Dosimetric approach to 131I ablation therapy for the differentiated thyroid cancer.

OBJECTIVE: The aim of this study is to compare the activity amounts used in the standard activity approach with the activity amounts calculated with the dosimetric method for the ablation of post-operative differentiated thyroid cancer residual tissue. SUBJECTS AND METHODS: Seventeen patients (mean age=47.5±8.4 years) were included in the study. Time-activity curves were created by measuring iodine-131 (131I) uptake values of residual tissue at 4th, 24th, 48th and 96th hours following oral administration of 131I. In a dosimetric approach, activity amounts exposing 300Gy to residual tissue were calculated using medicalinternal radiation dose (MIRD) formulation. RESULTS: Dosimetric calculation could not be made in 3 patients because there was not enough radioactive iodine uptake (RAIU) at the neck to calculate the radioactive iodine treatment (RAIT) dose. The lowest and highest activity amounts determined by dosimetric calculations were 259MBq and 10860MBq, respectively. Dose amounts for the proposed treatment were decreased in 8 and increased in 6 patients compared to the standard activity approach. Cumulative activity (CA) and total cumulative activity (TCA) levels were found to be high in 1 patient who could not achieve adequate ablation. CONCLUSION: We recommend the dosimetric approach for ablation of residual postoperative thyroid tissue to find patients with high levels of CA and TCA levels to consider higher activity doses compared to risk stratification assessment.

PET/CT Imaging of Inflammatory Myofibroblastic Tumor of the Thigh.

A 13-year-old male patient presented with right leg pain and walking difficulty. Contrast-enhanced magnetic resonance imaging showed a softtissue lesion between muscle groups in the anterior half of the right thigh. The excisional biopsy result ended in an inflammatory myofibroblastic tumor (IMT). The 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) scan showed hypermetabolism in the multifocal soft tissue lesion and also confirmed that no other distant foci were present. A three-phase Tc-99m-methylene diphosphonate study of the region showed heterogeneously increased vascularity within the region. We described an unusual case of IMT in a pediatric patient and the importance of PET/CT scanning to delineate the lesion.

The Value of 99mTc-MIBI SPECT/CT in the Postoperative Assessment of Patients with Differentiated Thyroid Carcinoma.

BACKGROUND: The therapeutic approaches of differentiated thyroid carcinoma (DTC) are surgery, ablation therapy with the postoperative use of radioiodine-131 (131I), and thyroid-stimulating hormone (TSH) suppression therapy. After the surgical therapy, the patient should be assessed for remnants/metastases. OBJECTIVE: The purpose of this research was to investigate the role of technetium-99m-methoxyisobutylisonitrile (99mTc-MIBI) single photon emission computed tomography/computed tomography (SPECT/CT) in the postoperative management of patients with DTC. METHODS: The study comprised 22 DTC patients (13 women, 9 men; mean age 46.55 ± 13.27 y) who underwent a total thyroidectomy previously. All patients were investigated for thyroid remnants/ metastases by99mTc-MIBI SPECT/CT, posttherapy 131I whole-body scan (WBS) and ultrasound (US). Serum TSH, thyroglobulin and anti-Tg antibody levels were measured. Results of imaging modalities and laboratory measurements were compared with each other. RESULTS: 99mTc-MIBI SPECT/CT, 131I WBS and US respectively demonstrated thyroid remnants in 15 (68.18%), 22 (100%) and 14 (63.63%) of all patients and metastatic lymph nodes in 8 (100%), 6 (75%) and 6 (75%) of the 8 patients with lymph node metastases.99mTc-MIBI SPECT/CT also demonstrated lung metastases in 2 patients (9.09% of all patients). The same result was obtained with 131I WBS. CONCLUSION: The findings of this study show that 99mTc-MIBI SPECT/CT can be effective for detecting metastases in patients with DTC who underwent surgery prior to 131I therapy.

Chronic recurrent multifocal osteomyelitis: a case report.

Chronic recurrent multifocal osteomyelitis is a rare autoinflammatory, immunologic disorder. It may involve recurrent inflammatory bone pain associated with aseptic osteomyelitis. If the diagnosis is delayed, it negatively influences quality of life by leading to persistent symptoms or joint damage. Herein, we report a 16-year-old male patient who presented with left hip and right knee pain lasting for the last two months and was diagnosed as having chronic recurrent multifocal osteomyelitis as a result of further evaluation. Improvement was achieved with prednisolone and methotrexate treatment that was initiated when no response to ibuprofen treatment could be obtained. Chronic recurrent multifocal osteomyelitis must be considered in the differential diagnosis in patients presenting with joint symptoms when clinical and radiologic bone lesions are found, no microorganism growth is observed, and no response to antibiotic treatment is obtained.

Image-derived and arterial blood sampled input functions for quantitative PET imaging of the angiotensin II subtype 1 receptor in the kidney.

PURPOSE: The radioligand 11C-KR31173 has been introduced for positron emission tomography (PET) imaging of the angiotensin II subtype 1 receptor in the kidney in vivo. To study the biokinetics of 11C-KR31173 with a compartmental model, the input function is needed. Collection and analysis of arterial blood samples are the established approach to obtain the input function but they are not feasible in patients with renal diseases. The goal of this study was to develop a quantitative technique that can provide an accurate image-derived input function (ID-IF) to replace the conventional invasive arterial sampling and test the method in pigs with the goal of translation into human studies. METHODS: The experimental animals were injected with [11C]KR31173 and scanned up to 90 min with dynamic PET. Arterial blood samples were collected for the artery derived input function (AD-IF) and used as a gold standard for ID-IF. Before PET, magnetic resonance angiography of the kidneys was obtained to provide the anatomical information required for derivation of the recovery coefficients in the abdominal aorta, a requirement for partial volume correction of the ID-IF. Different image reconstruction methods, filtered back projection (FBP) and ordered subset expectation maximization (OS-EM), were investigated for the best trade-off between bias and variance of the ID-IF. The effects of kidney uptakes on the quantitative accuracy of ID-IF were also studied. Biological variables such as red blood cell binding and radioligand metabolism were also taken into consideration. A single blood sample was used for calibration in the later phase of the input function. RESULTS: In the first 2 min after injection, the OS-EM based ID-IF was found to be biased, and the bias was found to be induced by the kidney uptake. No such bias was found with the FBP based image reconstruction method. However, the OS-EM based image reconstruction was found to reduce variance in the subsequent phase of the ID-IF. The combined use of FBP and OS-EM resulted in reduced bias and noise. After performing all the necessary corrections, the areas under the curves (AUCs) of the AD-IF were close to that of the AD-IF (average AUC ratio=1±0.08) during the early phase. When applied in a two-tissue-compartmental kinetic model, the average difference between the estimated model parameters from ID-IF and AD-IF was 10% which was within the error of the estimation method. CONCLUSIONS: The bias of radioligand concentration in the aorta from the OS-EM image reconstruction is significantly affected by radioligand uptake in the adjacent kidney and cannot be neglected for quantitative evaluation. With careful calibrations and corrections, the ID-IF derived from quantitative dynamic PET images can be used as the input function of the compartmental model to quantify the renal kinetics of 11C-KR31173 in experimental animals and the authors intend to evaluate this method in future human studies.

Conjugated hyperbilirubinemia in the neonatal intensive care unit.

BACKGROUND/AIMS: To determine the underlying causes and short-term prognosis of patients with conjugated hyperbilirubinemia in a tertiary neonatal intensive care units. MATERIALS AND METHODS: We retrospectively analyzed the etiology, course, and shortterm prognosis of conjugated hyperbilirubinemia observed in newborn infants in a tertiary neonatal intensive care units. RESULTS: Of a total of 104 infants with conjugated hyperbilirubinemia (2.1%, 104/4915), 92 infants (56 full-term, 36 preterm) were enrolled in the study. Cholestatic jaundice as a sole finding on physical examination during admission was present in 15.2% infants, and conjugated hyperbilirubinemia developed within the first week of life in nearly half of the infants (51.1%). The most frequent causes of conjugated hyperbilirubinemia within the first days of life were vascular/ischemic events, inspissated bile, and inherited metabolic disorders. The majority of the infants (80%) had also concomitant clinical disorders that might possibly contributed tothe development of conjugated hyperbilirubinemia. The majority of the deaths (87%) were primarily related to serious perinatal events and genetic/inherited disorders. Bilirubin levels in the most of the survivors (87.1%) returned to normal within six months. CONCLUSIONS: Conjugated hyperbilirubinemia is not uncommon in neonatal intensive care unit. Etiology is often multifactorial and more commonly arise from non-hepatic causes. Outcome depends on the underlying causes. Early diagnosis and treatment may be critical for favorable outcome.

Modeling of the renal kinetics of the AT1 receptor specific PET radioligand [11C]KR31173.

PURPOSE: The radioligand [(11)C]KR31173 has been introduced for PET imaging of the angiotensin II subtype 1 receptor (AT1R). The purpose of the present project was to employ and validate a compartmental model for quantification of the kinetics of this radioligand in a porcine model of renal ischemia followed by reperfusion (IR). PROCEDURES: Ten domestic pigs were included in the study: five controls and five experimental animals with IR of the left kidney. To achieve IR, acute ischemia was created with a balloon inserted into the left renal artery and inflated for 60 minutes. Reperfusion was achieved by deflation and removal of the balloon. Blood chemistries, urine specific gravity and PH values, and circulating hormones of the renin angiotensin system were measured and PET imaging was performed one week after IR. Cortical time-activity curves obtained from a 90 min [(11)C]KR31173 dynamic PET study were processed with a compartmental model that included two tissue compartments connected in parallel. Radioligand binding quantified by radioligand retention (80 min value to maximum value ratio) was compared to the binding parameters derived from the compartmental model. A binding ratio was calculated as DVR = DV(S)/DV(NS), where DV(S) and DV(NS) represented the distribution volumes of specific binding and nonspecific binding. Receptor binding was also determined by autoradiography in vitro. RESULTS: Correlations between rate constants and binding parameters derived by the convolution and deconvolution curve fittings were significant (r > 0.9). Also significant was the correlation between the retention parameter derived from the tissue activity curve (Y(ret)) and the retention parameter derived from the impulse response function (f(ret)). Furthermore, significant correlations were found between these two retention parameters and DVR. Measurements with PET showed no significant changes in the radioligand binding parameters caused by IR, and these in vivo findings were confirmed by autoradiography performed in vitro. CONCLUSIONS: Correlations between various binding parameters support the concept of the parallel connectivity compartmental model. If an arterial input function cannot be obtained, simple radioligand retention may be adequate for estimation of in vivo radioligand binding.