstract99mTc-Gentamicin complex, a new agent for renal studies, is prepared by the reduction of pertechnetate by stannous chloride. Organ distribution in rats and paper chromatography with Whatman 3MM paper [developed in n-butanol, acetic acid, and water (4:1:1)] were favored as analytical tools for determination of labeling parameters of 99mTc-Gentamicin. A higher concentration of stannous ion is responsible for the formation of insoluble technetium species which concentrate in the liver. The mean kidney: liver ratio of 10.4:1 was obtained 1 h after injection. This confirms that scintigraphic delineation of kidneys is highly satisfactory.

Evaluation of 99Tcm-bicisate as a renal imaging agent

99Tcm-bicisate (99Tcm-ECD), often used as a brain perfusion agent, is rapidly converted following intravenous injection to the polar monoacid (99Tcm-ECM) and diacid (99Tcm-EC) metabolites. Such polar metabolites, which are eliminated principally by renal clearance, are potential renal imaging agents. In this study, 99Tcm-ECD was compared for the first time with 99Tcm-EC, 99Tcm-mercaptoacetyltriglycine (99Tcm-MAG3) and 131I-orthoiodohippurate (OIH) as renal imaging agents in rabbits. Whole-body images and renograms were obtained for all three of the 99Tcm agents, and pharmacokinetic parameters including plasma and urinary clearance were studied for all four agents. The plasma clearance of 99Tcm-EC (37 ml min-1) was slower than that of 99Tcm-ECD (51 ml min-1), which could be accounted for by the higher liver uptake of 99Tcm-ECD. The urinary clearance of 99Tcm-ECD (35 ml min-1), 99Tcm-EC (34 ml min-1) and 99Tcm-MAG3 (39 ml min-1) was similar. The renal images obtained with 99Tcm-ECD were comparable to those for 99Tcm-MAG3 and 99Tcm-EC. However, liver uptake was more prominent with 99Tcm-ECD than with the other agents. The 99Tcm-ECD renogram curves showed a prolonged decrease in renal activity compared to both 99Tcm-EC and 99Tcm-MAG3. In potential human studies, the relatively high liver uptake of 99Tcm-ECD superimposed on right renal activity may be a limitation. Therefore, we conclude that 99Tcm-ECD is less favourable when compared to existing renal agents due to its high extrarenal uptake and renal kinetics.

A consensus for the minimum requirements of a blood cell radiolabeling facility.

Dear Sir, There are significant variations, worldwide, in the design, conditions, and regulations of blood cell radiolabeling facilities. Improving and standardizing the radiopharmacy practice related to blood cell labeling is critical to safety and efficacy of the radiolabeled blood cells which are prepared on a daily basis and administered to a large number of patients. Establishing adequate conditions, or at least the minimum requirements, for the cell labeling facilities and clinical radiopharmacies would help to substantially reduce the risks associated with radiolabeling and administration of these cells. Of course it is strongly recommended to build further on these minimum requirements, gradually upgrading the practice to the ideal conditions. Furthermore, it is important to bear in mind that the legislations at the national and/or regional level take precedence over the recommendations of societies and/or organizations. During the 14th Congress of the International Society of Radiolabeled Blood Elements, which took place 26–29March, 2009 in Antalya, Turkey, there was an international panel discussion on “Update on Design, Requirements and Regulations of a Radiopharmacy Facility in Relation to a Cell Labeling Facility”. That session was the genesis of a consensus statement about the minimum requirements necessary for a blood cell radiolabeling facility. This letter presents the consensus recommendation developed by the participants in that session. Minimum requirements for the facility: All procedures for radiolabeling blood cells are to be performed in an ISO class 5 (grade A or old class 100) environment using a laminar airflow workbench (LAFW) Ideally the area surrounding the location (buffer area) where the radiolabeling of blood cells is conducted should meet an ISO class 7 level (grade C or old class 10,000) of cleanliness. However, if an ISO class 7 buffer area is not available, a clean-restricted (segregated) area must be used as the buffer area. The ISO class 5 LAFW and the surrounding segregated area must be dedicated to radiolabeling of blood cells. Ideally a refrigerated centrifuge equipped with sealable buckets dedicated to radiolabeling of blood cells must also be located in the segregated area. If a refrigerated centrifuge is not available a non-refrigerated centrifuge can be used, provided that leukocyte and platelet sediment Eur J Nucl Med Mol Imaging (2009) 36:1351–1352 DOI 10.1007/s00259-009-1187-9