Role of rhenium-188 tin colloid radiosynovectomy in patients with inflammatory knee joint conditions refractory to conventional therapy

The effect of radiation synovectomy with phosphorus-32 on the pain and swelling in 31 RA patients with resistant monoarthritis of the knee

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by symmetric polyarthritis. RA is routinely treated by various systemic drugs; on the other hand, administration of intra-articular corticosteroids or different types of synovectomies can be used in case of systemic medication's failure. Chemical, radio isotopic, and surgical synovectomies are being used as therapeutic options for chronic synovitis to improve joint function. Chemical synovectomy is not well tolerated, and the long-term response is relatively low. Surgical synovectomy has a better success rate, but it recommends higher expenses. In radiation synovectomy, radioactive labeled particles are applied directly in the articular cavity, followed by homogeneous distribution in joint. Next, the radioactive particles are transported in the depth of synovia and phagocytized by inflammatory cells. Finally, the radiation leads to fibrosis and sclerosis of formerly inflamed synovial membrane; thus, it stops the inflammation and reduces the symptoms. It has a success rate of 40-100% and its effect can be similar to surgical synovectomy.

MATERIALS AND METHODS

Thirty-one patients with resistant monoarthritis of the knee were enrolled in this study. One millicurie of phosphorus-32 was injected into patients' knee via US guide. Saline was injected afterwards to prevent leakage. Direct pressure was performed after removing the needle and the knee was flexed slowly to ensure homogenous distribution and fixed with a splint for 1 to 2 weeks. Patients were followed up after 2 weeks, 1 month, 2 months, and 6 months. The following variables were assessed by the treating rheumatologist: patients' pain, joint tenderness, effusion, and ROM. At the time of injection and after the first week, patients were investigated for any complication including infection, necrosis, pain, and swelling. The effect of clinical characteristics and demographic data on existing complications and the changes of pain, joint tenderness, effusion, and ROM was assessed.

RESULTS

Thirty-one patients with the mean age of 54.5 ± 12.2 years and the mean disease duration of 12 ± 6.5 years were enrolled in this study. Mean DAS-28 ESR score for our patients was 4 ± 0.7. The pain, effusion, and reduced ROM were decreased significantly after all follow-up intervals. Knee tenderness was not affected in the first 2 weeks, but it was reduced significantly after 1, 2, and 6 months. No serious complications like infection and necrosis were reported through our study. 51.6% and 54.8% of our patients reported pain and swelling in the administration site. Furthermore, 19.4% and 16.1% of patients reported deterioration of pain and effusion in the first week of injection.

CONCLUSION

In our study, we demonstrated that pain, tenderness, effusion, and ROM are improved after radiation synovectomy with phosphorus-32. We also showed that there was no serious adverse effect like infection and necrosis. However, more than half of our patients experienced pain and swelling of injection site at the time of administration. Key points • We demonstrated the efficacy of radiation synovectomy as a medication for monoarthritis. • The results of our study can lead to a bigger clinical trial to assess the benefits and adverse effects of radiation synovectomy in comparison to treatment with local or systemic corticosteroids.

Operational nuclear research reactors in the Asia-Pacific with potential for medical radionuclide production

Personalised cancer treatment is of growing importance and can be achieved via targeted radionuclide therapy. Radionuclides with theranostic properties are proving to be clinically effective and are widely used because diagnostic imaging and therapy can be accomplished using a single formulation that avoids additional procedures and unnecessary radiation burden to the patient. For diagnostic imaging, single photon emission computed tomography (SPECT) or positron emission tomography (PET) is used to obtain functional information noninvasively by detecting the gamma (γ) rays emitted from the radionuclide. For therapeutics, high linear energy transfer (LET) radiations such as alpha (α), beta (β - ) or Auger electrons are used to kill cancerous cells in close proximity, whereas sparing the normal tissues surrounding the malignant tumour cells. One of the most important factors that lead to the sustainable development of nuclear medicine is the availability of functional radiopharmaceuticals. Nuclear research reactors play a vital role in the production of medical radionuclides for incorporation into clinical radiopharmaceuticals. The disruption of medical radionuclide supplies in recent years has highlighted the importance of ongoing research reactor operation. This article reviews the current status of operational nuclear research reactors in the Asia-Pacific region that have the potential for medical radionuclide production. It also discusses the different types of nuclear research reactors, their operating power, and the effects of thermal neutron flux in producing desirable radionuclides with high specific activity for clinical applications.

Radiosynoviorthesis: almost seventy years of experience but still somewhat fameless

Radiosynoviorthesis (RSO) or radiation synovectomy has been practiced for more than half a century, but in many parts of the world, it is still relatively unknown and not used to its full potential in the standard care for chronic, persistent or recurrent synovitis. The working mechanism of RSO is simple yet elegant. Radiopharmaceutical particles are, after injection in the affected synovial joint, gobbled up by phagocytizing subsynovial inflammatory cells. As a consequence, the synovium will be irradiated locally resulting in synovial cell necrosis and inhibition of cell proliferation, which eventually leads to a decrease in the inflammatory response in the joint cavity. In this review RSO is once again brought to the attention and common indications for RSO are discussed. Also, appropriate activities of the administrated radiopharmaceuticals and coadministrated glucocorticoids are provided. Furthermore, a detailed database-assisted chronological overview of published literature of RSO in inflammatory and non-inflammatory diseases, like rheumatoid arthritis, psoriatic arthritis, osteoarthritis and osteochrondomatosis, hemophilic hemarthrosis and pigmented villonodular synovitis (PVNS) is provided. Based upon the published literature an indication of level of evidence of RSO is discussed. There is evidence that RSO is effective in persistent synovitis in patients with a variety of causes for synovitis, although the effectiveness seems to decrease over time. In these patients, RSO may not be used to its full potential in many parts of the world. Results in of RSO in hemophilia patients with hemarthrosis are favourable, however the evidence for the effectiveness of RSO in these patients is less firm and mainly based on case series. The evidence for the efficacy of RSO as adjuvant therapy in PVNS is, at best, of very low quality.

Role of 18F-FDG PET/CT in the Assessment of Response to Antitubercular Chemotherapy and Identification of Treatment Endpoint in Patients With Tuberculosis of the Joints: A Pilot Study

AIMS

The aim of this study was to explore the utility of 18F-FDG PET/CT in the assessment of response to antitubercular treatment (ATT) and identification of treatment endpoint.

PATIENTS AND METHODS

Forty patients (mean age, 35.3 years; 27 men) with clinically, radiologically, and histopathologically proven joint tuberculosis prospectively underwent clinical, biochemical, and PET/CT evaluation at baseline and after ~6, 12, and 18 months of ATT. Two patients were lost to follow-up, and 1 defaulted treatment. The remaining 37 were followed up until complete response (CR) was achieved. Images were visually and quantitatively (SUVmax ratio and metabolically active disease volume [MV]) evaluated by 2 experienced nuclear medicine physicians.

RESULTS

Knee (n = 18) and ankle (n = 7) were the most frequently involved sites. The median MV and SUVmax ratio at baseline were 85.10 mL and 7.21, respectively. Five patients had noncontiguous vertebral involvement, 12 had pulmonary lesions, 2 had abscesses, 6 had mediastinal, and 30 had local lymph nodal involvement. Complete response was seen in 1/39, 11/37, and 30/37 patients after 6, 12, and 18 months of ATT. Significant reductions in visual analog scale score, tenderness, joint swelling, SUVmax ratios, and MVs (Friedman test, P < 0.001) were seen after each follow-up. The median time-to-CR in skeletal lesions was significantly longer than extraskeletal lesions (591 vs 409 days; Wilcoxon signed-rank test, P < 0.001). Time-to-CR in joint lesions positively correlated with MV at first follow-up (Pearson = 0.452, P = 0.005) and negatively correlated with percentage change in MV (first follow-up from baseline) (Pearson = -0.620, P < 0.001). ROC analysis yielded a cutoff of ≤71% reduction in MV at first follow-up (80.8% sensitivity, 81.8% specificity) to predict extension of ATT beyond 12 months. Using ROC analysis at second follow-up, a cutoff of ≤12.67 mL (for CR) was derived and was validated in patients at the third follow-up, with an accuracy of 84.4%. Patients with CR in PET/CT maintained disease-free state during a mean follow-up of 271 days.

CONCLUSIONS

18F-FDG PET/CT is an excellent tool in estimating total disease burden, assessing response to ATT and identification of treatment endpoint in joint tuberculosis.

FDG-PETCT versus contrast-enhanced computed tomography in diagnosis of post-therapeutic colorectal cancer recurrence and metastases

Background

This study was designed to assess the role of 18F-FDG CT was able to detect additional/CT in post-therapeutic surveillance of colorectal cancer patients as compared with contrast-enhanced CT to allow early detection of recurrent and metastatic cases amenable for curative surgery and thus improve the overall survival of patients.

Results

Of the total 100 patients, 70 proved to have metastasis or local recurrent disease by the standard reference modalities. One hundred eighty-two diseased regions were detected in these 70 patients. PET/CT was positive in 174 regions (95.6%) whereas CECT was positive in 118 regions (64.8%). PET/CT was superior to CECT in detection of hepatic focal lesions, metastatic lymph nodes, pulmonary metastases, and peritoneal and suprarenal metastases whereas both were equal in detection of osseous deposits. CECT detected four lesions that were missed by PET/CT, and these were hepatic metastases from mucinous adenocarcinoma.

Conclusion

PET/CT is a better method to evaluate post-therapeutic colorectal cancer patients. It detected viable residual tumor cells in operative bed scar, small LNs, hepatic focal lesions, peritoneal deposits, pulmonary masses, bone deposits, and suprarenal deposits with significantly higher specificity and sensitivity than CECT avoiding unnecessary surgeries.

Neutron-activated theranostic radionuclides for nuclear medicine

Theranostics in nuclear medicine refers to personalized patient management that involves targeted therapy and diagnostic imaging using a single or combination of radionuclide (s). The radionuclides emit both alpha (α) or beta (β-) particles and gamma (γ) rays which possess therapeutic and diagnostic capabilities, respectively. However, the production of these radionuclides often faces difficulties due to high cost, complexity of preparation methods and that the products are often sourced far from the healthcare facilities, hence losing activity due to radioactive decay during transportation. Subject to the availability of a nuclear reactor within an accessible distance from healthcare facilities, neutron activation is the most practical and cost-effective route to produce radionuclides suitable for theranostic purposes. Holmium-166 (166Ho), Lutetium-177 (177Lu), Rhenium-186 (186Re), Rhenium-188 (188Re) and Samarium-153 (153Sm) are some of the most promising neutron-activated radionuclides that are currently in clinical practice and undergoing clinical research for theranostic applications. The aim of this paper is to review the physical characteristics, current clinical applications and future prospects of these neutron activated radionuclides in theranostics. The production, physical properties, validated clinical applications and clinical studies for each neutron-activated radionuclide suitable for theranostic use in nuclear medicine are reviewed in this paper.

Comparison of Lutetium-177 tin colloid and Rhenium-188 tin colloid radiosynovectomy in chronic knee arthritis

OBJECTIVE

To assess the role of Lutetium-177(Lu-177) tin colloid for radiosynovectomy and compare it with Rhenium-188 (Re-188) tin colloid radiosynovectomy for alleviation of pain in patients with chronic inflammatory arthritis of knee.

METHODS

Patients of chronic inflammatory arthritis of the knee underwent pretherapeutic evaluation in a form of knee ultrasonogram, bone scan and clinical evaluation. Fifty-seven recruited patients were allocated at random to receive either intraarticular injections of Lu-177 tin colloid or Re-188 tin colloid. Eventually, 27 patients received Re-188 tin colloid and 30 patients received Lu-177 tin colloid. The joint was then immobilized for 2 days. Response evaluation was done using knee ultrasound, bone scan and clinical findings.

RESULT

Of 30, 20 patients responded to radiosynovectomy in the Lu-177 tin colloid group compared to 21/27 patients in the Re-188 tin colloid group.

CONCLUSION

Lu-177 tin colloid is an effective alternative to Re-188 tin colloid for radiosynovectomy in patients with chronic inflammatory knee arthritis.

Prospective evaluation of phosphorus-32 radiation synovectomy in patients with severe and chronic rheumatoid arthritis unresponsive to conventional medical treatment

OBJECTIVES

To determine the efficacy of Phosphorus-32 radiation synovectomy in the treatment of patients with severe rheumatoid arthritis (RA) unresponsive to systematic or local medical therapy.

METHODS

Twenty-three knees in 16 patients with severe chronic RA were prospectively treated by intra-articular installation of Phosphorus-32 and evaluated at 1, 3, 6, and 12 months. The Western Ontario and McMaster Universities Arthritis index (WOMAC), visual analog scale (VAS), Health Assessment Questionnaire (HAQ), pain scale, and grade of joint effusion and tenderness were assessed. At the 12-month time interval, the treated knees were classified into four categories: excellent response (no symptoms), good response (significant reduction of symptoms), moderate response (slight decrease), and poor response (no change or worsening).

RESULTS

Excellent response or good response was observed in 13/23 (56.5%) of the treated knees, moderate response in 2/23 (8.7%) of the treated knees, and poor response in 8/23 (34.8%) of the treated knees. The grades of effusion and tenderness were significantly decreased one-month posttreatment (P< 0.05); however, these changes did not persist at other time intervals (P > 0.05). There was a significant improvement in the HAQ, WOMAC, VAS, and pain scores at all time points compared with baseline, including at the 12-month time interval (P < 0.05).

CONCLUSION

Phosphorus-32 radiosynovectomy is an effective therapeutic treatment for patients with RA of the knee unresponsive to conventional pharmacotherapy.

Intraarticular injection of a Tin-117 m radiosynoviorthesis agent in normal canine elbows causes no adverse effects

This longitudinal prospective exploratory study used serial measurements in five dogs to evaluate safety and retention of a tin-117 m (^117m Sn) colloid after intra-articular injection in normal elbow joints. Each dog was deemed healthy based on physical examination, laboratory results, and radiographic evaluation of both elbows. While anesthetized, each received an MRI of both elbows, followed by fluorine-18 fluorodeoxyglucose positron emission tomography scans of both elbow joints and associated lymph nodes. Joint fluid (0.5-1.0 mL) was withdrawn aseptically from the left elbow joint, followed by intra-articular injection of ^117m Sn colloid (92.5 MBq; 1-1.5 ml). Post-injection assessments included blood counts, serum chemistry panels, urinalyses, radiographs, joint fluid analyses, MRI/positron emission tomography scans, scintigraphy, and biodistribution scans. On day 45-47, each dog was euthanized and a complete postmortem examination was performed. Tissue samples were submitted for histopathology and radioisotope retention studies. Left elbow joints were decalcified and sectioned for future autoradiography. Scintigraphy, 1 day after injection, indicated slight radioisotope escape from the joint to regional lymph nodes. Serial blood, urine, feces, and organ counts indicated >99.1% of the ^117m Sn activity was retained in the joint for 45-47 days. Radiation output levels were below patient release levels the day following injection. Maximum standard uptake value for the injected joint decreased. Joint fluid cytology was unchanged. No dog exhibited lameness during the study. Absence of joint damage and lack of systemic effects after injection of the ^117m Sn colloid in normal canine elbow joints indicate that this agent may be safely used for radiosynoviorthesis in dogs with osteoarthritis.

Lutetium-177 tin colloid radiosynovectomy in patients with inflammatory knee joint conditions intractable to prevailing therapy

OBJECTIVE

To evaluate the treatment response of lutetium-177 tin colloid radiosynovectomy (Lu-RSV) in patients with inflammatory knee joint conditions refractory to conventional treatment.

PATIENTS AND METHODS

Overall, 29 knee joints in 29 patients with chronic synovitis caused by various inflammatory knee joint diseases refractory to conventional therapy were included in this prospective study. All patients were assessed clinically for pain, tenderness, joint swelling, mobility, analgesic intake, and blood pool activity on bone scan. Different scores were assigned to all these parameters. RSV of knee joint was done using intra-articular injection of Lu tin colloid. Response was assessed at 3 months using various clinical parameter scores and blood pool bone scan as mentioned before and categorized as responders and nonresponders on the basis of change in percentage of cumulative scores.

RESULTS

Of the 29 joints, 21 were responders and eight were nonresponders at 3 months after RSV. There was a statistically significant reduction in clinical parameters cumulative scores at follow-up when compared with baseline (P<0.0001). Blood pool scintigraphy also showed decrease in blood pool activity compared with the baseline. There was statistically significant association between the responder group and absence of radiological abnormality.

CONCLUSION

Lu tin colloid synovectomy is a useful treatment modality in patients with chronic inflammatory knee joint conditions refractory to conventional treatment. Patients with shorter duration of disease and normal or minor radiographic findings are better candidates for RSV.

Potential Adjunctive Role of Radiosynovectomy in Primary Synovial Osteochondromatosis of the Knee: A Case Report

Primary synovial osteochondromatosis (PSOC) is a rare but clinically significant cause of morbidity especially in the male population. Surgery is the primary treatment of choice, but the recurrence rate is reported to be high. Moreover, the presence of widespread loose bodies makes it a cumbersome procedure. The complete removal of the disease is tough at times and results in early recurrence. Radiosynovectomy is an established technique for treating various joint arthropathies. The role of radiosynovectomy in case of PSOC has not yet been explored. This case report described the case of a young male with PSOC of the knee joint who was treated with radiosynovectomy for pain relief. The patient reported complete relief from the pain along with significant improvement in joint mobility. The post-therapy three-phase bone scan also validated the reduction in joint inflammation. The patient was taken for surgical removal of the redundant loose bodies after a significant improvement in the pain and reduction in inflammation. Post-therapy radiation fibrosis of the synovium also helped in the en bloc removal of the disease. The role of radiosynovectomy in PSOC needs to be further explored concerning its potential role as an adjuvant to surgical procedures.

Formulation and characterization of lutetium-177-labeled stannous (tin) colloid for radiosynovectomy

OBJECTIVE

Easy large-scale production, easy availability, cost-effectiveness, long half-life, and favorable radiation characteristics have made lutetium-177 (Lu) a preferred radionuclide for use in therapy. Lutetium-177-labeled stannous (Lu-Sn) colloid particles were formulated for application in radiosynovectomy, followed by in-vitro and in-vivo characterization.

METHODS

Stannous chloride (SnCl2) solution and Lu were heated together, the pH was adjusted, and the particles were recovered by centrifugation. The heating time and amount of SnCl2 were varied to optimize the labeling protocol. The labeling efficiency (LE) and radiochemical purity (RCP) of the product were determined. The size and shape of the particles were determined by means of electron microscopy. In-vitro stability was tested in PBS and synovial fluid, and in-vivo stability was tested in humans.

RESULTS

LE and RCP were greater than 95% and ∼99% (Rf=0-0.1), respectively. Aggregated colloidal particles were spherical (mean size: 241±47 nm). The product was stable in vitro for up to 7 days in PBS as well as in synovial fluid. Injection of the product into the infected knee joint of a patient resulted in its homogenous distribution in the intra-articular space, as seen on the scan. No leakage of activity was seen outside the knee joint even 7 days after injection, indicating good tracer binding and in-vivo stability.

CONCLUSION

Lu-Sn colloid was successfully prepared with a high LE (>95%) and high RCP (99%) under optimized reaction conditions. Because of the numerous benefits of Lu and the ease of preparation of tin colloid particles, Lu-Sn colloid particles are significantly superior to its currently available counterparts for use in radiosynovectomy.

Failed Radiation Synovectomy in Diseased Knee Joint with Missed Tuberculous Synovitis

The authors in this case report highlight the poor outcome of radiation synovectomy (RSV) for repeated knee joint effusion in a patient with histopathologically proven nonspecific arthritis. There was partial response initially following RSV but later follow-up showed recurrence in joint effusion with limited and painful mobility of the knee joint. Subsequent surgical synovectomy and histopathological examination showed it to be tubercular in origin. Thus in a country endemic for tuberculosis, an alternative infective etiology should also be kept in mind before subjecting the patient to RSV.

Hydroxyapatite (HA) microparticles labeled with (32)P - A promising option in the radiation synovectomy for inflamed joints

In the present article we describe a systematic approach pursued for the synthesis of (32)P-labeled hydroxyapatite (HA) microparticles (1-10µm size range) using no carrier added (NCA) (32)P produced in a nuclear reactor and animal evaluation of its utility as an expected viable radiopharmaceutical for the treatment of pain intensive arthrosis. NCA (32)P was produced via the (32)S(n,p)(32)P route in nuclear reactor with high radionuclidic purity (99.95±0.01%, n=5). Phosphorus-32-labeled hydroxyapatite microparticles (1-10µm size range) were synthesized with high radiochemical purity (99.0±0.3% n=12) under optimized conditions and the formulation showed excellent in vitro stability in saline as well as in rat serum. Intra-articular administration of the radiolabeled particles in the knee joints of normal Wistar rats showed near-complete retention of activity within the synovial cavity upto 1 month post-administration. The radiochemical formulation thus demonstrated promising features as a radiopharmaceutical for treatment of arthritis with excellent logistic advantage for shipment to sites distant from the production facility thanks to the suitable nuclear decay properties of (32)P.

Therapeutic radionuclides in nuclear medicine: current and future prospects

The potential use of radionuclides in therapy has been recognized for many decades. A number of radionuclides, such as iodine-131 ((131)I), phosphorous-32 ((32)P), strontium-90 ((90)Sr), and yttrium-90 ((90)Y), have been used successfully for the treatment of many benign and malignant disorders. Recently, the rapid growth of this branch of nuclear medicine has been stimulated by the introduction of a number of new radionuclides and radiopharmaceuticals for the treatment of metastatic bone pain and neuroendocrine and other malignant or non-malignant tumours. Today, the field of radionuclide therapy is enjoying an exciting phase and is poised for greater growth and development in the coming years. For example, in Asia, the high prevalence of thyroid and liver diseases has prompted many novel developments and clinical trials using targeted radionuclide therapy. This paper reviews the characteristics and clinical applications of the commonly available therapeutic radionuclides, as well as the problems and issues involved in translating novel radionuclides into clinical therapies.

Radiosynovectomy of Proximal Interphalangeal Joint Synovitis in Rheumatoid Arthritis Treated with Rhenium-188 Labeled Tin-colloid and Imaging with Single-photon Emission Computerized Tomography/Computed Tomography: A First Case Report

Rheumatoid arthritis (RA) is a chronic disease that is mainly characterized by the asymmetric erosive synovitis, particularly affecting peripheral joints. Radiation synovectomy or radiosynovectomy (RSV), also known as radiosynoviorthesis was first described in 1950's as an adjuvant treatment for RA. RSV is based on the irradiation of the joint synovium by the intra-articular administration of various β-emitting radiopharmaceuticals. As a generator-produced β-emitting radionuclide, the importance of rhenium-188 (Re-188) for radionuclide therapy is increasing rapidly. There are previous reports which used Re-188 tin colloid in knee joint synovitis, but use of Re-188 tin colloid in small joint is not yet reported. We describe the use of Re-188 tin colloid in a 45-year-old female who presented with right 4^th proximal interphalangeal joint synovitis due to rheumatoid arthritis.

Detection of resectable recurrences in colorectal cancer patients with 2-[18F]fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography

PURPOSE

To evaluate the usefulness of 2-[(18)F]fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in the early detection of resectable recurrences of colorectal cancer (CRC) and the impacts on the clinical disease management.

METHODS

FDG-PET/CT was performed on patients with elevated serum carcinoembryonic antigen (CEA) levels >5 ng/mL (Group 1) or suspicious recurrences without rise in serum CEA levels (Group 2). The results were analyzed on the basis of histological data, disease progression, and/or clinical follow-up. Recurrence was defined as evidence of recurrent lesions within 6 months of the FDG-PET/CT scan. Resectable recurrences and changes in management were calculated based on medical records.

RESULTS

In our study, 128 consecutive FDG-PET/CT analyses (n=49 in Group 1 and n=79 in Group 2) were performed on 96 recruited patients. Recurrences were proven in 63. The overall sensitivity, specificity, and accuracy of FDG-PET/CT were 98.4%, 89.2%, and 93.8%, respectively, and were 100%, 88.9%, and 95.9% in Group 1 and 96.9% and 89.4% and 92.4% in Group 2, respectively. Surgical resections were performed in 38.7% (12/31) of Group 1 patients and 53.1% (17/32) of Group 2 patients. FDG-PET/CT induced changes in planned management in 48.4% (62/128) of all patients, which included 63.3% (31/49) of Group 1 patients and 39.2% (31/79) of Group 2 patients (p=0.008). After a follow-up, 3.4% (1/29) of patients who underwent surgical resection of recurrent lesions and 34.3% (11/34) patients who did not undergo resection died at the end of study (p=0.004).

CONCLUSIONS

The surgical resection of limited recurrent disease, as determined by FDG-PET/CT, improves the survival of CRC patients. FDG-PET/CT should be performed not only in patients with elevated serum CEA levels, but also in those in whom recurrences are suspected to improve the early detection of resectable disease.

The utility of FDG-PET/CT as an effective tool for detecting recurrent colorectal cancer regardless of serum CEA levels

PURPOSE

Tumor recurrence of colorectal cancers (CRC) is generally followed up by analyses of the serum carcinoembryonic antigen (CEA) levels. However, recent evidence suggests that tumor recurrence can also be visualized by 18F-fluoro-deoxyglucose emission tomography/computed tomography (FDG-PET/CT) in patients with normal CEA levels. We retrospectively evaluated the diagnostic performance of FDG-PET/CT in patients with suspected recurrence of CRC by comparing PET/CT performance in patients with normal CEA levels with PET/CT performance in patients with elevated CEA levels.

METHODS

A total of 235 patients with CRC who had been treated with surgery and/or chemotherapy/radiotherapy underwent PET/CT for the detection of tumor recurrence. The patients [96 females and 139 males; age (mean ± SD) 59.9 ± 12.6 years; range 18-85] were divided into 2 groups based on whether their CEA levels were normal (<5 ng/ml) (Group 1, n = 118) or elevated (>5 ng/ml) (Group 2, n = 117). All of the patients had suspected recurrence based on raised CEA levels, clinical symptoms, and/or tumor detection using other imaging modalities.

RESULTS

Of the 235 patients, 172 (73.1 %) had disease recurrence confirmed by a pathological examination (either biopsy or surgical exploration) or clinical follow-up studies. The FDG-PET/CT study yielded a true positive in detecting recurrence in 169 (71.9 %) patients, a true negative in 53 (22.5 %) patients, a false negative in 3 (1.2 %) patients and a false positive in 10 (4.2 %) patients. CRC recurrence was detected in 64.4 % (76/118) and 88 % (103/117) patients in Group 1 and Group 2 with FDG-PET/CT, respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of the FDG-PET/CT study for establishing recurrence were 100, 84, 89.4, 100 and 93.2 %, respectively, for Group 1; by contrast, these parameters were 97.1, 84.6, 98, 78.5 and 95.7 %, respectively, for Group 2. The number of patients with hepatic and extra-hepatic metastases, such as lung and abdominal lymph node metastasis, detected with FDG-PET/CT was significantly different in Group 1 than in Group 2; however, the number of patients with local recurrence and peritoneal implants detected with FDG-PET/CT was not different between the two groups.

CONCLUSIONS

FDG-PET/CT can accurately detect tumor recurrence in patients with suspected recurrent CRC, even for patients with normal CEA levels.

¹⁵³Sm-HM for arthritic knee pain. Estimated dosimetry

Osteoarthritis is the most common type of arthropathy and after cardiovascular diseases is the most disabling disease in developing countries. The dosimetry for the clinical application of 153-samarium-hydroxymacroaggregates (¹⁵³Sm-HM) for radiation synovectomy (RSV) and palliative treatment for arthritic pain, as far as we know, has not been reported. The aim of this research was to estimate the radiation dose necessary for synovial ablation and pain palliation with minimum risk to the patient. ¹⁵³Sm-HM (370 MBq) was administered intra-articularly in a patient with severe knee pain and hindered motility. Regions of interest drawn on sequential, conjugated, anterior and posterior scintigraphy images were used to obtain the respective activity. The data was entered into a knee joint histological-geometric model designed with micrometric dimensions to represent the synovial cell layers. The Monte Carlo code was used to calculate the absorbed dose in each of the 12 model-cells representing the distance from the synovial liquid to the cartilage or bone. The absorbed dose in the synovial cavity was 114 Gy which is sufficient energy for RSV. The treated patient referred little pain and higher motility with no adverse reactions. ¹⁵³Sm-HM is a potentially valid radiopharmaceutical for RSV, which effectively palliates knee pain.