Evaluation of Active Disease in a Patient of non-Hodgkin Lymphoma by PET-CT scan over non Significant CT, MRI Findings: a case report

CASE REPORT Evaluation of Active Disease in a Patient of NonHodgkin Lymphoma by PET-CT scan over Non Significant CT, MRI Findings: a case report Abu Bakker Siddique, Mohammad Simoon Salekin, Fatima Begum and Shamim M F Begum National Institute of Nuclear Medicine and Allied Sciences Correspondence Address : Dr. Abu Bakker Siddique, Associate Professor/PMO, PET-CT division, National Institute of Nuclear Medicine & Allied Sciences, BSMMU Campus, Shahbagh, Dhaka. E-mail: ABSTRACT for decades for screening as well as staging for any Imaging modalities like computed tomography (CT) and MRI (magnetic resonance imaging) have been used as diagnostic tools for decades for screening as well as staging for any malignancies but these scans provide anatomical information only. After introduction of 18 Flurodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) hybrid imaging modality as molecular imaging technique by measuring glucose metabolism has revolutionized the detection capability of tumor. PET-CT scan has been used in localization and staging of lymphoma for two decades worldwide. Here, a case of 52 years male, diagnosed case of non-Hodgkin lymphoma (NHL) and received chemotherapy. At the end of therapy results of conventional imaging by CT, MRI suggested complete response of the disease. However, simultaneous PET-CT scan showed extensive active disease. PET-CT hybrid imaging provides additive information about location and extent of the active tumor over CT & MRI, which have limitation to define functional lesion. malignancies. However, due to some limitations Key words: Lymphoma, PET-CT. sometimes CT or MRI alone fails to detect spread of any malignant tumor. Therefore it becomes difficult for accurate restaging as well as to determine the therapeutic response. Thus accurate level of metastasis or level of therapeutic response could not be measured by only anatomical imaging. The PET technology first introduced in 1973 with the first whole body PET in 1977, PET scan had been used as imaging modality since 1990, around the same time PET scans was first applied for assessment for lymphoma. Integrated PETCT as a hybrid imaging modality had been in regular patient’s investigation workup since 2001 (1). Juweid et al were the first for assessment of lymphoma to incorporate FDG/PET into the then standard lymphoma response (2), because 18F FDG PET-CT measures regional glucose uptake, it is not only highly sensitive Bangladesh J. Nucl. Med. Vol. 21 No. 2 July 2018 for metabolically active tissue but also in combination Doi : https://doi.org/10.3329/bjnm.v21i2.40369 with a computerized (CT) scan for localization, spread & response evaluation. Though in patients with INTRODUCTION Hodgkin lymphoma, FDG PET-CT is highly sensitive Lymphomas are a group of hemopoietic disease arising for predicting therapeutic response, in case of non from cells of immune system or form their precursors. Hodgkin lymphoma it is less due primarily to because Amongst the many subtypes of lymphomas, non of heterogeneity and lack of evidence of reasonable Hodgkin lymphoma (NHL) is an aggressive variant. predictive value (3). During the last two decades, Continuous surveillance for evaluation of rapid staging patient imaging workup with 18F FDG PET-CT scan and restaging is needed for planning of next step of continued to increase, particularly in the field of nuclear treatment. Imaging modalities like computed oncology. tomography (CT) and MRI (magnetic resonance Here a case of NHL was presented who was considered imaging) have been used as diagnostic tools as complete response to therapy on CT and 125 Evaluation of Active Disease in a NHL by PET-CT Bangladesh J. Nucl. Med. Vol. 21 No. 2 July 2018 MRI and referred to NINMAS for PET-CT scan for after reviewing all the results concluded that the patient showed complete response to chemotherapy evaluation of disease state. (Figure 1). However, cerebro spinal fluid cytology revealed positive malignant cell; the oncologist re CASE REPORT A 52 years, diabetic male with known case of situs inversus was diagnosed as NHL. Following diagnosis he was referred to oncologist and was prescribed with initial chemotherapeutic regimens. Following 6 cycles of chemotherapy oncologist tried to assess the treatment response & restaged the patient using conventional imaging modalities like CT & MRI. Hisis last chemotherapeutic cycle was uneventful. He underwent MRI of lumbosacral spine, that showed lumbar lordosis, Schmorls’s node at end plate of body of 1st sacral vertebra, early disc desiccation in between 4th and 5th lumbar vertebra and broad based diffuse disc bulge with traversing of 5th lumbar nerve root. CT scan of neck with both pre & post contrast enhancement failed to detect any lymph node in neck (Figure 1). referred the patient to NINMAS for PET-CT evaluation. The patient underwent 18F FDG PET-CT scan following 6 hours of overnight fasting. After administration of 5 m Ci18F FDG the patient was kept in resting quietly for 60 minutes in a shielded room. Imaging was performed with GE-Discovery TM PET-CT series 710 with LYSO crystal scanner. Scan was performed from vertex to mid thigh with 9 bed positions, 2 minutes per bed. Fasting blood glucose level was 5.9 m mol/L at the time of injection. Standardized Uptake Value (SUV) was calculated as SUV bwgm/ml. After careful evaluation following results were noted-extensive focal, linear & diffuse FDG avid lesions (SUV max-13; most intense lesion) throughout the spine, ribs, sternum, scapulae, both hip bones, upper parts of both femora & upper end of right humerus suggested extensive bony meatstases (Figure 2, Figure 3). Figure 1: CT scan (from left to right: Axial, coronal & sagittal view) of 52 years male with NHL after treatment showing no anatomical lesions corresponding PET scan. Situs inversus is seen in coronal view. CT chest on same day suggest ill defined opacities or increased attenuation and striation at different segments of both lower lobes and right middle lobe; which showed compared with significant regression of pulmonary lesion and disappearance of mediastinal lymphadenopathy with absence of any pleural effusion. CT abdomen revealed small cortical cysts in both Figure 2: MIP (Maximum intensity projection) of kidneys with sub centrimeter lymph nodes in abdomen PET-CT scan of 52 years male with NHL after suggesting remarkable regression of size and extension treatment showing extensive FDG avid metastases. abdominal lymphadenopathy. Oncologist 126 Bangladesh J. Nucl. Med. Vol. 21 No. 2 July 2018 Multiple focal hypermetabolic Siddique et. al. (SUVmax-6.0) lesions are scattered in both lobes of liver. Focal FDG lesions were also noted in both sides of neck at level VB (SUVmax-8.0 on left & SUVmax- 7.0 on right side). Multiple focal hypermetabolic (SUVmax -10 most intense) in both para tracheal, retro sternal, subcarinal, para esoph (...truncated)