Preliminary PET/CT Imaging with Somatostatin Analogs [<Superscript>68</Superscript>Ga]DOTAGA-TATE and [<Superscript>68</Superscript>Ga]DOTAGA-TOC

Purpose

Somatostatin receptor positron emission tomography/X-ray computed tomography (SSTR-PET/CT) is a well-established technique for staging and detection of neuroendocrine tumors (NETs). Ga-68-labeled DOTA-conjugated octreotide analogs are the privileged radiotracers for diagnosis and therapeutic monitoring of NETs. Hence, we were interested in assessing the influence of promising, newer variant DOTAGA on the hydrophilicity, pharmacokinetics, and lesion pick-up of somatostatin analogs. Herein, the potential of ([⁶⁸Ga]DOTAGA, Tyr³, Thr⁸) octreotide ([⁶⁸Ga]DOTAGA-TATE) and ([⁶⁸Ga]DOTAGA, Tyr³) octreotide ([⁶⁸Ga]DOTAGA-TOC) as NET imaging agents has been investigated.

Procedures

Amenability of [⁶⁸Ga]DOTAGA-(TATE/TOC) to kit-type formulation has been demonstrated. Biodistribution studies were carried out in normal rats at 1 h post-injection (p.i.). [⁶⁸Ga]DOTAGA-(TATE/TOC) PET/CT scans were carried out in patients (70–170 MBq, 1 h p.i.) with histologically confirmed well-differentiated NETs.

Results

[⁶⁸Ga]DOTAGA-TATE exhibited hydrophilicity similar to [⁶⁸Ga]DOTA-TATE (log P = ?3.51 vs ?3.69) whereas [⁶⁸Ga]DOTAGA-TOC was more hydrophilic than [⁶⁸Ga]DOTA-TOC (log P = ?3.27 vs ?2.93). [⁶⁸Ga]DOTAGA-TATE and [⁶⁸Ga]DOTA-TATE showed almost identical blood and kidney uptake in normal rats whereas significantly fast clearance (p < 0.05) of [⁶⁸Ga]DOTAGA-TATE was observed from other non-specific organs (liver, lungs, spleen, intestine). [⁶⁸Ga]DOTAGA-TOC also demonstrated rapid clearance from blood and kidneys (p < 0.05) in comparison to [⁶⁸Ga]DOTA-TOC. The metastatic lesions in NET patients were well identified by [⁶⁸Ga]DOTAGA-TATE and [⁶⁸Ga]DOTAGA-TOC.

Conclusion

The phenomenal analogy was observed between [⁶⁸Ga]DOTAGA-TATE and [⁶⁸Ga]DOTA-TATE as well as between [⁶⁸Ga]DOTAGA-TOC and [⁶⁸Ga]DOTA-TOC in biodistribution studies in rats. The good lesion detection ability of the two radiotracers indicates their potential as NET imaging radiotracers.

     

Assessing Glomerular Filtration in Small Animals Using [<Superscript>68</Superscript>Ga]DTPA and [<Superscript>68</Superscript>Ga]EDTA with PET Imaging

Purpose

Determining the glomerular filtration rate (GFR) is essential for clinical medicine but also for pre-clinical animal studies. Functional imaging using positron emission tomography (PET) allows repetitive almost non-invasive measurements. The aim of the study was the development and evaluation of easily synthesizable PET tracers for GFR measurements in small animals.

Procedures

Diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA) were labeled with Ga-68. The binding to blood cells and plasma proteins was tested in vitro. The distribution of the tracers in rats was analyzed by PET imaging and ex vivo measurements. From the time-activity-curve of the blood compartment (heart) and the total tracer mass excreted by the kidney, the GFR was calculated. These values were compared directly with the inulin clearance in the same animals.

Results

Both tracers did not bind to blood cells. [⁶⁸Ga]DPTA but not [⁶⁸Ga]EDTA showed strong binding to plasma proteins. For this reason, [⁶⁸Ga]DPTA stayed much longer in the blood and only 30 % of the injected dose was eliminated by the kidney within 60 min whereas the excretion of [⁶⁸Ga]EDTA was 89 ± 1 %. The calculated GFR using [⁶⁸Ga]EDTA was comparable to the measured inulin clearance in the same animal. Using [⁶⁸Ga]-DPTA, the measurements led to values which were 80 % below the normal GFR. The results also revealed that definition of the volume of interest for the blood compartment affects the calculation and may lead to a slight overestimation of the GFR.

Conclusions

[⁶⁸Ga]EDTA is a suitable tracer for GFR calculation from PET imaging in small animals. It is easy to be labeled, and the results are in good accordance with the inulin clearance. [⁶⁸Ga]DTPA led to a marked underestimation of GFR due to its strong binding to plasma proteins and is therefore not an appropriate tracer for GFR measurements.

     

Not <Emphasis Type="Italic">if</Emphasis> but <Emphasis Type="Italic">when</Emphasis>; no longer <Emphasis Type="Italic">why</Emphasis> but <Emphasis Type="Italic">how</Emphasis>

There is accruing evidence that information technology can improve patient health care, with several trials of technology showing smaller numbers of medication errors, or can provide earlier detection of adverse events. Critics of this type of research point out that better resolution of events is of no value unless their direct management influences clinical outcome. Nevertheless, indirect evidence is available, such as reports indicating the importance of providing specialist neuro-critical care in the management of patients with traumatic brain injury. These studies do not indicate which aspects of critical care management are crucial, but management aimed at the earlier detection and treatment of adverse events must be partly responsible. We continue to hope for definitive controlled trial evidence that information technology-led management yields improved patient outcome, but our experience so far of funding and conducting such studies has been poor. There is no question that we need better monitoring and event detection technology for health care and that we need more research into optimising that technology, but should their adoption depend on large-scale clinical trials? Perhaps now the questions we need to focus upon are no longer if but when, and no longer why but how.     

PET Imaging with <Emphasis Type="Italic">S</Emphasis>-[<Superscript>11</Superscript>C]Methyl-L-Cysteine and L-[<Emphasis Type="Italic">Methyl</Emphasis>-<Superscript>11</Superscript>C]Methionine in Rat Models of Glioma,Glioma Radiotherapy,and Neuroinflammation

Purpose

S-[¹¹C]-methyl-L-cysteine ([¹¹C]MCYS) has been claimed to offer higher tumor selectivity than L-[methyl- ¹¹C]methionine ([¹¹C]MET). We examined this claim in animal models.

Procedures

Rats with implanted untreated (n = 10) or irradiated (n = 7, 1 × 25 Gy, on day 8) orthotopic gliomas were scanned after 6, 9, and 12 days, using positron emission tomography. Rats with striatal injections of saline (n = 9) or bacterial lipopolysaccharide (n = 9) were scanned after 3 days.

Results

Uptake of the two tracers in untreated gliomas was similar. [¹¹C]MCYS was not accumulated in salivary glands, nasal epithelium, and healing wounds, in contrast to [¹¹C]MET, but showed 40 % higher accumulation in the healthy brain. Both tracers showed a reduced tumor uptake 4 days after irradiation and minor accumulation in inflamed striatum. [¹¹C]MCYS indicated higher lesion volumes than [¹¹C]MET (untreated tumor + 47 %; irradiated tumor up to + 500 %; LPS-inflamed striatum + 240 %).

Conclusions

[¹¹C]MCYS was less accumulated in some non-tumor tissues than [¹¹C]MET, but showed lower tumor-to-brain contrast.

     

A Feasibility Study Showing [<Superscript>68</Superscript>Ga]Citrate PET Detects Prostate Cancer

Purpose

The management of advanced or recurrent prostate cancer is limited in part by the lack of effective imaging agents. Metabolic changes in prostate cancer have previously been exploited for imaging, culminating in the recent US FDA approval of [¹¹C]choline for the detection of subclinical recurrent disease after definitive local therapy. Despite this milestone, production of [¹¹C]choline requires an on-site cyclotron, limiting the scope of medical centers at which this scan can be offered. In this pilot study, we tested whether prostate cancer could be imaged with positron emission tomography (PET) using [⁶⁸Ga]citrate, a radiotracer that targets iron metabolism but is produced without a cyclotron.

Procedures

Eight patients with castrate-resistant prostate cancer were enrolled in this single-center feasibility study. All patients had evidence of metastatic disease by standard of care imaging [X-ray computed tomography (CT), bone scan, or magnetic resonance imaging (MRI)] prior to PET with [⁶⁸Ga]citrate. Patients were intravenously injected with increasing doses of [⁶⁸Ga]citrate (136.9 to a maximum of 259 MBq). Uptake time was steadily increased from 1 h to approximately 3.5 h for the final 4 patients, and all patients were imaged with a PET/MRI. Qualitative and semi-quantitative (maximum standardized uptake value (SUV_max)) assessment of the metastatic lesions was performed and compared to the standard of care imaging.

Results

At 1- and 2-h imaging times post injection, there were no detectable lesions with [⁶⁸Ga]citrate PET. At 3- to 4-h uptake time, there were a total of 71 [⁶⁸Ga]citrate-positive lesions (67 osseous, 1 liver, and 3 lymph node). Of these, 65 lesions were visible on the standard of care imaging (CT and/or bone scan). One PET-avid osseous vertebral body metastasis was not apparent on either CT or bone scan. Twenty-five lesions were not PET-avid but seen on CT and bone scan (17 bone, 6 lymph node, 1 pleural, and 1 liver). The average of the maximum SUVs for bone or soft tissue metastases for patients treated at higher doses and uptake time was statistically higher than the corresponding parameter in normal liver, muscle, and bone. Visually obvious blood pool activity was observed even 3–4 h post injection, suggesting that further optimization of the [⁶⁸Ga]citrate imaging protocol is required to maximize signal-to-background ratios.

Conclusions

Our preliminary results support that PET with [⁶⁸Ga]citrate may be a novel tool for imaging prostate cancer. Future studies are needed to determine the optimal imaging protocol, the clinical significance of [⁶⁸Ga]citrate uptake, and its role in therapeutic decisions.

     

Motion-Artifact-Free <Emphasis Type="Italic">In Vivo</Emphasis> Imaging Utilizing Narcotized Avian Embryos <Emphasis Type="Italic">In Ovo</Emphasis>

Purpose  

The chick embryo in ovo is a well-accessible and economical in vivo model, but its use in molecular imaging has been limited because of motion artifacts on resulting images. The purpose of this study was to develop a method using narcotics to inhibit motility and to perform motion-artifact-free imaging of living chick embryos in ovo.     

Molecular Authentication of Medicinal Plant, <Emphasis Type="Italic">Swertia</Emphasis><Emphasis Type="Italic">chirayita</Emphasis> and its Adulterant Species

Swertia is ethno-medicinally an important genus belonging to family Gentianaceae. Swertia chirayita is used as imperative medicinal plant in Indian system of medicine. However, this species has been frequently adulterated due to its high demand and scarcity. Authentication of this species was needed to protect consumers and conservation measures and to find out the alternative source. Deoxyribose nucleic acid (DNA) extracted from fifteen samples of six species belonging to different localities, were used as templates. Four candidate barcodes were amplified by polymerase chain reaction and sequence analysis was executed by Z-Big Dye Terminator Cycle Sequencing v.3. Sequenced products were analyzed on automated applied biosystems 3730XI analyzer. Identification was performed by using molecular evolutionary genetics analysis 5 software (version 5.1). The amplification efficiency of all DNA barcodes [megakaryocyte-associated tyrosine kinase (matK), ribulose-bisphosphate carboxylase (rbcL), photosystem II protein D1- stuctural RNA- His tRNA (psbA-trnH) and internal transcribed spacer region (ITS)] was 100 %. Here, the highest interspecific divergence provided by ITS is 11.87 % and intraspecific by psbA-trnH being 10.22 % as compared to matK (5.04 %) and rbcL (0.99 %). ITS region proves robust molecular marker for differing the S. chirayita from its related adulterant species. All barcoding regions indicate that S. chirayita and S. minor both are more closely related than other Swertia species. Findings showed that DNA barcoding is an efficient tool for identification and authentication of S. chirayita. Use of S. minor as substitute to S. chirayita can be advocated.     

DNA Barcodes Distinguish <Emphasis Type="Italic">Withania somnifera</Emphasis> and <Emphasis Type="Italic">Withania ashwagandha</Emphasis>

On the basis of morphology, chemical profiling, crossing ability, amplified fragment length polymorphism and comparison of nucleotide sequences of nuclear ribosomal internal transcribed spacer (ITS), the cultivated form of Withania somnifera, a species of therapeutic value, has been circumscribed as a new species, Withania ashwagandha. The present study was undertaken to ascertain whether the two species can be distinguished on the basis of DNA barcoding. Six barcode loci, ITS, ITS2, matK (maturase K), rbcL (ribulose-bisphosphate carboxylase/oxygenase, large subunit), rpoC1 (RNA polymerase-β′ subunit, main catalytic subunit) and trnH-psbA spacer (transfer RNA for histidine-photosystem II protein D1 spacer) from W. somnifera, W. ashwagandha, their hybrid, and ‘ashwagandha’ market samples were amplified, sequenced, and compared. ITS, ITS2 and matK distinguished two species on the basis of phylogenetic tree method. Likewise, BLAST 1 analysis based on ITS, ITS2, matK, and rbcL individually discriminated two species. However, on the basis of Kimura 2 Parameter distances, two species could not be distinguished as the requirement of a distinct barcode gap—the highest intraspecific distance being lower than the lowest interspecific distance—was not met by any of the loci. If compared by character-based method, ITS, ITS2 and matK sequences of the two species had distinct diagnostic nucleotides (pure character attributes) at nine, four and one positions, respectively. Interestingly, all market samples co-segregated and shared character attributes with W. ashwagandha.     

<Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Vivo</Emphasis> Comparison of Selected Ga-68 and Zr-89 Labelled Siderophores

Purpose

Some [⁶⁸Ga]siderophores show promise in specific and sensitive imaging of infection. Here, we compare the in vitro and in vivo behaviour of selected Ga-68 and Zr-89 labelled siderophores.

Procedures

Radiolabelling was performed in HEPES or sodium acetate buffer systems. Radiochemical purity of labelled siderophores was determined using chromatography. Partition coefficients, in vitro stability and protein binding affinities were determined. Ex vivo biodistribution and animal imaging was studied in mice.

Results

Certain differences among studied siderophores were observed in labelling efficiency. Protein binding and stability tests showed highest stabilities and lowest protein binding affinities for Ga-68 and [⁸⁹Zr]triacetylfusarinine C (TAFC). All studied Ga-68 and [⁸⁹Zr]siderophores exhibited a similar biodistribution and pharmacokinetics in mice with the exception of [⁸⁹Zr]ferrioxamine E (FOXE).

Conclusions

Zr-89 and [⁶⁸Ga]siderophores showed analogous in vitro and in vivo behaviour. Tested [⁸⁹Zr]siderophores could be applied for longitudinal positron emission tomography (PET) studies of fungal infections and especially TAFC for the development of novel bioconjugates.

     

Synthesis and <Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Vivo</Emphasis> Evaluation of [<Superscript>3</Superscript>H]LRRK2-IN-1 as a Novel Radioligand for LRRK2

Purpose

LRRK2 (leucine-rich repeat kinase 2) has recently been proven to be a promising drug target for Parkinson’s disease (PD) due to an apparent enhanced activity caused by mutations associated with familial PD. To date, there have been no reports in which a LRRK2 inhibitor has been radiolabeled and used for in in vitro or in vivo studies of LRRK2. In the present study, we radiolabeled the LRRK2 ligand, LRRK-IN-1, for the purposes of performing in vitro (IC₅₀, K _d , B _max, autoradiography) and in vivo (biodistribution, and blocking experiments) evaluations in rodents and human striatum tissues.

Procedures

[³H]LRRK2-IN-1 was prepared with high radiochemical purity (>99 %) and a specific activity of 41 Ci/mmol via tritium/hydrogen (T/H) exchange using Crabtree’s catalyst. For IC⁵⁰, K _d , and B _max determination, LRRK2-IN-1 was used as a competing drug for nonspecific binding assessment. The specific binding of the tracer was further evaluated via an in vivo blocking study in mice with a potent LRRK2 inhibitor, Pf-06447475.

Results

In vitro binding studies demonstrated a saturable binding site for [³H]LRRK2-IN-1 in rat kidney, rat brain striatum and human brain striatum with K _d of 26 ± 3 and 43 ± 8, 48 ± 2 nM, respectively. In rat, the density of LRRK2 binding sites (B _max) was higher in kidney (6.4 ± 0.04 pmol/mg) than in brain (2.5 ± 0.03 pmol/mg), however, in human brain striatum, the B _max was 0.73 ± 0.01 pmol/mg protein. Autoradiography imaging in striatum of rat and human brain tissues gave results consistent with binding studies. In in vivo biodistribution and blocking studies in mice, co-administration with Pf-06447475 (10 mg/kg) reduced the uptake of [³H]LRRK2-IN-1 (%ID/g) by 50–60% in the kidney or brain.

Conclusion

The high LRRK2 brain density observed in our study suggests the feasibility for positron emission tomography imaging of LRRK2 (a potential target) with radioligands of higher affinity and specificity.

     

Biodistribution and Radiation Dosimetry of the <Emphasis Type="Italic">Enterobacteriaceae</Emphasis>-Specific Imaging Probe [<Superscript>18</Superscript>F]Fluorodeoxysorbitol Determined by PET/CT in Healthy Human Volunteers

Purpose

[¹⁸F]fluorodeoxysorbitol ([¹⁸F]FDS) is the first radiopharmaceutical specific for a category of bacteria and has the potential to specifically detect Enterobacteriaceae infections. The purpose of this study was to testify the safety and investigate the biodistribution and radiation dosimetry of [¹⁸F]FDS in healthy human bodies.

Procedures

Six healthy subjects were intravenously injected with 320–520 MBq [¹⁸F]FDS. On each subject, 21 whole-body emission scans and a brain scan were conducted at settled time points within the next 4 h. Residence time for each source organ was determined by multi-exponential regression. Absorbed doses for target organs and effective dose were calculated via OLINDA/EXM.

Results

No adverse events due to [¹⁸F]FDS injection were observed in the study. The tracer was cleared rapidly from the blood pool through the urinary system. A small portion was cleared into the gut through the hepatobiliary system. The effective dose (ED) was estimated to be 0.021?±?0.001 mSv/MBq. The organ receiving the highest absorbed dose was the urinary bladder wall (0.25?±?0.03 mSv/MBq).

Conclusions

[¹⁸F]FDS is safe and well tolerated. The effective dose was comparable to that of other F-18 labeled radiotracers. [¹⁸F]FDS is suitable for human use from a radiation dosimetry perspective.

     

Imaging the Dopamine System with <Emphasis Type="Italic">In Vivo</Emphasis> [<Superscript>11</Superscript>C]raclopride Displacement Studies: Understanding the True Mechanism

Measuring changes in dopamine (DA) levels in humans using radioligand-displacement studies and positron emission tomography (PET) has provided important empirical findings in diseases and normal neurophysiology. These studies are based on the assumption that DA exerts a competitive inhibition on D₂-radioligand binding. However, the transfer of this hypothesis to a proven mechanism has not been fully achieved yet and an accumulating number of studies challenge it. In addition, new evidence suggests that DA exerts a noncompetitive inhibition on D₂-radioligand binding under amphetamine conditions. This article reviews the theoretical basis for the DA competition hypothesis, the in vivo and in vitro evidences supporting a noncompetitive action of DA on D₂-radioligand binding under amphetamine conditions, and discusses possible mechanisms underlying this noncompetitive interaction. Finally, we propose that such noncompetitive interactions may have important implications for how one interprets findings obtained from radioligand-displacement PET studies in neuropsychiatric diseases, especially in schizophrenia in which a dysregulation of the DA-promoted internalization of D₂ receptors was recently suggested.     

Imaging Characteristics and First Experience of [<Superscript>68</Superscript>Ga]THP-PSMA,a Novel Probe for Rapid Kit-Based Ga-68 Labeling and PET Imaging: Comparative Analysis with [<Superscript>68</Superscript>Ga]PSMA I&amp;T

Purpose

[⁶⁸Ga]Trishydroxypyridinone (THP)–prostate-specific membrane antigen (PSMA) is a novel tracer that can be labeled in one step by cold reconstitution of a kit with unprocessed generator eluate, targeting PSMA via the lysine-urea-glutamate (KuE) motif. The aim of this study was to evaluate the human imaging characteristics of [⁶⁸Ga]THP-PSMA.

Procedures

[⁶⁸Ga]THP-PSMA positron emission tomography (PET)/x-ray computed tomography (CT) was performed in 25 patients with biochemical recurrence after radical prostatectomy for prostate cancer. Urinary and biliary excretion and tumor lesion uptake were quantified using standardized uptake values (SUVs). Imaging characteristics were assessed in terms of non-target organ uptake, background activity, target-to-background ratios (TBRs) of tumor lesions, and frequency of bladder halo artifacts. Findings were compared to a matched cohort of 25 patients undergoing PET/CT with the established agent [⁶⁸Ga]PSMA I&T.

Results

Physiologic uptake of [⁶⁸Ga]THP-PSMA was significantly lower in salivary glands (P?<?0.0001), liver (P?<?0.0001), spleen (P?<?0.0001), and kidneys (P?<?0.0001) than with [⁶⁸Ga]PSMA I&T. While biliary tracer excretion of [⁶⁸Ga]THP-PSMA was negligible, urinary tracer excretion of [⁶⁸Ga]THP-PSMA was fast, and significantly higher than for [⁶⁸Ga]PSMA I&T, contributing to a higher frequency of bladder artifacts. Malignant lesion uptake of [⁶⁸Ga]THP-PSMA assessed as either SUV or TBR was significantly lower than with [⁶⁸Ga]PSMA I&T.

Conclusion

[⁶⁸Ga]THP-PSMA yields suitable in vivo uptake characteristics. The simplified synthesis method for [⁶⁸Ga]THP-PSMA may facilitate wider application and higher patient throughput with PSMA imaging. However, direct intraindividual comparison studies are needed to assess the relative performance of [⁶⁸Ga]THP-PSMA vs other PSMA ligands in terms of clinical detection rate and image quality.

     

Evaluation of Cultivated and Wild <Emphasis Type="Italic">Allium</Emphasis> Accessions for Resistance to <Emphasis Type="Italic">Fusarium oxysporum</Emphasis> f. sp. <Emphasis Type="Italic">cepae</Emphasis>

Fusarium basal rot (FBR) caused by Fusarium oxysporum f. sp. cepae (FOC) is a highly destructive soil borne disease incurring heavy damage in pre and post harvest onion and garlic crops worldwide. Only a few onion lines exhibit partial resistance against the pathogen and there is a need for identification of more effective resistance sources for use in breeding programmes. Selected sets of wild onion and garlic accession and seven related Allium species were screened for resistance to Fusarium basal rot using three FOC isolates. FOC infection revealed significant variation among the evaluated Allium species (at P = 0.001). A. sativum accession ‘CBT-As153’ showed high level of resistance to each isolate while A. cepa accession ‘CBT-Ac77’ exhibited intermediate resistance. Among related Allium species, A. fistulosum, A. roylei and A. schoenoprasum were highly resistant, A. tuberosum had mixed response while A. griffithianum was susceptible. Further, the root density of Allium species negatively correlated with disease incidence for different FOC isolates. Thus, the present study suggests that besides related Allium species, A. sativum ‘CBT-As153’ can be used as a potential donor of FBR resistance for genetic improvement of onion and garlic in India.     

Nutritional Requirements to Improve Delta-Endotoxins Production of <Emphasis Type="Italic">Bacillus</Emphasis><Emphasis Type="Italic">thuringiensis</Emphasis> var. <Emphasis Type="Italic">kurstaki</Emphasis> Using Mixed Designs Modelling

Bacillus thuringiensis kurstaki is a soil bacterium that produces insecticidal toxins called delta-endotoxins. In order to increase the toxic crystal concentrations in a low-cost culture medium and thus improve the biopesticide quality to control insect pests, the Plackett–Burman screening method was applied. It was shown a tool to evaluate the significance of the selected seven factors (KH₂PO₄, K₂HPO₄, MgSO₄, MnSO₄, FeSO₄, soybean meal, starch) which are necessary to the production of the delta-endotoxins. This was performed into two different shake flasks (250 and 500 ml). The main factors that affected the production of delta-endotoxins are shown to be soybean meal, starch, and FeSO₄ in 250 ml culture flasks. In 500 ml culture flasks, soybean meal and FeSO₄ are the principal factors influencing the delta-endotoxin production. The multiple linear regression, a method applied as the merging dataset of the two Plackett–Burman designs, established that soybean meal and starch are the factors positively affecting the production of delta-endotoxins, in contrast to FeSO₄. Furthermore, the available oxygen in culture flasks showed no significant negative effect on delta-endotoxin production. This study revealed that mixed method designs were useful to identify the significance and the effect of hidden culture parameters.     

Larvicidal Activity of <Emphasis Type="Italic">Colocasia esculenta,Eclipta prostrata</Emphasis> and <Emphasis Type="Italic">Wrightia tinctoria</Emphasis> Leaf Extract Against <Emphasis Type="Italic">Culex quinquefasciatus</Emphasis>

Control of mosquitoes by using chemical insecticides creates several problems including development of resistance. This leads to find out alternative methods via plant products. Viewing this in mind, methanolic extracts of Colocasia esculenta, Eclipta prostrata and Wrightia tinctoria leaves were tested against II, III, IV instars and pupa of filarial vector Culex quinquefasciatus. The LC₅₀ value obtained for IV instar larvae of Cx. quinquefasciatus is 165.697 ppm for C. esculenta while it is 114.257 ppm for E. prostrata and 210.298 ppm for W. tinctoria. Of the three plants studied E. prostrata is most effective in controlling mosquito larvae than the others.     

Bioefficacy of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> (Balsamo) Vuillemin and <Emphasis Type="Italic">Lecanicillium lecanii</Emphasis> Zimmerman against <Emphasis Type="Italic">Thrips tabaci</Emphasis> Lindeman

Bioefficacy of Beauveria bassiana (Balsamo) Vuillemin and Lecanicillium lecanii Zimmerman in comparison with their commercial formulations along with standard check insecticide, Fenvalerate 20 EC were evaluated against onion thrips, Thrips tabaci Lindeman under greenhouse as well as field conditions. The results revealed that the standard check fenvalerate 20 EC @ 0.0075 % showed significantly the highest cumulative corrected mortality of 97.84 % followed by commercial formulation of B. bassiana, Myco-Jaal @ 1 × 10⁸ spores/mL which showed 80.90 % mortality. The laboratory cultured B. bassiana showed percent mortalities of 74.11, 71.69 and 78.48 % for the concentrations of 1.23 × 10⁷, 1.23 × 10⁶ and 1.23 × 10⁸ spores/mL, respectively. However, these concentrations were statistically at par on all the days of observation. Thrips mortality gradually increased with the increase in concentrations of fungal preparations and days of observations. Similar trend was also observed in L. lecanii experiment. Under field conditions, Fenvalerate 20 EC @ 0.0075 % recorded highest mortality of T. tabaci (90.10 %) followed by commercial formulation of V. lecanii (Phule Bugicide @ 2 × 108 cfu/g) with 74.90 % mortality. All the concentrations of fungal concentrations gave low mortality ranging from 9.40 to 10.10 % and 7.10 to 7.40 % at 2 days after treatment (DAT) of B. bassiana and L. lecanii, respectively. The standard check of Fenvalerate 20 EC @ 0.0075 % was highly toxic and showed significantly maximum percent reduction (90.50 %) of T. tabaci population in both the experiments. The present study clearly shows that these entomopathogens may be integrated with existing integrated pest management (IPM) practices for management of T. tabaci.     

A Novel Framework for Automated Segmentation and Labeling of Homogeneous <Emphasis Type="Italic">Versus</Emphasis> Heterogeneous Lung Tumors in [<Superscript>18</Superscript>F]FDG-PET Imaging

Purpose

Determination of intra-tumor high-uptake area using 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) positron emission tomography (PET) imaging is an important consideration for dose painting in radiation treatment applications. The aim of our study was to develop a framework towards automated segmentation and labeling of homogeneous vs. heterogeneous tumors in clinical lung [¹⁸F]FDG-PET with the capability of intra-tumor high-uptake region delineation.

Procedures

We utilized and extended a fuzzy random walk PET tumor segmentation algorithm to delineate intra-tumor high-uptake areas. Tumor textural feature (TF) analysis was used to find a relationship between tumor type and TF values. Segmentation accuracy was evaluated quantitatively utilizing 70 clinical [¹⁸F]FDG-PET lung images of patients with a total of 150 solid tumors. For volumetric analysis, the Dice similarity coefficient (DSC) and Hausdorff distance (HD) measures were extracted with respect to gold-standard manual segmentation. A multi-linear regression model was also proposed for automated tumor labeling based on TFs, including cross-validation analysis.

Results

Two-tailed t test analysis of TFs between homogeneous and heterogeneous tumors revealed significant statistical difference for size-zone variability (SZV), intensity variability (IV), zone percentage (ZP), proposed parameters II and III, entropy and tumor volume (p < 0.001), dissimilarity, high intensity emphasis (HIE), and SUV_min (p < 0.01). Lower statistical differences were observed for proposed parameter I (p = 0.02), and no significant differences were observed for SUV_max and SUV_mean. Furthermore, the Spearman rank analysis between visual tumor labeling and TF analysis depicted a significant correlation for SZV, IV, entropy, parameters II and III, and tumor volume (0.68 ≤ ρ ≤ 0.84) and moderate correlation for ZP, HIE, homogeneity, dissimilarity, parameter I, and SUV_min (0.22 ≤ ρ ≤ 0.52), while no correlations were observed for SUV_max and SUV_mean (ρ < 0.08). The multi-linear regression model for automated tumor labeling process resulted in R ² and RMSE values of 0.93 and 0.14, respectively (p < 0.001), and generated tumor labeling sensitivity and specificity of 0.93 and 0.89. With respect to baseline random walk segmentation, the results showed significant (p < 0.001) mean DSC, HD, and SUV_mean error improvements of 21.4 ± 11.5 %, 1.4 ± 0.8 mm, and 16.8 ± 8.1 % in homogeneous tumors and 7.4 ± 4.4 %, 1.5 ± 0.6 mm, and 7.9 ± 2.7 % in heterogeneous lesions. In addition, significant (p < 0.001) mean DSC, HD, and SUV_mean error improvements were observed for tumor sub-volume delineations, namely 5 ± 2 %, 1.5 ± 0.6 mm, and 7 ± 3 % for the proposed Fuzzy RW method compared to RW segmentation.

Conclusion

We proposed and demonstrated an automatic framework for significantly improved segmentation and labeling of homogeneous vs. heterogeneous tumors in lung [¹⁸F]FDG-PET images.