Fahad Marafi

Baseline patterns of bone scintigraphy in patients with established post-poliomyelitis paralysis

IntroductionPost-poliomyelitis syndrome causes variable musculoskeletal manifestations including pain, muscle weakness and fatigue. These manifestations are commonly secondary to overuse and misuse of muscles and joints and could follow a fall. Bone scan can be useful in determining the underlying cause and follow-up. The objective of this study was to describe the late scintigraphic patterns on bone scan following poliomyelitis.Materials and methodsBone scans of 8 adult patients (7 female and 1 male), aged 35 to 53xa0years, who were known to have paralytic poliomyelitis, were retrospectively studied. Six patients had unilateral while 1 had bilateral disease. All patients had three-phase bone scan and 5 had SPECT study as well. Studies were reviewed by two qualified nuclear medicine physicians and findings were recorded and analyzed.ResultsSeveral patterns were consistently identified: decreased blood pool activity in the affected lower limb of all patients; deformed ipsilateral hemi-pelvis with reduced uptake on the affected side in all patients with unilateral disease; stress changes with increased uptake in the bones of the contra-lateral lower extremity; and degenerative changes in multiple joints (shoulder, knee, hip, ankle and spine). Significant scoliosis was only noted in the patient with bilateral disease.ConclusionScintigraphic patterns on bone scan associated with the post-poliomyelitis syndrome and persistent weakness following a distant episode of poliomyelitis have been described. Awareness of these characteristic scintigraphic findings may facilitate an accurate diagnosis and lead to more appropriate patient management.

Hybrid SPECT/CT Imaging in the Management of Differentiated Thyroid Carcinoma

Differentiated thyroid cancer (DTC) has a good prognosis overall; however, lifelong follow-up is required for many cases. Radioiodine planar imaging with iodine-123 (I-123) or radioiodine-131 (I-131) remains the standard in the follow-up after initial surgery and ablation of residual thyroid tissue using I-131 therapy. Radioiodine imaging is also used in risk-stratifying and for staging of thyroid cancer, and in long-term follow-up. Unfortunately, the lack of anatomical detail on planar gamma camera imaging and superimposition of areas presenting with increased radioiodine uptake can make accurate diagnosis and localization of radioiodine-avid metastatic disease challenging, leading to false positive results and potentially to over-treatment of patients. Hybrid SPECT/CT allows precise anatomical localization and superior characterization of foci of increased tracer uptake when compared to planar imaging. This, in turn, allows the differentiation of pathological and physiological uptake, increasing the accuracy of image interpretation and ultimately improving the accuracy of DTC staging and subsequent patient management. In this review, we look at the unique and emerging role that SPECT/CT plays in the management of DTC, illustrated by examples from our own clinical practice.

Scintimammography in conjunction with ultrasonography for local breast cancer recurrence in post-mastectomy breast

The aim of this study was to compare the usefulness of (99)Tc(m)-methoxy-isobutyl-isonitrile (MIBI) scintimammography and ultrasonography, alone and in combination, for the detection of chest wall recurrence in the post-mastectomy breast. A total of 41 consecutive post-mastectomy patients (mean age 46.6 years; median age 45 years) with clinical suspicion of breast cancer recurrence were evaluated. For scintimammography all patients received a 740-900 MBq iv injection of (99)Tc(m)-MIBI; planar images were taken 5-10 min post-injection followed by supine single photon emission CT. Breast ultrasonography was performed in each patient using a 7.5 MHz transducer. Both MIBI uptake and ultrasound findings were documented using standard protocols. All patients had fine needle aspiration cytology biopsy (FNAC), core biopsy or excision biopsy for final tissue diagnosis. Of the 41 patients, 24 had true positive signs of local breast cancer recurrence upon ultrasonography, 10 were diagnosed as true negatives, a sensitivity of 86%, specificity 77%, positive predictive value (PPV) 89%, negative predictive value (NPV) 71% and accuracy 83% (p = 0.001). By comparison, scintimammography findings were found to be true positive in 25 patients and true negative in 12 patients - sensitivity 89%, specificity 92%, PPV 96%, NPV 80% and accuracy 90% (p = 0.001). Using a combination of these two modalities, the combined sensitivity was 100%, specificity 77%, PPV 90%, NPV 100% and accuracy 93%. The high NPV of the two studies in combination implies a potential use of this approach to exclude recurrent disease in patients with a low initial index of suspicion and/or when histology is indeterminate.

A proof-of-concept study analyzing the clinical utility of fluorine-18-sodium fluoride PET-CT in skeletal staging of oncology patients with end-stage renal disease on dialysis

Purpose The quality of conventional bone scintigraphy can be poor in patients with end-stage renal disease (ESRD). Fluorine-18-sodium fluoride (18F-NaF) PET-computed tomography (CT) has rapid single-pass extraction, fast clearance from the soft tissues and a better target to background ratio. The aim of the present study is to preliminarily assess the superior tracer kinetics of 18F-NaF in ESRD patients. Materials and methods A cohort comprising of 13 patients with ESRD (mean age 65.5 years; median age 68.5 years; six men and seven women) and a control group of 20 patients with normal renal function (mean age 64±7.7 years, nine men and 11 women) were analyzed qualitatively and quantitatively. Both sets of patients were referred for osseous staging of malignancy. All patients underwent a PET-CT scan after an injection of 0.06u2009mCi/kg of 18F-NaF. Results Qualitative analysis of the ESRD and the control group did not show a significant difference. The signal to noise ratio in the ESRD group (26.24±10.5) and the control group was similar (22.06±10.9), P=0.35. The extraction of radiotracer in bone was higher in ESRD with a bone to soft tissue index of 4.03±2.2 versus 2.48±1.0 in control patients (P=0.01). 18F-NaF PET-CT was positive for bone metastases in three patients and negative in 10 patients. Of the 48 total lesions, 34 (71%) were classified as benign on 18F-NaF PET-CT, whereas 10 (21%) were classified as malignant and four (8%) were classified as equivocal. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 18F-NaF PET-CT were 91, 89.5, 90, 71.4, and 89.7%, respectively (P<0.001). Conclusion The image quality of 18F-NaF PET-CT in patients with ESRD was comparable to imaging in patients with normal renal function. This can potentially translate into better diagnostic performance in patients with ESRD.

The clinical significance of incidental soft tissue uptake on whole body 18F-sodium fluoride bone PET-CT

18F-sodium fluoride (NaF) is a PET bone imaging agent and is commonly used in imaging patients with cancer; however, similar to technetium-99m medronic acid (99mTc-MDP), it can be useful in the evaluation of benign bone and joint conditions. NaF is an excellent bone-seeking agent with high bone uptake due to rapid single-pass extraction. It has negligible plasma protein binding, rapid blood, renal clearance, high bone uptake and almost all NaF delivered is retained by bone after a single pass of blood; however, uptake of NaF can be observed in non-osseous structures such as the arterial vasculature, gastrointestinal tract, genitourinary tract, and viscera. In this article, we present a spectrum of clinical cases with non-osseous NaF uptake in patients referred for cancer staging.

Initial experience with 18F-sodium fluoride (NaF) PET-CT: a viable functional biomarker in symptomatic Os acromiale

OBJECTIVEnOs acromiale (OA) is a failure of complete fusion of the acromial process. It is usually asymptomatic and discovered incidentally. OA can contribute to shoulder impingement symptoms and rotator cuff tears. 18F Sodium Fluoride (NaF) Positron Emission Tomographyxa0-CT (PET-CT) is an emerging and highly sensitive modality for oncological skeletal staging, and can show a variety of non-malignant uptake. We have analysed the relationship between 18F-NaF uptake in OA and associated symptoms of shoulder pain.nnnMETHODSnStudy population included 21 patients (mean age 60.2 ± 12xa0years; 13 females and 8 males) with OA who underwent PET-CT scan by injecting 2.22xa0MBqxa0kg-1 of 18F-NaF. The relationship between 18F-NaF uptake and OA as a cause of pain was analysed. A 3-point grading system was used to evaluate uptake of 18F-NaF.nnnRESULTSnIn total 27 OA (12 symptomatic and 15 asymptomatic) were enrolled. All symptomatic OA showed focal increase tracer uptake of Grade 2, while asymptomatic OA did not have significant activity Grade 0 (n = 11) and Grade 1 (n = 4).nnnCONCLUSIONn18F-NaF PET-CT appears to be a useful adjunct in the assessment of symptomatic OA with its particular strength being its high negative predictive value. Advances in knowledge: 18F-NaF PET-CT may be used as an ancillary tool for identifying symptomatic OAxa0 as a cause of shoulder pain in cases where other obvious causes of shoulder pain have been excluded.

Technical feasibility, radiation dosimetry and clinical use of 18 F-sodium fluoride (NaF) in evaluation of metastatic bone disease in pediatric population

PurposeThe role of 18F-fluoride (18F-NaF) PET-CT for the detection of bone metastases in adults is well established and is considered superior to conventional bone scintigraphy. However, data pertaining use of 18F-NaF PET-CT in pediatric oncology is relatively sparse. The aim of the present study is to retrospectively analyze and share a single-center experience of 18F-NaF PET-CT in pediatric population and to provide preliminary information regarding imaging technique, feasibility of this modality in young patients and radiation dosimetry measurements in pediatric oncology cases.Materials and methodsTwenty-four pediatric patients (mean age 8.0u2009±u20093.9) were included in the study for retrospective analysis. All patients were referred for primary staging or restaging for potential osseous metastatic disease and PET-CT scan was performed by injecting 2.2xa0MBq/kg (0.06xa0mCi/kg) of 18F-NaF.ResultsNine patients were imaged for primary staging and in all cases increase osteoblastic activity was seen in the primary tumor and of these, metastatic bone disease was identified in 2/9 patients. In the restaging group comprising 15/24 patients, metastatic deposits were identified in 3/15 whilst no disease was seen in the remaining 12 patients. Patients were injected a mean dose of 90.35u2009±u200922.9xa0MBq with an estimated mean effective absorbed doses of 2.98u2009±u20090.75xa0mSv for 18F-NaF and 3.37u2009±u20092.4xa0mSv for CT alone. Mean cumulative effective dose of 18F-NaF PET-CT scan was 5.11u2009±u20092.7xa0mSv.Conclusions18F-NaF PET-CT may be a feasible alternative to 99mTc MDP for radionuclide bone scintigraphy in the evaluation of pediatric bone pathology. Due to its better pharmacokinetics, there is potential that osseous staging can be achieved with relatively low doses and with a similar radiation burden as with 99mTc-MDP imaging.

Diagnostic Challenge of Staging Metastatic Bone Disease in the Morbidly Obese Patients: A Primary Study Evaluating the Usefulness of 18F-Sodium Fluoride (NaF) PET-CT

Purpose Optimizing diagnostic imaging may be challenging in obese patients. The quality of conventional bone scintigraphy can be poor in the morbidly obese due to a combination of factors including high background soft tissue activity. In comparison, sodium fluoride (18F-NaF PET-CT) has a better target-to-background ratio attributed to rapid single-pass extraction and fast clearance from the soft tissues. The aim of the present study is to assess the diagnostic efficacy of 18F-NaF PET-CT in the evaluation of bone metastases in obese cancer patients. Patients and Methods Two hundred twelve morbidly obese patients (body mass index, 45 ± 5.1 kg/m2; mean age, 57 years; range, 32–81 years) with body mass index greater than 40 kg/m2 referred for NaF PET-CT for osseous staging of malignancy were retrospectively analyzed. All patients underwent PET-CT scan by injecting 2.2 MBq/kg (0.06 mCi/kg) of 18F-NaF. Results 18F-NaF PET-CT was definitely benign in 145, possibly benign in 3, equivocal in 4, possibly malignant in 13, and definitely malignant in 47 patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 18F-NaF PET-CT were 93.1%, 96.1%, 90%, 97.3%, and 95.2%, respectively (95% confidence interval). Conclusions The results of the present study indicate that 18F-NaF PET-CT retains its high diagnostic accuracy in morbidly obese patients and, by inference, can be a preferred functional modality in these patients.