Targeting Breast Cancer Using 177 Lu-Labeled Trastuzumab and Trastuzumab Fragment : First-in-Human Clinical Experience

PURPOSE

A monoclonal antibody, trastuzumab, is used for immunotherapy for HER2-expressing breast cancers. Large-sized antibodies demonstrate hepatobiliary clearance and slower pharmacokinetics. A trastuzumab fragment (Fab; 45 kDa) has been generated for theranostic use.

PATIENTS AND METHODS

Fab was generated by papain digestion. Trastuzumab and Fab have been radiolabelled with 177 Lu after being conjugated with a bifunctional chelating. The affinity and target specificity were studied in vitro. The first-in-human study was performed.

RESULTS

The bifunctional chelating agent conjugation of 1-2 molecules with trastuzumab and Fab was detected at the molar ratio 1:10 in bicarbonate buffer (0.5 M, pH 8) at 37°-40°C. However, 2-3 molecules of bifunctional chelating agent were conjugated when DMSO in PBS (0.1 M, pH 7) was used as a conjugation buffer at a molar ratio of 1:10. The radiolabelling yield of DOTA-conjugated Fab and trastuzumab at pH 5, 45°C to 50°C, with incubation time 2.5-3 hours was 80% and 41.67%, respectively. However, with DOTAGA-conjugated trastuzumab and Fab, the maximum radiolabelling yield at pH 5.5, 37°C, and at 2.5-3 hours was 80.83% and 83%, respectively. The calculated K d of DOTAGA Fab and trastuzumab with HER2-positive SKBR3 cells was 6.85 ± 0.24 × 10 -8 M and 1.71 ± 0.10 × 10 -8 M, respectively. DOTAGA-Fab and trastuzumab showed better radiolabelling yield at mild reaction conditions.177 Lu-DOTAGA-Fab demonstrated higher lesion uptake and lower liver retention as compared with 177 Lu-DOTAGA-trastuzumab. However, 177 Lu-DOTAGA-Fab as compared with 177 Lu-DOTAGA-trastuzumab showed a relatively early washout (5 days) from the lesion.

CONCLUSIONS

177 Lu-DOTAGA-Fab and trastuzumab are suitable for targeting the HER2 receptors.

Bio-evaluation of poly(lactic-co-glycolic) acid nanoparticles loaded with radiolabelled rifampicin

AIMS

The poly(lactic-co-glycolic) acid (PLGA) nanoparticles of tubercular drugs have been demonstrated to have a sustained release profile over 7 days. There is no information on the location or mode of release of these nanoparticles in living systems. Therefore, we have planned the study to explore the pharmacokinetics and biodistribution of PLGA rifampicin nanoparticles in healthy human volunteers. We aim to study the distribution pattern of PLGA-loaded nano-formulation of radiolabelled rifampicin in humans.

METHODS

Rifampicin was labelled with 99m Tc by indirect method and nanoparticles were prepared by a single emulsion evaporation method. To investigate the pharmacokinetics and biodistribution of nanoparticles, a single dose of 450 mg of rifampicin was administered orally to healthy human volunteers divided into two different groups.

RESULTS

Following a single oral dosage of the rifampicin nanoformulation, the pharmacokinetic (PK) parameters were significantly different between the nanoparticle and conventional groups: area under the concentration-time curve (AUC = 113.8 vs. 58.6; P < .001), mean residence time (MRT = 16.2 vs. 5.8; P < .01) and elimination rate constant (Ke  = 0.04 vs. 0.10; P < .05). Also, Single-photon emission computed tomography/computed tomography (SPECT/CT) images revealed biodistribution of nanoparticles in the distal portions of the intestine, which is consistent with our dosimetry analysis.

CONCLUSIONS

Significant difference in PK parameters and biodistribution of nanoparticles in spleen and lymph nodes with maximum deposition were observed in the large intestine. The nanoparticle distribution pattern may be advantageous for the treatment of intestinal or lymph node tuberculosis (TB) and has the potential to result in a lower dose of rifampicin nanoformulation for the treatment of pulmonary TB.

Improving outcomes for high-risk DLBCL: a pilot study looking at the role of fractionated cyclophosphamide with RCHOP chemo-immunotherapy (SCUBA-1 trial)

The outcomes for patients with high-risk DLBCL are suboptimal, especially in Low-middle income countries in comparison to published data from the western world. Most newer therapies aimed at improving outcomes are either unavailable or out of reach for the majority of patients in low-middle income countries. Cyclophosphamide is an easily available and accessible drug that forms the backbone for therapy for DLBCL. We conducted a single-center, open-label randomized pilot study comparing standard RCHOP to RCHOP with fractionated cyclophosphamide (RfCHOP) in patients with newly diagnosed, high-risk DLBCL. Fifty-five patients were randomized- 28 to RfCHOP and 27 to the RCHOP arm. RfCHOP was associated with a higher complete response rate than RCHOP at the end of 6 cycles of therapy (81.2% vs. 59.3%; p-0.062). Grade III/IV adverse events were comparable in both arms with the use of prophylactic GCSF in the RfCHOP arm. At a median follow-up of 22 months, the Median EFS and OS was not reached in either arm. RfCHOP may represent a therapeutic option for patients with newly-diagnosed, high-risk DLBCL, especially in Low-middle income countries. Larger studies are required to confirm these findings.

Abstract A10: Radiolabelled AMD3100 for the management of malignant lymphoma: Translational study

Introduction: Malignant lymphomas are heterogeneous group of neoplasm comprising of proliferating lymphoid cells or their precursors. The two main types of lymphoma are Hodgkin Lymphoma and Non- Hodgkin Lymphoma. The current treatment modalities include chemotherapy; radiation therapy; passive immunotherapy; radio-immunotherapy and small-molecule inhibitors. Radiation therapy is the treatment of choice if disease is localized. Targeted therapy with antibody and small molecules may be more suitable for malignant lymphomas. Lymphoma cells are reported to over-express chemokine receptors that favors leukocyte infiltration, promotes tumorigenesis, angiogenesis, immune evasion, and metastasis. Human CXCL4 and CCL5 oligomerize with over 20 chemokine subfamilies to control leukocytes infiltration. CXCR4 antagonists disrupt the specific interaction of chemokines with CXCR4 and may elicit therapeutic potential. Chemokine receptor 4 (CXCR4) has been explored with radiolabelled CXCR4 antagonist (AMD3100) for imaging and future targeted radiation therapy for malignant lymphoma. Methods: Standardization of conjugation of AMD3100 with bifunctional chelating agents (DTPA, NOTA etc.). Optimization include radiolabelling of conjugated AMD3100 with 68Ga and 177Lu for imaging and therapeutic purpose respectively. The radionuclide and radiochemical purity of the product was determined. CXCR4 binding efficacy and toxicity studies were performed on CXCR4 expressing cancer cell-lines. The quality control of radiolabelled AMD3100 included, radiochemical purity, sterility, pyrogenicity, human serum and PBS stability. The biodistribution studies were performed in normal rats. After obtaining clearance from institutional ethics committee,68Ga-AMD3100-DTPA PET/CT was performed in lymphoma patients (n=2). The uptake was compared with 18FDG uptake for proof of concept. Results: DTPA conjugation of AMD3100 (1087 Da) and NOTA conjugation (1014 Da) was confirmed with MALDI-TOF. The radionuclide and radiochemical purity of 68Ga and 177Lu AMD3100 was &gt;99%. Radio-ligand binding assay confirmed high specificity (Kd = 57.16 nM) of 177Lu-AMD3100-DTPA towards CXCR4 expressing cancer cells. Furthermore, the log absolute IC50 concentration of 177Lu-AMD3100-DTPA calculated for cytotoxicity assessment, via MTT assay, was 2.628 nM. Immunocytochemistry depicted positive nuclear staining of CXCR4 receptors in cancer cells. The synthesized radiopharmaceuticals were sterile and pyrogen-free. In-vivo physiological biodistribution of 68Ga-AMD3100-DTPA was found in liver, lung and spleen. The radiotracer showed faster renal clearance and low blood pool activity. In addition to physiological uptake, 68Ga-AMD3100-DTPA PET/CT showed similar lesions that were seen in 18FDG PET/CT of lymphoma patients. Conclusion: 68Ga/177Lu-AMD3100-DTPA demonstrated high target specificity towards CXCR4 expressing lymphoma cells. Cytotoxicity and patient study indicated its potential as theranostic agent. It can be used for the selection of patients, targeted therapy and response evaluation.

Citation Format: Tamanna Lakhanpal, Jaya Shukla, Rajender Kumar, Harmanpreet Singh, Pankaj Malhotra, Alka Khadwal, Gaurav Prakash, Amanjit Bal, Yogesh Rathore, BR Mittal. Radiolabelled AMD3100 for the management of malignant lymphoma: Translational study [abstract]. In: Proceedings of the Third AACR International Meeting: Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2022 Jun 23-26; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2022;3(5_Suppl):Abstract nr A10.

Molecular Imaging Targeting Corticotropin-releasing Hormone Receptor for Corticotropinoma: A Changing Paradigm

BACKGROUND

Corticotrophin-releasing hormone (CRH) is the major regulator of adrenocorticotrophic hormone (ACTH) secretion from the anterior pituitary and acts via CRH-1 receptors (CRH-1R). Corticotropinoma though autonomous, still retain their responsiveness to CRH and hence, we hypothesize that in vivo detection of CRH-1 receptors on pituitary adenoma using Gallium-68 (68Ga)-tagged CRH can indicate the functionality of adenoma, and combining it with positron emission tomography-computed tomography (PET-CT) can provide requisite anatomical information.

METHODS

Subjects with ACTH-dependent Cushing's syndrome (CS) (n = 27, 24 with Cushing's disease [CD], 3 with ectopic CS [ECS]) underwent 68Ga CRH PET-CT. Two nuclear medicine physicians read these images for adenoma delineation and superimposed them on magnetic resonance imaging (MRI) sella. The information provided was used for intraoperative navigation and compared with operative and histopathological findings.

FINDINGS

68Ga CRH PET-CT correctly delineated corticotropinoma in all the 24 cases of CD, including the 10 cases with adenoma size < 6mm (4 cases were negative on MRI). Corticotropinoma location on 68Ga CRH PET fusion images with MRI were concordant with operative findings and were further confirmed on histopathology. There was no tracer uptake in the pituitary in 2 patients with ECS, while, in another, the diffuse uptake in pituitary suggested ectopic CRH production.

CONCLUSION

68Ga CRH PET-CT represents a novel, noninvasive molecular imaging, targeting CRH receptors that not only delineate corticotropinoma and provides the surgeon with valuable information for intraoperative tumor navigation, but also helps in differentiating a pituitary from an extra-pituitary source of ACTH-dependent CS.

FUNDING

None.

Efficacy of Bacopa Monnieri (Brahmi) and Donepezil in Alzheimer's Disease and Mild Cognitive Impairment: A Randomized Double-Blind Parallel Phase 2b Study

Objectives:

Alzheimer's disease (AD) is the most common cause of dementia worldwide in the older population. There is no disease-modifying therapy available for AD. The current standard of care drug therapy for AD is cholinesterase inhibitors, including donepezil. Bacopa monnieri or brahmi is used in traditional Indian medicine for memory loss. We conducted a phase 2b randomized controlled trial (RCT) to find out the efficacy of brahmi and donepezil in AD and mild cognitive impairment (MCI).

Patients and Methods:

The study was planned as a 52 week, randomized, double-blind, parallel-group, phase-2 single-center clinical trial comparing the efficacy and safety of Bacopa monnieri (brahmi) 300 mg OD and donepezil 10 mg OD for 12 months in 48 patients with AD and MCI-AD including cognitive and quality of life outcomes. The primary outcome was differences in the change from baseline of the neuropsychological tests [Alzheimer's disease assessment scale-cognitive subscale (ADAS-Cog) and postgraduate institute (PGI) memory scale] at 12 months between the intervention group (brahmi) and active comparison group (donepezil).

Results:

The study was terminated after 3 years and 9 months, after recruiting 34 patients, because of slow recruitment and a high dropout rate. Intention to treat analysis after adjusting for baseline confounders showed no difference in the rate of change in ADAS-Cog score from baseline at any time point, including the last follow-up. There was no difference in the rate of change in PGI Memory scale (PGIMS) at 3, 6, and 9 months. In the last follow-up, there was a significant difference in the change in total PGIMS score between brahmi and donepezil, while there was no difference in individual scores of the PGI memory scale.

Conclusion:

This phase-2 RCT on the efficacy of brahmi vs. donepezil showed no significant difference between them after 1 year of treatment. Larger phase-3 trials, preferably multicentric, are required to find the superiority of brahmi over donepezil.

Prospective observational study evaluating acute and delayed treatment related toxicities of prophylactic extended field volumetric modulated arc therapy with concurrent cisplatin in cervical cancer patients with pelvic lymph node metastasis

PURPOSE

To evaluate the treatment related acute and delayed toxicities of extended field Volumetric modulated arc therapy (VMAT) with concurrent chemotherapy in patients of locally advanced cervical cancer with pelvic lymph nodes.

MATERIAL AND METHODS

From 2014 to 2016, 15 patients of locally advanced cervical cancer with Fluoro-deoxyglucose positron emission tomography (FDG-PET) positive pelvic lymph nodes were treated with extended field Simultaneous integrated boost (SIB)-VMAT 45 Gy/55 Gy/25#/5weeks and concurrent cisplatin. Acute toxicities were documented according to common terminology criteria for adverse events version 4 (CTCAE v.4). Dose volume parameters and patient characteristics were analyzed for association with toxicities.

RESULTS

Median age of patients at diagnosis was 48 years. 40% (6 patients) were stage IIB & 60% (9 patients) were stage IIIB. Median number of involved pelvic lymph nodes was 2 (range, 1-4), commonest location was external iliac lymph node region (86%). Median number of concurrent chemotherapy cycles received was five. Treatment was well tolerated and there were no grade ≥ 3 acute toxicities. Commonest acute toxicities observed were vomiting (≥grade2 -13.3%) followed by & nausea (grade ≥ 2 in 6%) and were associated with volume of bowel bag receiving 45 Gy. Constitutional symptoms (≥grade 2) were observed in 6% patients and had no dosimetric associations. At a median follow up of 43 months, delayed ≥ grade1, 2, 3 toxicity were observed in 80%, 0%, and 0% respectively with diarrhea being the commonest.

CONCLUSION

Prophylactic para aortic extended field VMAT with concurrent chemotherapy for locally advanced cervical cancer is well tolerated with acceptable acute toxicity profile. Significant grade 3 acute/delayed toxicities were not observed in this cohort of patients.

Formulation of ‘ready-to-use’ human clinical doses of 177Lu-labeled bisphosphonate amide of DOTA using moderate specific activity 177Lu and its preliminary evaluation in human patient

Radiolabeled macrocyclic bisphosphonate ligands have recently been demonstrated to be highly efficacious in treatment of patients with painful bone metastases. Herein, we report a robust protocol for formulation of therapeutically relevant doses of 177Lu-labeled bisphosphonate amide of DOTA (BPAMD) using moderate specific activity 177Lu produced by direct (n,γ) route and its preliminary investigation in human patients. Doses (2.8 ± 0.2 GBq) were formulated with high radiochemical purity (98.3 ± 0.4 %) using a protocol optimized after extensive radiochemical studies. In vitro binding studies with mineralized osteosarcoma cells demonstrated specific binding of the radiotracer. Biodistribution studies in healthy Wistar rats demonstrated rapid skeletal accumulation with fast clearance from the non-target organs. In a patient administered with 555 MBq dose of 177Lu-BPAMD, intense radiotracer uptake was observed in the metastatic skeletal lesions with insignificant uptake in any other major non-targeted organs. Preliminary clinical investigations carried out after administration of 2.6 GBq of 177Lu-BPAMD revealed significant reduction in pain after 1 week without any adverse effects. The developed protocol for formulation of 177Lu-BPAMD doses using moderate specific activity carrier added 177Lu has been found to be effective and warrants wider investigations in patients with painful skeletal metastases.

THU0531 A PROSPECTIVE STUDY EVALUATING THE ROLE OF 68GA-RGD2 PET/CT ANGIOGENESIS IMAGING IN ASSESSING DISEASE ACTIVITY AND TREATMENT RESPONSE IN RHEUMATOID ARTHRITIS AND ITS COMPARISON WITH DAS28

Background:

PET/CT imaging of synovial angiogenesis using68Ga-RGD (cyclic tripeptide agent targeting αvβ3integrin) to study disease activity in rheumatoid arthritis (RA) has been demonstrated earlier in a few patients. However, post treatment changes in disease activity on68Ga-RGD2PET/CT imaging have not been adequately assessed.

Objectives:

To compare the performance of68Ga-RGD2PET/CT with disease activity score (DAS) 28 in assessing disease activity and treatment response in RA.

Methods:

Thirty patients (24F, 6M) aged 43±12 years with clinically diagnosed RA were prospectively studied. After calculation of DAS28 by a rheumatologist, all 30 patients underwent68Ga-RGD2PET/CT scan. Of these, 27 patients underwent a second68Ga-RGD2PET/CT scan and clinical assessment after at least 3 months of treatment. Total body and regional images of the upper limbs were acquired and interpreted by two nuclear medicine physicians blinded to the clinical findings. Joints showing focally increased tracer uptake compared to the background were considered positive and joints showing uptake equal to or less than background were considered negative. Data of 30 patients were used for inter-observer and inter-modality agreement calculations. Changes in PET parameters and DAS28 were compared in 27 patients to assess treatment response.

Results:

Out of 1560 joints examined in the initial scan, 394 were positive on PET/CT compared to 348 on clinical evaluation. Inter-observer agreement between nuclear medicine physicians was excellent (Cohen’s kappa 0.92, p<0.05) and inter-modality agreement between PET and clinical examination was moderate (Cohen’s kappa 0.55, p<0.05). The DAS28 and SUVmax values (highest and average) of 27 patients showed significant reduction on follow-up compared to the initial evaluation. There was significant correlation between percentage change in DAS28 and percentage change in scan parameters like PET positive joint counts (0.689, p<0.001), average SUVmax (0.712, p<0.001) and highest SUVmax values (0.558, p=0.003) of scan-positive joints in 27 patients. Additional advantages of68Ga-RGD2PET/CT included objective assessment, whole body evaluation of all small and large joints, and greater reproducibility.

Conclusion:

68Ga-RGD2PET/CT is a promising tool for objective assessment of disease activity and treatment response in patients with RA.

Table 1.

Clinical and PET parameters of the patients

ParameterInitial data (n=27)Mean (SD)/Median (IQR)Follow-up data (n=27)Mean (SD)/Median (IQR)TJC(28)10 (5-13)3 (2-4)SJC(28)6 (3-7)1 (0-2)ESR25 (20-41)24 (18-35)PtGA6.0 (5.0-6.0)3.0 (2.0-4.0)DAS28(3)5.14 (0.85)3.74 (0.88)DAS28(4)5.60 (0.90)3.80 (0.96)PET positive Joints12 (7-8)4 (2-9)aSUVmax2.08 (1.68-2.52)1.79 (1.00-2.06)hSUVmax3.45 (2.71-4.70)3.34 (1.95-4.25)

TJC/SJC: tender/swollen joint counts; ESR: erythrocyte sedimentation rate; PtGA: patients global assessment scale; DAS: disease activity score; aSUVmax/hSUVmax: average/highest SUVmax (maximum standardized uptake value); SD: standard deviation; IQR: interquartile range

Figure 1.

68Ga-RGD2PET scan of a 26-year female RA patient on treatment.A.Initial scan shows increased tracer uptake in multiple joints of upper and lower limbs and tendon sheaths of hands and ankle region (arrows); DAS28 was 4.56 (moderate disease activity) and ESR 12 mm/1sthour.B. Follow-up scan after 4 months shows resolution of tracer activity in the previously involved joints with only a mild focus persisting in the left knee joint; DAS28 was 1.73 (clinical remission according to ARA) and ESR 08 mm/1sthour.

Acknowledgments:

This study was supported by Indian Council of Medical Research, New Delhi [grant no.3/2/June-2017/PG-Thesis-HRD (23)]

Disclosure of Interests:

None declared

Radio-pathological Correlation of 18F-FDG PET in Characterizing Gallbladder Wall Thickening

AIM

Thick-walled gallbladder is difficult to characterize on conventional imaging. 18F-FDG PET was used to differentiate benign and malignant wall thickness and compared with histopathology.

METHODS

Thirty patients with gallbladder (GB) wall thickening (focal > 4 mm and diffuse > 7 mm), underwents uspected on  ultrasound, or CT scan, and underwent 18F-FDG PET. Histopathology of the specimen was compared with imaging findings.

RESULTS

The mean age was 48.22 ± 31.33 years with a M:F 1:4 ratio. Twenty patients had diffuse and 10 had focal thickening. On 18F-FDG PET, lesion was benign in 12, malignant in 13, and indeterminate in 5. Histopathology was malignancy in 12; benign in 18-chronic cholecystitis in 11, xanthogranulomatous in 4, IgG4 related in 2, and polyp in 1. The mean GB wall thickness was 7.79 ± 3.59 mm (10.34 malignant and 6.10 in benign, p = 0.001). At a cutoff of 8.5 mm, the sensitivity and specificity of detecting malignancy was 94% and 67%. The mean SUV uptake was 7.46 (benign 4.51, malignant 14.26, p = 0.0102). At a cutoff of 5.95, the sensitivity and specificity of detecting malignancy was 92% and 79%. For 18F-FDG PET, overall sensitivity was 91%, specificity 79%, PPV 77%, NPV 92%, and diagnostic accuracy was 84%.

CONCLUSION

18F-FDG PET is a reliable method of differentiation between benign and malignant thickening of the gallbladder particularly when wall thickness and SUV value is taken into account.

Positron emission tomography/computed tomography guided percutaneous biopsies of Ga-68 avid lesions using an automated robotic arm

PURPOSE

The purpose of this prospective study was to evaluate the feasibility of positron emission tomography/computed tomography (PET/CT)-guided biopsy of Ga-68 avid lesions using an automated robotic arm and determine the diagnostic yield of this technique.

MATERIAL AND METHODS

Patients who underwent Ga-68 labelled tracers imaging followed by PET/CT-guided biopsies of tracer-avid lesions were prospectively included. Biopsies were performed using a dedicated automated-robotic-arm assisted PET/CT-guided biopsy device on the same-day of diagnostic PET/CT-imaging. The tissue samples were retrieved after confirming the position of needle-tip in the target lesion. Procedure-related complications and radiation exposure of the interventionist were recorded. Histopathological reports were reviewed for diagnostic yield.

RESULTS

A total of 25 patients (19 men, six women) with a mean age of 50.8±17.3 (SD) years (range: 17-83 years) were included. The biopsies were performed after PET/CT using Ga-68 DOTANOC (n=16) or Ga-68 PSMA (n=8) and Ga-68 chemokine-analogue (n=1). The biopsy samples were obtained from the liver (n=9), bone (n=8), lymph-nodes (n=3), lung (n=1), pancreas (n=1), anterior mediastinal lesion (n=1), peritoneal-deposit (n=1) and thigh-lesion (n=1). No immediate or delayed procedure-related complications were documented in any patient. PET/CT-guided molecular sampling was technically successful in all the patients. Histopathology revealed malignancies in all the biopsied specimens without the need for repeat sampling or further invasive-diagnostic workup, with a diagnostic yield of 100%. The estimated absorbed-radiation dose was 566.7μSv/year for the interventionist.

CONCLUSION

PET/CT-guided molecular biopsy using Ga-68 labelled radiotracers is feasible and can be performed safely and accurately with a high-diagnostic yield. It is helpful in accurately staging the disease when tracer-avid isolated distant lesion evident on imaging and highly practical in patients with previous inconclusive sampling.

68Ga-Glutathione radio-complex as a new diagnostic probe for targeting colon cancer in rats

OBJECTIVE

Glutathione (GSH) plays an important role in a horde of cellular events that include cell proliferation and apoptosis.The present study describes the radio-synthesis and characterization of gallium-68 (⁶⁸Ga)-labelled glutathione for its application in radionuclide imaging of cancer.

SUBJECT AND METHODS

The radio-synthesis of radio-complex ⁶⁸Ga-GSH was performed by the direct labeling method. The developed radio-complex was subjected to quality control tests. Colon tumors were developed in healthy male Sprague Dawley (S.D) rats by giving subcutaneous injections of dimethylhydrazine (DMH) in order to monitor the uptake of ⁶⁸Ga-GSH radio-complex.

RESULTS

Gallium-68-labelled glutathione was synthesized with a labeling efficiency of 73.5%±1%. Percentage plasma protein binding and log Po/w values for the radio-complex were found to be 20%-30% and -0.223±0.12, respectively. A significantly higher percentage specific uptake value of newly developed ⁶⁸Ga-GSH complex was observed in colon tumor in comparison to soft tissue at 90 minutes post administration thereby exhibiting specificity for cancerous cells, which was also witnessed significantly increased overtime from the ratio of colon tumor uptake to normal colon uptake (P≤0.05).

CONCLUSION

Therefore, ⁶⁸Ga-labelled glutathione can further be exploited for radionuclide imaging and assessment of tumor drug resistance in patients.

Endoscopic Management of Vesicoureteral Reflux and Long-term Follow-up

OBJECTIVE

To report our experience with endoscopic management of vesicoureteral reflux (VUR) by injection of a tissue bulking substance - Dextranomer/ hyaluronic acid co-polymer at vesicoureteric junction.

DESIGN

Retrospective analyses of case records.

SETTING

Pediatric Surgery department in a tertiary care government Institute.

PARTICIPANTS

500 children (767 renal units) consecutively referred to the out-patient department with vesicoureteral reflux noted on micturating cysto-urethrogram (MCU) over a period of 13 years (2004-2016).

INTERVENTION

Preoperative VUR grading and renal scars on radionuclide scans were documented. Dextranomer hyaluronic acid copolymer was injected through a cystoscope at the vesicoureteral junction as a day care procedure under short anesthesia. Patients were followed (average duration 27.3 mo) with clinical assessment, periodic urine cultures and renal scans.

MAIN OUTCOME MEASURE

Cessation of VUR and symptomatic relief / clinical success postoperatively at 3 months.

RESULTS

Complete symptomatic relief was obtained in 482 (96.4%) patients. In 681 units where MCU was available, 614 (90%) units showed resolution of VUR.

CONCLUSIONS

Endoscopic injection of tissue bulking substances at vesicoureteric junction to stop VUR seems to be an effective intervention.

Infiltrative Optic Neuropathies: Opening Doors to Sinister Pathologies

Optic disc edema may be caused by a number of conditions. A commonly ignored but important aspect is the presence of "infiltration" of disc; that may closely mimic disc edema. Disc edema, optic nerve dysfunction and a normal appearing disc in any combination may occur in infiltrative optic neuropathies. Identifying disc infiltration can aid in diagnosis of many sinister pathologies even in the absence of other specific clinical features. We describe two patients presenting with optic nerve dysfunction and infiltrated disc appearance, which on investigations were found to have underlying malignancies thereby underscoring the importance of detecting infiltrative optic neurpathies.

Role of inflammatory and hemostatic biomarkers in Alzheimer's and vascular dementia - A pilot study from a tertiary center in Northern India

INTRODUCTION

A reliable plasma biomarker in differentiating between Alzheimer's disease (AD) and Vascular dementia (VaD) is the need of the hour, in most memory clinics. Even though there is no disease modifying treatment, it is important to know the type of dementia for both symptomatic treatment and prognostication.

METHODS

Neuropsychological assessment, MRI brain, FDG-PET brain and CSF biomarkers of AD (Aβ42 and total tau) were used for establishing the diagnosis of Mild Cognitive Impairment (MCI), AD or VaD.

RESULTS

68 diagnosed patients of AD/MCI/VaD were included. FDG PET brain, plasma fibrinogen, d dimer, IL6 and CRP were done in all 68 patients while 48 patients underwent CSF biomarker analysis. Sixteen patients had MCI, of which 11 were MCI-AD and 5 were MCI-VaSC. There were 41 patients with AD (Mild AD-9, Mod AD-23, Severe AD-9) and 11 patients with VaD. Alzheimer group (MCI-AD and AD) and Vascular group (MCI VaSC & VaD) consisted of 52 and 16 patients respectively. Alzheimer and Vascular groups did not exhibit significant difference in IL6 and CRP levels. Plasma fibrinogen levels were significantly higher in VaD and vascular group as compared to Alzheimer group. But MCI-VaSC was not significantly different from MCI-AD. Plasma d dimer levels were significantly higher in all vascular subgroups compared to Alzheimer subgroups except between MCI-VaSC and MCI-AD.

CONCLUSION

Hemostatic biomarkers were higher in Vascular group compared to Alzheimer group whereas there was no difference in inflammatory biomarkers. But the sensitivity and specificity of fibrinogen and d-dimer were not high enough for routine clinical use. Further studies in a larger sample are required to confirm these results.

Evaluation of MR perfusion abnormalities in organophosphorus poisoning and its correlation with SPECT

AIM

Acute organophosphate (OP) pesticide poisoning causes substantial morbidity and mortality worldwide. Many imaging modalities, such as computerized tomography (CT), magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT) of the brain, have been used for quantitative assessment of the acute brain insult caused by acute OP poisoning. Perfusion defects on SPECT in acutely poisoned patients with OPs have been described, however, MR perfusion abnormalities have not been described in the literature. MR perfusion Imaging has the advantage of having higher spatial resolution, no radiation, and better availability.

MATERIALS AND METHODS

In this prospective study, 20 patients who ingested OP compounds were included. All the patients underwent brain SPECT on a dual head SPECT gamma camera and MRI brain on a 1.5T MR system. Neurocognitive tests were performed for all patients.

RESULTS

SPECT showed perfusion defects in 7 patients and total number of perfusion defects were 29. On MR perfusion, based on the cut-off values of normalized cerebral blood volume (nCBV) ratios and normalized cerebral blood flow (nCBF) ratios, the total number of patients showing perfusion defects were 6 and 8; and the total number of perfusion defects were 29 and 45, respectively. There was significant difference of the nCBV ratios and nCBF ratios between the control group (n = 20) and positive patients group (n = 6 and n = 8, respectively) (P > 0.05). All the defects seen on SPECT were well appreciated on nCBF maps (MRI perfusion) suggestive of 100% correlation.

CONCLUSION

MR perfusion imaging can be used as an effective modality for evaluation in acute OP poisoning.

Effect of curative parathyroidectomy on insulin resistance

BACKGROUND

Primary hyperparathyroidism (PHPT) is characterized by inappropriately elevated serum parathyroid hormone (PTH) level despite elevated serum calcium. Insulin resistant is the basic pathophysiology, behind the higher prevalence of diabetes mellitus in patients with PHPT. However, the improvement in insulin resistance (IR) after curative parathyroidectomy (CPTX) has not been established yet, as the study results are conflicting.

MATERIALS AND METHODS

In this prospective interventional study, ten patients with mild PHPT (Group 1) and another ten patients with moderate to severe PHPT (Group 2) were undergone CPTX. The IR was assessed by homeostasis model assessment-IR (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), fasting plasma glucose (FPG), and fasting serum insulin (FSI), before and 3 months after CPTX.

RESULTS

There was no significant change of FPG and FSI, before and after CPTX in Group 1 (P = 0.179 and P = 0.104) and Group 2 (P = 0.376 and P = 0.488). Before surgery, HOMA-IR was higher, and QUICKI was significantly lower, in both Group 1 (P = 0.058 and P = 0.009) and Group 2 (P = 0.023 and P = 0.005) as compared to published normal reference mean, with no significant difference between the groups. Three months after surgery HOMA-IR increased further and QUICKI remained unchanged as compared to baseline, in both Group 1 (P = 0.072 and 0.082) and Group 2 (P = 0.54 and 0.56), but statistically insignificant.

CONCLUSION

IR remained unchanged after CPTX in mild as well as moderate to severe PHPT. Asymptomatic PHPT with abnormal IR should not be used as criteria for parathyroidectomy.

Detailed evaluation of different (68)Ge/(68)Ga generators: an attempt toward achieving efficient (68)Ga radiopharmacy

The present study is aimed at carrying out a comparative performance evaluation of different types of (68)Ge/(68)Ga generators to identify the best choice for use in (68)Ga-radiopharmacy. Over the 1 year period of evaluation, the elution yields from the CeO2-based and SiO2-based (68)Ge/(68) Ga generators remained almost consistent, in contrast to the sharp decrease observed in the elution yields from TiO2 and SnO2-based generators. The level of (68)Ge impurity in (68)Ga eluates from the CeO2 and SiO2-based (68)Ge/(68)Ga generator was always <10(-3)%, while this level increased from 10(-3)% to 10(-1)% in case of TiO2 and SnO2-based generators. The level of chemical impurities in (68)Ga eluates from CeO2 and SiO2-based (68)Ge/(68)Ga generators was negligibly low (<0.1 ppm) in contrast to the significantly higher level (1-20 ppm) of such impurities in eluates from other two generators. As demonstrated by radiolabeling studies carried out using DOTA-coupled dimeric cyclic RGD peptide derivative (DOTA-RGD2), CeO2-PAN and SiO2-based generators are directly amenable for radiopharmaceutical preparation, whereas the other generators can be only used after post-elution purification of (68)Ga eluates. Clinically relevant dose of (68)Ga-DOTA-RGD2 was prepared in a hospital radiopharmacy for non-invasive visualization of tumors in breast cancer patients using positron emission tomography.

Toward realization of 'mix-and-use' approach in ⁶⁸Ga radiopharmacy: preparation, evaluation and preliminary clinical utilization of ⁶⁸Ga-labeled NODAGA-coupled RGD peptide derivative

INTRODUCTION

The present article demonstrates a 'mix-and-use' approach for radiolabeling RGD peptide derivative with (68)Ga, which is easily adaptable in hospital radiopharmacy practice. The radiotracer thus formulated was successfully used for positron emission tomography (PET) imaging of breast cancer in human patients.

METHODS

The conditions for radiolabeling NODAGA-coupled dimeric cyclic RGD peptide derivative [NODAGA-(RGD)2] with (68)Ga were optimized using (68)Ga obtained from a (68)Ge/(68)Ga generator developed in-house with CeO2-PAN composite sorbent as well as from a commercial (68)Ge/(68)Ga generator obtained from ITG, Germany. Preclinical studies were carried out in C57BL/6 mice bearing melanoma tumors. The radiotracer was prepared in a hospital radiopharmacy using (68)Ga obtained from ITG generator and used for monitoring breast cancer patients by positron emission tomography (PET) imaging.

RESULTS

(68)Ga-NODAGA-(RGD)2 could be prepared with high radiolabeling yield (>98%) and specific activity (~50 GBq/μmol) within 10 min at room temperature by mixing (68)Ga with the solution of the peptide conjugate. In vivo biodistribution studies showed significant uptake (5.24±0.39% ID/g) in melanoma tumor at 30 min post-injection, with high tumor-to-background contrast. The integrin αvβ3 specificity of the tracer was corroborated by blocking study. Preliminary clinical studies in locally advanced breast cancer (LABC) patients indicated specifically high tumor uptake (SUVmax 10-15) with good contrast.

CONCLUSIONS

This is one of the very few reports which presents preliminary clinical data on use of (68)Ga-NODAGA-(RGD)2 and the developed 'mix-and-use' holds tremendous prospect in clinical PET imaging using (68)Ga.

Follow-up (99m)Tc EC renal dynamic scintigraphy and DMSA-III SPECT/CT in unmasking a masqueraded case of Horseshoe kidney

Hydronephrosis is a common finding in urinary tract outflow obstruction. Chronically obstructed hydronephrotic system may be associated with parenchymal changes. Ultrasound, intravenous urography, micturating cysto-urethrogram and scintigraphy are commonly performed to evaluate the cause of obstruction. In childhood, pelviureteric junction obstruction is a common cause of the hydronephrosis. Hydronephrosis can also be present in horseshoe kidneys due to poor drainage. However, a large sized hydronephrotic cavity may obscure the finding of horseshoe kidney. A case was reported, and it was diagnosed as horseshoe kidney on follow-up renal dynamic scan and confirmed with the help of dimercaptosuccinic acid SPECT/CT.

Pyrexia, Lung nodules, Granulomas: Pulmonary Lymphomatoid Granulomatosis

The differential diagnosis of pyrexia, lung nodules and granulomas includes tuberculosis, vasculitis and rarely a malignancy. In countries where tuberculosis or histoplasmosis is endemic, these are the first consideration and often ruled out by microbiological investigations. Vasculitis like granulomatosis with polyangitis (Wegener's granulomatosis), Churg strauss syndrome and sarcoidosis, which are the second consideration, are ruled out by serological investigations. Confirmation of malignancy merits histopathology. This case highlights how a rare diagnosis of pulmonary lymphomatoid granulomatosis was reached after an open lung biopsy. The following case also describes the natural history of this rare disease as it showed transient spontaneous remission but ultimately required therapy.

A late recurrence of renal cell carcinoma as pancreatic metastases: a rare disease

A man presented with multifocal pancreatic metastases 9 years after nephrectomy for renal cell carcinoma. He was managed with oral sunitinib. He had favourable response to treatment with excellent compliance.

Comparison of nitrate augmented Tc-99m tetrofosmin gated SPECT imaging with FDG PET imaging for the assessment of myocardial viability in patients with severe left ventricular dysfunction

BACKGROUND

Of various nuclear medicine techniques, F-18/flourodeoxyglucose (FDG) positron emission tomography (PET) is considered as the best modality for the assessment of viable myocardium (VM). In this study, we compared the diagnostic accuracy of nitrate augmented Tc-99m tetrofosmin gated G-single-photon emission computed tomography (SPECT) with FDG PET.

METHODS

54 consecutive cases of angiographically proven CAD with severe LV dysfunction were enrolled in the study. The patients underwent Tc-99m tetrofosmin G-SPECT and FDG PET as per the standard protocols and were compared.

RESULTS

SPECT data analysis indicated functional abnormalities in 661/918 myocardial segments. F-18 FDG PET revealed VM in 496/661 segments. The diagnostic accuracy of baseline NAC, postnitrate NAC, baseline AC, and postnitrate AC Tc-99m tetrofosmin SPECT was 84%, 87%, 90%, and 94%, respectively. κ values for NAC baseline, NAC postnitrate, AC baseline, and AC postnitrate Tc-99m tetrofosmin G-SPECT were 0.65, 0.70, 0.77, and 0.85, respectively. Attenuation correction revealed viability additionally in 46 segments which were non-viable on NAC postnitrate study (P < .001). Nitrate augmentation showed viability additionally in 25 segments which were non-viable on AC baseline scan (P = .004). On patient-based analysis FDG PET changes the management only in 13% (7/54) of patients.

CONCLUSIONS

Nitrate augmented AC Tc-99m tetrofosmin G-SPECT shows excellent (κ = .85) agreement with FDG PET. FDG PET changes management only in 13% of the patients. Tc-99m tetrofosmin G-SPECT being more widely available and cheaper imaging modality can be reliably used to detect VM where FDG PET is not available.

Influence of age and gender on presentation of symptomatic primary hyperparathyroidism

BACKGROUND

The geographical difference in presentation of primary hyperparathyroidism (PHPT) is known. However, there is sparse literature on the influence of age and gender on presentation of PHPT.

AIM

To analyze the effect of age and gender on presentation of symptomatic primary hyperparathyroidism.

SETTING AND DESIGN

This is a retrospective analysis of data from the primary hyperparathyroidism registry of a north Indian tertiary care teaching institute.

MATERIALS AND METHODS

Analysis of 184 histopathologically proven PHPT patients registered between March 1990 and March 2010 from a single centre of north India. PHPT patients were divided into three different age groups i.e. children and adolescents less than 25 years, adults 25-49 years, and ≥ 50 years. Clinical presentations, biochemical parameters and parathyroid weight were compared between different age groups and gender using appropriate statistical methods.

RESULTS

Mean age of patients was 38.5±13.8 years with female: male ratio of 7:3. Rickets as presenting manifestations were seen in one child and adolescent each. Prevalence of renal stones (P=0.03) and gall stones (P=0.02) was higher in the adult groups compared to the younger and older. There was no difference in bone pain (P=0.7), fracture (P=0.3), osteitis fibrosa cystica (P=0.2), fatigue (P=0.6) and other symptoms among different age groups. There was no difference in serum calcium, phosphate, parathyroid hormone (PTH) and 25 (OH) D levels among different age groups, however, as expected alkaline phosphatase was higher in adolescents compared to adults (P=0.03). Bone pain and muscle aches (P<0.001), fracture (P=0.04), osteitis fibrosa cystica (P=0.01), and gall stones (P=0.03) were more common among women while renal stones (P=0.05) and pancreatitis (P=0.02) were common in men. Serum calcium and phosphate levels were similar in either sex but parathyroid hormone (iPTH) level was higher among women (P=0.02). Parathyroid adenoma weight was higher in older compared to young but did not reach to a level of statistical significance.

CONCLUSION

Age and gender have substantial influence on presentation of PHPT. Bone pain and rickets were common in children and adolescents while renal stones in adults. Women have more severe disease as musculoskeletal manifestations are common and iPTH levels are also higher compared to men.

(18)F-FDG Positron Emission Tomography in Multifocal Pyomyositis

¹⁸F-Fluoro-deoxyglucose–positron emission tomography/computed tomography findings in a case presenting with pyomyositis are presented in this report.

Reversible delayed neuropsychiatric syndrome following acute carbon monoxide exposure

A 40-year-old male presented with acutely oncoming neuropsychiatric symptoms in the form of extrapyramidal disturbances, personality change, behavior changes and urinary incontinence. One month prior to this symptomatology, he had been found unconscious in his closed room where a coal fire was burning overnight. He recovered completely in two days with supportive therapy. Magnetic resonance imaging during this presentation showed bilateral white matter changes suggestive of demyelination. Tc99m-ECD SPECT study revealed hypoperfusion in bilateral frontal region. He was managed conservatively and eventually made a nearly complete recovery. Repeat SPECT study revealed marked improvement in tracer uptake correlating with his improvement. Delayed neuropsychiatric syndrome after acute carbonmonoxide poisoning is a rare and distinct entity. This case report discusses the various aspects of this disease entity.

Posterior urethral valves: Morphological normalization of posterior urethra after fulguration is a significant factor in prognosis

AIM

To assess the changes in urethral morphology 3 months post fulguration of posterior urethral valves (PUVs) on micturating cystourethrogram (MCUG) and correlate these changes with the overall clinical status of the patient.

MATERIALS AND METHODS

A total of 217 children, managed for PUVs during a period of 6 years in a single surgical unit were prospectively studied. The ratio of the diameters of the prostatic and bulbar urethras (PU/BU) was calculated on the pre- and post-fulguration MCUG films. They were categorized into three groups based on the degree of normalization of posterior urethra (post-fulguration PU/BU ratio).

RESULTS

GROUP A

Of the 133 patients, 131 had normal urinary stream and 4 (3%) had nocturnal enuresis. Vesicoureteral reflux (VUR), initially seen in 83 units (31% units), regressed completely at a mean duration of 6 months in 41 units (49%). Of the 152 non-VUR, hydroureteronephrosis (HUN) units, 11 were poorly functioning kidneys. Persistent slow but unobstructed drainage was seen in 23 units (16%) over a period of 1.5-5 years (mean 2.5 years). Group B: All the 11 patients had a normal stream. Four (36.4%) had daytime frequency for a mean duration of 1 year and one (9%) had nocturnal enuresis for 1 year. Grade IV-V VUR was seen in five patients (three bilateral), which regressed completely by 3 months in five units (62.5%). In the non-VUR, HUN patients, slow (but unobstructed) drainage was persistent in two units (14%) at 3 years. Group C: Of the 16 patients, only 5 (31.3%) were asymptomatic. Six patients (nine units) had persistent VUR for 6 months to 3 years. Of the 20 units with HUN, 17 (85%) were persistent at 1-4 years (mean 2 years). Eight patients (50%) required a second fulguration while 3 (18.7%) required urethral dilatation for stricture following which all parameters improved.

CONCLUSIONS

Adequacy of fulguration should be assessed by a properly performed MCUG. A postop PU/BU ratio >3 SD (1.92) should alert to an incomplete fulguration or stricture. Patients within normal range ratio have faster recovery of slow draining units, reflux and less voiding dysfunction. There is a strong correlation between incomplete fulguration and persistent slow draining units, uremia, voiding dysfunction and urinary tract infections.

Computed tomographic pulmonary angiography: utility in acute pulmonary embolism in providing additional information and making alternative clinical diagnosis

OBJECTIVE

To evaluate the role of computed tomographic (CT) pulmonary angiography (CT-PA) in detecting additional information that may help in making an alternative clinical diagnosis in patients referred to CT for a suspected acute pulmonary embolism (PE).

MATERIALS AND METHODS

50 patients (34 males, 16 females) in the age group of 18-72 years (mean 42.3 years), having high clinical suspicion of PE, underwent CTPA over a 2 year period. Chest x-ray, arterial blood gas (ABG) analysis, echocardiography were done in all patients. All patients underwent at least one other imaging examination besides CTPA: ventilation perfusion scan, Doppler ultrasound or compression ultrasound (for DVT). All patients were followed for 3 months after completion of the diagnostic work up at baseline. The final diagnosis was achieved by a combination of clinical, imaging, and laboratory analysis, after adequate imaging, laboratory tests, and follow up.

RESULT

CTPA helped correctly identify 29 of 30 patients with PE. In the remaining 20 patients (with no evidence of PE), CT-PA provided additional information (that suggested or confirmed alternate clinical diagnosis) in 15 patients (75%): pleural effusion (n=8), mediastinal or hilar lymphadenopathy (6), pneumonia/airspace consolidation (5), atelectasis/collapse (2), aspergilloma (1), malignancy (1), and others (2).

CONCLUSION

CT-PA is highly specific and sensitive for diagnosis of PE. In addition, in a majority of patients who do not have PE, it also provides important ancillary additional information and helps in making an alternative clinical diagnosis.