|Year : 2012 | Volume
| Issue : 2 | Page : 85-91
Abstracts of Oral Presentations
|Date of Web Publication||10-Nov-2012|
|How to cite this article:|
. Abstracts of Oral Presentations. World J Nucl Med 2012;11:85-91
Histopathologic Correlation of 18 F-FDG Uptake in Thyroid Malignancy
B. K. Das, J. Mantil 1
Department of Nuclear Medicine, Utkal Institute of Medical Sciences, Bhubaneswar, Orissa, India, 1 Department of Nuclear Medicine and PET, Kettering Medical Centre, Dayton, Ohio, USA
Background: With the large-scale availability of PET and PET-CT in many centers world over in recent years, this technology has been increasingly used in the diagnosis and management of thyroid malignancy. Most published studies have emphasized the role of PET in patients with high thyroglobulin (Tg) levels and negative radioiodine whole body scans (RIS). However, not much data is available on correlation of FDG uptake and histopathology in malignant disorders of the thyroid gland.
Aim: To analyze 18 F-FDG uptake in different histopathologic types of thyroid malignancy and to establish which type of thyroid cancer will benefit most from FDG uptake study in addition to the conventional diagnostic procedures.
Materials and Methods: Sixty-nine consecutive patients with different histopathology were subjected to 82 studies of 18 F-FDG uptake. In all patients, conventional diagnostic procedures like radioiodine whole body scan (RIS), estimation of Tg level, and CT/MRI/US (wherever indicated) had been performed prior to FDG-PET study. There were 50 females and 19 males in the age group between 11 and 91 years. 18 F-FDG study was performed using the standard PET procedure in either a dedicated PET Camera (ECAT, Siemens) or a PET-CT (Biograph, Siemens) machine. Standard uptake values (SUV) and maximum uptake values (SUVmax) were registered in all suspected lesions. The results of the PET studies were correlated with various histopathologic findings.
Results: In papillary thyroid carcinoma (n = 51), 50 patients were clinically suspected of having recurrence or metastasis (all with high Tg levels, 6 positive, 44 negative RIS). PET study failed to demonstrate any 18 F-FDG uptake in 46% (23/50) of these patients. In follicular thyroid carcinoma (n = 5), four patients were clinically suspected to have metastatic disease with high Tg levels and negative RIS. All showed multiple lesions with high FDG uptake. The one patient with follicular carcinoma arising from struma ovarii in whom Tg was low did not show abnormal FDG uptake. All Hurthle cell carcinoma cases (n = 4) had high Tg levels and negative RIS, but very high FDG uptake (mean SUV: 31.47). In medullary carcinoma (n = 6), five showed no FDG uptake with one having a doubtful lesion (SUV =2.4). Both anaplastic and squamous cell carcinoma (n = 1 each) showed FDG uptake, whereas the adenocarcinoma patient did not show any FDG concentration although there was diffuse 131 I uptake in both lungs. The SUV values in FDG-positive cases of papillary carcinoma were generally low, with maximum measured value of 17.6 in one patient. However, SUV values in follicular and Hurthle cell carcinoma were generally high, with maximum value of 21.8 in follicular and 62.1 in Hurthle cell carcinoma.
Conclusion: 18 F-FDG uptake study has a significant role to play in follicular and Hurthle cell carcinomas, with high rate of lesion detection. This is particularly important as in all cases radioiodine whole body scan was negative. In papillary carcinoma, FDG-PET study could not demonstrate recurrence or metastasis in more than 52% of the cases with negative RIS and high Tg values, and hence is less likely to add significant additional information.
Recurrence of CEA-Secreting Colorectal Malignancies: Can FDG PET-CT Detect Recurrence Earlier than Serial Serum CEA Measurement? A Prospective Study
S. Dash, A. Gupta
Department of Nuclear Medicine, Action Cancer Hospital, New Delhi, India
Aim: To determine the diagnostic capability of FDG PET-CT scan in colorectal malignancy recurrence.
Materials and Methods: A prospective study of 28 consecutive treated patients of colorectal malignancy with normal serum CEA was carried out using whole body FDG PET-CT scan. All patients were biopsy-proven cases of CEA-secreting colorectal malignancies, appropriately treated for the primary malignancy, were in remission and on surveillance. They were with or without any suspicious symptom(s) with normal serum CEA level (<4 ng/ml). FDG-avid lesions were subjected to histopathology or interval FDG PET-CT scan within 8-20 weeks with serum CEA determination to confirm recurrence. Negative PET-CT studies also had interval PET-CT scans 8-20 weeks later and serum CEA measurement to confirm the absence of recurrent disease.
Results: FDG PET-CT detected metabolically active lesions in 13 patients, out of which 11 were true positive and 2 were false positive for recurrence. False-positive lesions had histological evidence of granulomatous abdominopelvic lymphadenopathy, possibly tubercular in etiology. All FDG-negative patients (total 15) had an interval FDG PET-CT scan performed along with measurement of CEA. Nine (out of 15) patients showed no significant interval change (true negative). Five (out of 15) patients had new FDG-avid lesion(s) in the second scan with raised CEA values (true negative). One patient had normal serum CEA with FDG-avid solitary serosal deposit along anastomosis in the second scan, which though present in the first scan, was missed probably due to small size and intense physiological FDG uptake along adjacent bowel mucosa (false negative). On comparison of two scans, the lesion showed increase in size and metabolic activity. Overall, FDG PET-CT showed 91.7% sensitivity, 87.5% specificity, 84.6% positive predictive value, and 93.3% negative predictive value in detecting colorectal malignancy recurrence prior to rise in serum CEA.
Conclusion: Serum CEA is widely used as the only colorectal tumor marker in the post-treatment surveillance. However, normal CEA value does not completely rule out recurrence. FDG PET-CT as an isotropic metabolic imaging modality shows promise to be one-stop approach in the surveillance of large bowel malignancy.
Radionuclide Bone Scintigraphy and SPECT-CT in Evaluation of Rheumatoid Arthritis
S. Pandey, M. Indirani, S. Shelley, P. Alok
Department of Nuclear Medicine, Apollo Hospitals, Chennai, India
Aim: To evaluate the utility of bone scintigraphy and SPECT-CT for diagnosis and evaluation of rheumatoid arthritis (RA).
Study Design: A total of 35 patients referred by rheumatologists for evaluation of polyarthralgia were evaluated. After taking clinical history and examination, whole body planar bone scintigraphy and SPECT-CT of hands, wrists, ankles, and feet was done using Tc-99m labeled MDP. Patients with bilaterally symmetric increased tracer uptake in any of the two joint regions, e.g. elbow/wrist/metacarpophalangeal/ankle/metatarsophalangeal/proximal interphalangeal joints of hands and feet, were diagnosed as RA on bone scintigraphy. The results of planar scintigraphy + SPECT-CT were then compared with the clinical diagnosis of RA (according to the Revised Criteria of American College of Rheumatology). Patients were divided into very early, early, and advanced stage depending on the SPECT-CT findings.
Results: Out of the 35 patients, 29 were diagnosed as RA clinically. Planar bone scintigraphy as well as SPECT-CT was suggestive of RA in 27 patients. Remaining patients were diagnosed as polyarthralgia. Out of 27 patients, 25 had RA and 2 patients were not having RA clinically. Totally four patients of RA were not detected as RA on bone scan. So, true-positive, false-positive, true-negative, and false-negative values are 25, 2, 4, and 4, respectively. The sensitivity was 86.21% and specificity was 66.67%. SPECT-CT categorized the patients with positive scan result into very early (3 patients), early (10 patients), and advanced (14 patients) stage disease (2/3 patients in very early stage category had clinical course of <3 months and 8/10 patients in early stage category had clinical course of 3-12 months).
Conclusion: Bone scintigraphy is a valuable adjuvant tool for diagnosis of RA. SPECT-CT of the affected joint regions helps in staging into early and delayed presentations and, in addition, CT provides information about joint erosion, cortical changes in bones, and in few cases, differentiates degenerative changes from inflammation.
Relevance to Clinical Nuclear Medicine: Bone scan and SPECT-CT being quite sensitive and specific can also be used as an adjuvant tool for diagnosis of RA. As it can detect the disease in very early (the so-called window period) and early stage, it can play valuable role for starting early intensive therapy, and thereby reducing deformity.
Custom-made Prosthesis and Bone Scan - Our Experience in Limb Tumors
K. Kumar, T. Gadepalli, Kathiresan, Vandana, Rangarajan, B. Begum
Cancer Institute (W I A), Adyar, Chennai, Tamil Nadu, India
Aim and Objective: To study the usefulness of bone scan measurements in planning the Custom-made Prosthesis (CMP) in limb salvage surgery.
Study Design: About 16 patients (both males and females) with limb tumors who were fit for surgery have been taken up for this study. Bone scan was done in all these patients for CMP measurements.
Results and Conclusions: Sixteen patients were studied with a spectrum of bone tumors like Ewing's sarcoma, osteosarcoma, chondrosarcoma, hemangioendothelioma, and osteoclastoma. The bone scan was done in all these patients for planning the CMP. Limb salvage surgery is one of the innovative procedures practiced in our centers (MRI, the other modality for measuring length of tumor, cannot be used because it often overestimates due to marrow involvement). Bone scan has the advantage of whole body survey and finding the skip lesion. Hence, it was preferred. After bone scan and workup, patients underwent neoadjuvant chemotherapy before surgery, generally 3-4 courses over a period of 2-3 months. The bone scan measurements were correlated with measurements given in postoperative HPE specimen. In most situations, the size of the lesion on bone scan was observed to be 20-40% larger than pathological specimen. This may be attributed to neoadjuvant chemotherapy and tumor necrosis after bone scan before undertaking the surgery. Only in one situation, the bone scan underestimated the tumor dimension. The prosthesis is planned based on the initial tumor length; concordance of HPE and bone scan measurements is not always possible because of neoadjuvant chemotherapy, hence initial measurements of bone scan can be taken for planning the CMP.
Relevance to Clinical Nuclear Medicine: Bone scan can be used as the modality for planning the prosthesis in cases of limb salvage surgery, which is less expensive and has the advantage of whole body survey to find distant metastases and skip lesions.
Incremental Role of 18 F-FDG PET CT in Hepatocellular Carcinoma
V. Pant, B. I. Sen, R. Verma, A. S. Soin
Department of Nuclear Medicine and Molecular Imaging, Fortis Memorial Research Institute, Sector 44, Gurgaon, Haryana, India, Department of Nuclear Medicine, Mahajan Imaging Centre, Sir Ganga Ram Hospital, and Department of Gastroenterology and Liver Transplant, Medanta the Medicity
Aims and Objectives: In this retrospective study of 100 patients, our aim was to evaluate the incremental role of PET CT in the management of patients with hepatocellular carcinoma (HCC).
Study Design: PET CECT scan of 100 patients of suspected HCC were reviewed. Prior to the scan, patients were asked to fast for 6 h and blood glucose levels were monitored to be less than 200 mg/dl prior to injection of 18 F-FDG. After the FDG injection (370-550 MBq), the patients were instructed to rest comfortably for 45-60 min. All images were acquired using a dedicated GE Discovery PET CT scanner. A triphasic contrast-enhanced CT scan was performed in all the cases, along with the PET CT scan. The PET CT scans of all the patients were reported separately by two nuclear medicine physicians. A stage-wise analysis was done of the entire compiled data. Lesions which demonstrated SUVs greater than the background activity were defined to have increased FDG uptake. Pearson's Chi-square test or Kruskal-Wallis test was used to assess statistical significance. A P value of <0.05 was taken as significant.
Results and Conclusion: In this retrospective study of 100 patients, a higher stage disease was more commonly found in patients with FDG-avid primary tumor group (P < 0.001). The patients with a non-FDG-avid primary tumor were more commonly having a lower stage disease and were found to have less incidence of a metastatic disease or portal vein thrombosis (P < 0.001). The histopathologic findings of the patients who underwent liver transplantation also correlated with the FDG PET CT scan findings as a higher grade tumor was more common in FDG-avid tumor group than in non-FDG-avid tumor group (P < 0.05).
Relevance to Clinical Nuclear Medicine: We can conclude that the 18 FDG PE CT scan can not only be used as a staging tool but also serve as a tool for preoperative pathological staging and prognostication in evaluation of patients with HCC.
Role of Preoperative 18-FDG PET-CT in Early-stage Breast Cancer Management
A. Tewari, P. Shanmuga Sundaram, P. Sundaram, S. S. Pande
Nuclear Medicine, Amrita Institute of Medical Sciences and Research, Kochi, Kerala, India
Background: The aim of this study was to assess the diagnostic and therapeutic impact of preoperative positron emission tomography and computed tomography (PET-CT) in the initial staging of patients with early-stage breast cancer.
Patients and Methods: A total of 72 consecutive patients (age range 24-78 years), of histopathology (infiltrating ductal carcinoma: Lobular carcinoma: Others =49:15:8), newly diagnosed operable breast cancer with tumor size 10-65 mm, were examined preoperatively. All patients underwent conventional assessment modalities (mammography, breast/axillary ultrasound, chest X-ray, and blood samples) and PET-CT. PET-CT identified a primary tumor in all but two patients.
Results: PET-CT solely detected distant metastases (bones, lung, brain, etc.) in 41 patients and new primary cancers (endometrium and lung) in another 2 patients, as well as 11 cases of extra-axillary lymph node involvement. In 11 patients, extra-axillary malignancy was detected by PET-CT only, leading to an upgrade of initial staging in 15% (11/70) and ultimately a modification of planned treatment in 41% (29/70) of patients. PET-CT evaluation led 10 patients of stage IIA in stage IV, 17 out of 19 patients of stage IIB in stage IV, and two patients in stage IIIB, which further modified the treatment plan from an adjuvant to a metastatic approach.
Conclusions: PET-CT is a valuable tool to provide information on extra-axillary lymph node involvement, distant metastases, and other occult primary cancers. Preoperative 18 F-fluorodeoxyglucose PET-CT has a substantial impact on initial staging and on clinical management in patients with early-stage breast cancer.
Incidence and Implications of Delayed Esophageal Transit in Adult Patients with Scintigraphic Evidence of Gastroesophageal Reflux Disease
S. Thangalakshmi, J. Amalchandran, A. Pawaskar, M. Indirani, S. Shelley
Department of Nuclear Medicine, Apollo Hospitals, Chennai, India
Aim: To assess the incidence of delay in esophageal transit (ET) in adult patients with scintigraphically proven gastroesophageal reflux (GER) disease.
Study Design: We retrospectively evaluated 125 patients (male: 88, female: 37) who had evidence of GER on scintigraphic study. The ET study in erect (ETE) and supine (ETS) position and GER scintigraphy were done in the same sitting. The grading of GER and delay in ET in erect and supine position were analyzed.
Results: Out of 125 patients, 98 (78.4%) were found to have delayed ET. Delayed ETS was seen in 41 (41.8%) patients, and both ETE and ETS were delayed in 57 (58.2%) patients. None of the patients had delayed ETE alone. All three patients who had Gr I GER did not show delayed ET in either position. Out of 54 patients having Gr II reflux, 17 (31.8%) showed no delay in ET, 20 (37.03%) showed delayed ETS, and 17 (31.48%) showed delay in ET in both positions. Out of 68 patients having Gr III reflux, 7 (10.2%) showed no delay in ET, 21 (30.88%) showed delayed ETS, and 40 (58.82%) showed delay in both positions.
Conclusion: The incidence (78.4%) of delayed ET was high in patients with GER disease. The incidence of delayed ET increased with severity of GER. Also, the incidence of delay in ETE increased with increase in grade of GER.
Relevance to Clinical Nuclear Medicine: Higher incidence of delayed ET in GER with positive correlation with grade of reflux is suggestive of GER as the primary cause leading to delayed ET. Addition of ET scintigraphy with GER scintigraphy in same sitting appears feasible without any additional cost or radiation burden to the patient. This may give additional information about esophageal dysmotility as well.
Potential of PET-CT in Differentiating Benign and Malignant Cartilaginous Tumors and Grading of Chondrosarcoma
A. Kalshetty, N. Singh Davra, R. Parab
Department of Nuclear Medicine, P. D. Hinduja Hospital, Mumbai, India
Aims and Objectives: To assess the utility of FDG PET-CT with regard to potential of SUV in differentiating chondrosarcomas from benign cartilage tumors and grading of chondrosarcomas.
Materials and Methods: A total of nine patients (two osteochondromas and seven chondrosarcomas) in the age range 6-61 years, consisting of six males and three females, were prospectively studied with FDG PET-CT. All patients underwent PET-CT at initial workup prior to biopsy, and the significance of standardized uptake value (SUV) was evaluated with regard to benign versus malignant lesion, grade of chondrosarcomas, and compared with histopathology. All patients were followed up to a period of 18 months for outcome in terms of relapse.
Results: The two osteochondromas (benign) demonstrated SUV ranging from 1.2 to 1.5, and were congruent with histopathology, with asymptomatic status on follow-up. All seven chondrosarcomas showed SUV >1.3. Further, SUV ranged from 1.3 to 3.4 in two low-grade (grade I) chondrosarcomas, with congruent histopathology, and disease-free status at follow-up. The four grade II chondrosarcomas demonstrated SUV ranging 2.1 to 11, and all four matched the histopathology findings, of which one patient presented with relapse after 13 months. One patient with dedifferentiated chondrosarcoma showed a wide SUV range of 4.6-38.4, which, however, truly matched with the histopathology finding of low-grade chondrosarcoma juxtaposed with predominant high-grade dedifferentiated sarcoma. This patient was lost to follow-up.
Conclusions: Our initial study showed good correlation of FDG PET-CT with histopathology in grading all nine patients, thus impacting the management. PET-CT (SUV) was very useful in differentiating high-grade (grade II and above) chondrosarcomas from low-grade ones, impacting surgical approach decisions. However, there was an overlap between benign osteochondromas and low-grade (grade I) chondrosarcomas, both demonstrating low ranges of SUV, thus causing difficulty in differentiating between the two. On follow-up, FDG PET-CT compared well with outcome as seen by incidence of relapse in high-grade chondrosarcomas.
Clinical Relevance to Nuclear Medicine: Our initial data demonstrate definitive correlation of SUV in FDG PET-CT with histopathology in grading of chondrosarcomas, thus impacting surgical management decisions and further outcome. There is need for larger data with regard to differentiating low-grade chondrosarcomas from osteochondromas.
Role of 18 F-NaF PET-CT Bone Scan in the Evaluation of Patients with Chronic Low Back Pain
B. Prathyusha, N. Kavitha, J. Rao, G. Kalyani, Mansoor
Department of Nuclear Medicine, Apollo Gleneagles Hospital, Hyderabad, India
Aims and Objectives: To assess the role of 18 F-NaF PET-CT bone scan in the evaluation of patients with chronic low back pain.
Study Design: This was a retrospective study done between May 2011 and September 2011. The inclusion criteria were: (a) Both genders above the age of 14 years; (b) patients with low backache of more than 3 months duration; and (c) patients with backache in whom conventional radiography and MRI were performed for diagnostic workup. The exclusion criteria were: (a) Patients with backache of less than 12 weeks duration; (b) patients with backache from known malignancy; and (c) women who were pregnant.
Results and Conclusions: This was a retrospective analysis of 46 patients who had been referred for 18 F-NaF PET-CT scan for the evaluation of chronic low back pain. The diagnosis was inconclusive in majority of the patients on prior conventional radiography and MRI. 18 F-NaF helped in arriving at the diagnosis in many cases which included facet joint arthritis (22%), severe degenerative changes (23%), end plate changes (17%), Paget's disease, insufficiency fractures, enthesitis, sacroiliitis, spondyloarthropathy, skeletal tuberculosis, spondylosis, spondylolisthesis, osteitis condensans ilii, transient osteoporosis of the hip, osteitis pubis, etc.
Relevance to Clinical Nuclear Medicine: It played an important in the evaluation of chronic low back pain by localizing and characterizing the disease, aiding the clinician in the further management. It is a useful adjunct to other imaging modalities when the diagnosis is equivocal.
Comparison of Ga-68 DOTA-TATEPET Scan with CT Scan for the Detection of Bone Metastases in Pediatric Neuroendocrine Tumors
R. Goel, J. Shukla, D. Bansal, A. Bhattacharya, B. Singh, B. R. Mittal
Department of Nuclear Medicine, PGIMER, Chandigarh, India
Aims and Objectives: To compare the diagnostic accuracy of Ga68-DOTATATE PET scan with CT scan for detection of bone metastases in pediatric neuroendocrine tumors.
Study Design: Twenty-five patients (15 males and 10 females; age range 1-19 years; mean age 7.8 years) with histologically confirmed neuroendocrine tumors (16 neuroblastoma, 5 pheochromocytoma, 2 pancreatic NETs, 1 paraganglioma, and 1 ganglioneuroma) were prospectively studied. All patients underwent Ga-68 DOTATATE PET scan and CT scan at the time of diagnosis for primary staging. Imaging results were analyzed on a per-patient and on a per-lesion basis. The criteria for interpreting the scintigraphic lesion as malignant were: clear demarcation of the lesion with tracer accumulation greater than in the liver and higher than physiologic activity, and for CT it was based on the specific appearance of the disease as conventionally described. Conventional imaging, clinical follow-up, and subsequent imaging (wherever available) served as the reference standard. All statistical tests were done using SPSS software 16.0. The statistical significance of differences in sensitivity and specificity between Ga-68 DOTATATE PET scan and CT scan was calculated using the Fischer exact test, and differences on a per-patient and per-lesion basis were evaluated using the McNamara test.
Results and Conclusions: Thirteen of 25 patients had no evidence of bone metastases on any imaging modality or on clinical follow-up, while the remaining 12 patients were true positive for bone metastases on Ga-68 DOTATATE PET, resulting in a sensitivity and specificity of 100% (P < 0.001). Compared to the CT scan, Ga-68 DOTATATE PET detected bone metastases at a significantly higher rate (P = 0.0039). On a per-lesion analysis, out of total 138 lesions detected, only 8 lesions could be detected by CT, while Ga-68 DOTATATE PET detected all 138 lesions, again resulting in a sensitivity and specificity of 100% (P < 0.001). Thus, 68Ga-DOTATATE PET is more useful than conventional CT scan for detection of bone metastases for primary staging in pediatric neuroendocrine tumors.
Relevance to Clinical Nuclear Medicine: Early detection of bone metastases is clinically important because of the high prevalence of bone metastases in patients with advanced neuroendocrine tumors. Also, it is associated with a poor prognosis and is a contraindication for extended surgical resection. Hence, detection of bone metastases by this novel imaging strategy in the form of Ga-68 DOTATATE PET scan offers the possibility of adequate management at an early stage.
Tc- 99m Sestamibi Imaging in Myeloma: A New Look with SPECT-CT
K. Luthra, A. Bhave, R. D. Lele
Lilavati Hospital and Research Centre, Mumbai, India
Background: Tc 99m Sestamibi concentrates in mitochondria of cells and is known to concentrate in certain tumors such as brain tumors, Ca breast, and parathyroid adenomas. We evaluated the role of Sestamibi imaging in multiple myeloma with SPECT-CT imaging.
Materials and Methods: We performed 97 studies on 74 diagnosed cases of myeloma. Nineteen patients had a single follow-up study, three had two follow-ups, and one patient had three follow-up scans. The patients were injected with 15 mCi Tc 99m Sestamibi i.v. Whole body planar scans were obtained with a dual-head gamma camera at 10 min post injection. SPECT-CT imaging from mid-skull to mid-thigh level was done. 2 h delayed whole body scans were also acquired.
Results: Myeloma lesions showed good concentration of Tc-99m Sestamibi. The physiological uptake of Tc-Sestamibi by myocardium, salivary glands, intestinal and urinary tracts, which was a hindrance for its earlier use as a tumor imaging agent, were very well overcome by the use of SPECT-CT scanning, which allowed excellent localization of tracer activity in the marrow lesions. Being a whole body scan, it localized diffuse or localized marrow involvement anywhere in the body, with some lesions localized even in the lower extremities. Soft tissue involvement by disease was also seen. Additionally, the CT scan component of SPECT-CT allowed visualization of osteolytic lesions of myeloma, which may or may not concentrate tracer, indicating whether these were active or old burnt-out lesions. The Sestamibi scan findings showed good correlation with the clinical picture and serum markers such as β2 microglobulin levels in newly diagnosed cases and those on follow-up. Patients of monoclonal gammopathy of unknown significance (MGUS) showed poor concentration of Sestamibi. Where comparison was available, Sestamibi scan showed the lesions demonstrated on MRI or PET-CT and occasionally showed additional areas of disease.
Conclusion: Tc-99m Sestamibi scanning is very useful and economical for evaluating the extent of disease in multiple myeloma.
PET-CT Guided Percutaneous Biopsy: Initial Experience using an Intraprocedural Single-Bed PET-CT Acquisition
I. B. Sen, V. Pant, S. Arora 1 , Jyotsna, Sunil, S. Pandey 1
Department of Nuclear Medicine, Fortis Memorial Research Institute, Gurgaon, Delhi NCR, 1 Artemis Health Institute, Gurgaon, Delhi NCR, India
Background: Positron emission tomography (PET)-computed tomography (CT) guided percutaneous biopsy is a promising tool to obtain representative histological samples from lesions detected with PET, which may have little or no correlative CT findings, as also in heterogeneous lesions which demonstrate areas of internal necrosis. We developed a protocol for multimodal image-guided interventions using an integrated PET-CT machine, and herein report our experience in 55 patients where this protocol was used to perform image-guided percutaneous biopsies.
Purpose: To establish the feasibility of using an intraprocedural combined PET-CT guided biopsy of masses to establish histological diagnosis.
Materials and Methods: Fifty-five participants were selected from among the patients referred to the nuclear medicine department for whole body PET-CT scans and PET/CT guided percutaneous biopsy. All participants provided written informed consent before participating in the study. Participants were aged 18 years or older and were found at presentation to have an FDG-avid mass that either was not visible or had margins that were not clearly defined at non-enhanced CT. We also included patients with a mass that showed FDG uptake that was limited to or greater in one part of the mass. Only lesions of potential impact on the further therapeutic concept were biopsied. The PET-CT guided biopsy procedure was as follows. The procedure was carried out under local anesthesia using all aseptic precautions. A single-bed PET-CT acquisition was performed in the biopsy position to localize the lesion. The needle was introduced under CT guidance in a step-by-step technique. The correct needle position in the center of the FDG-avid lesion was assured by repetition of a single-bed PET-CT acquisition before sampling. If necessary, the biopsy needle was repositioned depending on the result of the control images.
Data Analysis: The data were retrospectively analyzed using the following parameters: (1) Time taken to complete the procedure; (2) ability to obtain representative pathological sample; and (3) major adverse effects.
Results: The mean time taken for the entire biopsy procedure was 18 min. The metabolically active part of lesions was accurately targeted in all patients and representative samples were obtained in 51 of the 55 biopsies performed (92%). No major adverse effects occurred.
Conclusion: We conclude that PET-CT guidance for interventions is feasible and may be promising to optimize the diagnostic yield of CT-guided interventions and to make metabolically active lesions without morphological correlate accessible to percutaneous interventions.
Role of FDG PET-CT in Treatment Response Evaluation in Skeletal Tuberculosis
S. Dureja, I. B. Sen 1 , S. Acharya 2
Department of Nuclear Medicine, Max Super-Speciality Hospital, Saket, New Delhi, 1 Fortis Memorial Research Institute, Gurgaon, Haryana, 2 Sir Ganga Ram Hospital, Rajinder Nagar, New Delhi, India
Aims and Objectives: (1) To investigate the utility of PET-CT as a diagnostic tool to diagnose musculoskeletal tuberculosis (TB) and to study the ability of FDG PET-CT to detect occult unsuspected multifocal disease. (2) To assess the role of FDG PET-CT scanning in response evaluation to antitubercular therapy (ATT), including its role in assessing the metabolic response to ATT during the course of treatment, and to evaluate if change in FDG uptake in known tubercular disease correlates with accepted clinical markers of response evaluation.
Study Design: This was a prospective study done on patients with histopathologic and/or radiological diagnosis of skeletal TB. Demographic data, clinical and treatment history, general and systemic examination findings, laboratory parameters, and relevant radiological imaging findings of all the patients were recorded. Thirty-three patients with a histopathologically confirmed diagnosis of skeletal TB underwent a baseline contrast-enhanced whole body FDG PET-CECT scan before initiation of ATT, followed by scans at 6 months and 12 months during the course of treatment and at 18 months or at the end of ATT, as determined by the treating clinician. Each patient's clinical and imaging data were compiled temporally. Since few enrolled patients were lost to follow-up, the data were divided into groups according to the length of follow-up. Descriptive statistics was used to summarize the clinical and demographic profiles of all the patients. The data for patients were segregated into groups according to four time points of observation. The SUVmax, VAS pain score, ESR, and ECOG scale scores were arranged into these four groups for comparison. Mean SUVmax, VAS score, and ESR were calculated for each of the groups. The mean change in SUVmax at various time points was calculated using the Wilcoxon signed-rank test. Further, the correlation between percentage change in mean SUVmax at different time points during ATT with percentage change in clinical response indicators, viz. ESR, ECOG score, and VAS pain score, was measured. Data were cross-tabulated for percent changes, and Spearman's rank correlation test for non-parametric data was used for each dataset.
Results and Conclusions: Incidence of occult non-contiguous tubercular involvement in skeletal TB is higher than detected by conventional regional imaging techniques. SUVmax can be taken as a reliable marker for serial quantification of metabolic activity in an inflammatory disease process like TB. This may translate into a potential role for FDG as an imaging biomarker for non-invasive response evaluation in skeletal TB. Further, FDG PET will serve as a useful tool for early detection of multidrug resistance, thus significantly reducing lag period in diagnosis and its associated morbidity.
Relevance to Clinical Nuclear Medicine: There are conflicting guidelines and variations in clinical practice in the management of bone TB, including spinal TB. Presently, there are no guidelines on the appropriate imaging modality and frequency of use in the follow-up of spinal TB. With this study, we set out to determine the role of FDG PET-CT as an imaging marker for metabolic response to ATT in musculoskeletal TB. We also aimed to define whether FDG PET-CT can help us guide in determining the treatment end point after conventional therapeutic regimens.
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