Reza Vali

18F choline PET/CT in the preoperative staging of prostate cancer in patients with intermediate or high risk of extracapsular disease: a prospective study of 130 patients.

PURPOSE To prospectively evaluate the potential value of fluorocholine (FCH) positron emission tomography (PET)/computed tomography (CT) in the preoperative staging of patients with prostate cancer who had intermediate or high risk of extracapsular disease. MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained. Overall, 132 patients with prostate cancer (mean age, 63 years +/- 7 [standard deviation]) were enrolled between October 2003 and June 2008. Two patients were subsequently excluded. In 111 patients, radical prostatectomy with extended pelvic lymph node (LN) dissection was performed. Patients were categorized into groups with intermediate (n = 47) or high (n = 83) risk of extracapsular extension on the basis of their Gleason scores and prostate specific antigen levels. Imaging was performed with an integrated PET/CT system after injection of 4.07 MBq FCH per kilogram of body weight with acquisition of dynamic images in the pelvis and whole-body images. Statistical analysis was performed on a per-patient basis. RESULTS Significant correlation was found between sections with the highest FCH uptake and sextants with maximal tumor infiltration (r = 0.68; P = .0001). Overall, 912 LNs were histopathologically examined. A per-patient analysis revealed the sensitivity, specificity, and positive and negative predictive values of FCH PET/CT in the detection of malignant LNs were 45%, 96%, 82%, and 83%, respectively. For LN metastases greater than or equal to 5 mm in diameter, sensitivity, specificity, and positive and negative predictive values were 66%, 96%, 82%, and 92%, respectively. In 13 patients, 43 bone metastases were detected. Early bone marrow infiltration was detected with only FCH PET in two patients. FCH PET/CT led to a change in therapy in 15% of all patients and 20% of high-risk patients. CONCLUSION FCH PET/CT could be useful in the evaluation of patients with prostate cancer who are at high risk for extracapsular disease, and it could be used to preoperatively exclude distant metastases. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.09090413/-/DC1.

[18F]fluorocholine PET/CT in the assessment of bone metastases in prostate cancer

Dear Sir, We read with great interest the recently published paper by Cimitan et al. [1] concerning the results of a study on the value of [F]fluorocholine PET/CT (FCH) imaging for the detection of recurrent prostate cancer with PSA relapse. The authors reported that FCH PET/CT could be useful in a selected population group (elevated PSA level >4 ng/ml and/or poorly differentiated prostate carcinoma with a Gleason score >7), to exclude distant metastases when salvage local treatment is intended. In addition, they assessed the value of delayed or dual-phase imaging, which may improve the detection of bone metastases in patients with minimal bone disease, and also claimed that they are the first to report such data [1]. Although the reported findings are potentially of great clinical interest, we think that some methodological and clinical issues require further clarification, particularly with regard to conventional imaging modalities (CIM), late phase dual imaging and the effect of hormone therapy. In this study 30 of 100 patients showed increased FCH uptake in the skeleton. The authors stated that bone metastases were confirmed by computed tomography (CT) findings from the PET/CT studies and by CIM during the clinical course in all patients except one. However, the time interval between FCH PET/CT and CIM was not clearly defined (between 1 to 6 months!); nevertheless, 6 months seems to be long. Referring to the results (Table 1), 17/30 patients were positive on CT and/or bone scintigraphy. In all other patients (13/30) with FCH-positive bone lesions, no morphological correlation with CIM is mentioned. Moreover, if these lesions were confirmed by clinical follow-up (which is not clearly noted in the manuscript), either bone marrow involvement or an early phase of osteoblastic processes without any significant morphological correlation might be a reasonable explanation; neither of these aspects is pointed out in the publication. Furthermore, a different pattern of metastatic changes in the skeleton (osteoblastic vs osteclastic) might have different FCH uptake characteristics [2], which should be considered in further studies. Moreover, only 16 out of 30 patients with bone metastases were evaluated in both early and delayed studies, which also seems to be insufficient to allow certain conclusions to be drawn. On the other hand, 23 patients (76%) with increased bone lesions were under hormone therapy. In our experience [3] in more than 300 FCH PET-CT studies, the effects of hormone therapy on FCH uptake, especially in the skeleton and with the dual imaging technique, are of great importance and require further investigation. In conclusion, we believe that increasing FCH uptake in the skeleton in delayed images is highly predictive of bone metastases [4, 5], but that it should be interpreted with caution in patients who are under hormone therapy.

Dual–Time-Point FDG PET/CT for the Evaluation of Pediatric Tumors

OBJECTIVE The utility of dual-time-point (18)F-FDG PET/CT in differentiating benign from malignant processes in pediatric patients was assessed. SUBJECTS AND METHODS Twenty-one patients (13 girls and eight boys; age range, 1-17 years) with suspected malignancy underwent dual-time-point FDG PET/CT. Scan 1 was performed at approximately 60 minutes after i.v. injection of 5.18 MBq/kg of FDG, and scan 2 was performed at 121 ± 43 minutes after the first scan. Regions of interest were overlaid onto each non-attenuated-corrected image, and semiquantitative analysis was performed using the standardized uptake value (SUV) obtained from early and delayed images. A retention index was calculated according to the following equation: [(delayed SUV - early SUV) / early SUV] × 100. Results were compared prospectively in relation to pathologic examination or other conventional radiologic imaging or clinical follow-up. A retention index of 10% or higher was chosen as a cutoff for differentiating malignant from benign entities. RESULTS For patients with malignant disease, the average SUV increased from 7.3 ± 1.2 to 10.9 ± 2.7 between the two time points, whereas the SUV changed from 4.5 ± 0.8 to 4.2 ± 1.0 for patients with benign lesions. The average retention index was 37.1% ± 10.8% for patients with malignant lesions versus -9.9% ± 7.1% for benign lesions (p < 0.01). With a cutoff value of 10% or higher for the retention index, the sensitivity and specificity of dual-time-point FDG PET/CT were 77% and 80%, respectively. CONCLUSION These data show that dual-time-point FDG PET/CT is useful in distinguishing malignant from benign processes in pediatric patients.

FDG‐PET and magnetoencephalography in presurgical workup of children with localization‐related nonlesional epilepsy

2‐[18F]Fluoro‐2‐deoxy‐d‐glucose positron emission tomography (FDG‐PET) and magnetoencephalography (MEG) may assist in identifying the epileptogenic zone in children with nonlesional localization‐related epilepsy. The aim of this study was to evaluate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FDG‐PET, MEG, FDG‐PET + MEG, and FDG‐PET/MEG in children with nonlesional localization‐related epilepsy.

Pediatric Nuclear Medicine in Acute Care

Various radiopharmaceuticals are available for imaging pediatric patients in an acute care setting. This article focuses on the common applications used on a pediatric patient in acute care. To confirm the clinical diagnosis of brain death, brain scintigraphy is considered accurate and has been favorably compared with other methods of detecting the presence or absence of cerebral blood flow. Ventilation-perfusion lung scans are easy and safe to perform with less radiation exposure than computed tomography pulmonary angiography and remain an appropriate procedure to perform on children with suspected pulmonary embolism as a first imaging test in a hemodynamically stable patient with no history of lung disease and normal chest radiograph. (99m)Tc pertechnetate scintigraphy (Meckels scan) is the best noninvasive procedure to establish the diagnosis of ectopic gastric mucosa in Meckels diverticulum. Hepatobiliary scintigraphy is the most accurate diagnostic imaging modality for acute cholecystitis. (99m)Tc-dimercaptosuccinic acid scintigraphy is the simplest, and the most reliable and sensitive method for the early diagnosis of focal or diffuse functional cortical damage. Bone scintigraphy is a sensitive and noninvasive technique for the diagnosis of bone disorders such as osteomyelitis and fracture. Of recent, positron emission tomography imaging using (18)F-NaF has been introduced as an alternative to bone scintigraphy. (18)F-fluorodeoxyglucose-positron emission tomography has the potential to replace other imaging modalities, such as the evaluation of fever of unknown origin in pediatric patients, with better sensitivity and significantly less radiation exposure than gallium scan.

The value of 18F‐FDG PET in pediatric patients with post‐transplant lymphoproliferative disorder at initial diagnosis

PTLD is a serious complication of both solid organ and BMT. This study assessed whether 18F‐FDG PET, when added to CT scan, had additional value in the initial evaluation of PTLD in pediatric patients and whether PET/CT at baseline can reliably guide biopsy. This retrospective study evaluated 34 consecutive pediatric patients (14 female), aged 3.5–17.0 yr (mean age: 9.9 yr, s.d.: 4.9 yr), who had undergone 18F‐FDG PET/CT from May 2007 to December 2014 at initial diagnosis of PTLD following heart (n = 13), lung (n = 8), kidney (n = 4), liver (n = 3), liver and bowel (n = 3), and bone marrow (n = 3) transplantation. PTLD was diagnosed histopathologically in 33 patients and was based on clinical findings, elevated EBV, and imaging and follow‐up results in one patient. On lesion‐based analysis, 18F‐FDG PET showed more lesions than conventional CT scan (168 vs. 134), but CT revealed 22 lesions negative on PET. On per patient analysis, PET detected more lesions in 13 patients, CT identified more abnormalities in seven, and both showed the same number of lesions in 14. Adding 18F‐FDG PET to CT scans upstaged the disease in seven patients (20.5%). A combination of 18F‐FDG PET and CT was also useful in guiding biopsy, being positive in 36 of 39 samples (92.3%). These findings indicated that 18F‐FDG PET and CT are complementary at initial staging of pediatric PTLD and that 18F‐FDG PET/CT scanning can guide biopsies.

Measurement of Differential Renal Function by Scintigraphy in Hydronephrotic Kidneys: Importance of Conjugate Views for Accurate Evaluation

PURPOSE Traditionally a single posterior view is used to measure differential renal function during nuclear renal scintigraphy. Nevertheless, experimental data show important variation in this measurement in the setting of significant hydronephrosis. To date, the impact of degree of hydronephrosis on the accuracy of differential renal function determination has not been addressed. We evaluated the discrepancy between function measured by anterior and posterior views, and the relationship to varying degrees of hydronephrosis. MATERIALS AND METHODS We retrospectively reviewed consecutive mercaptoacetyltriglycine renal scans from 2009 to 2011. Ultrasounds were reviewed and degree of hydronephrosis was recorded using anteroposterior pelvic diameter. Absolute percent difference in differential renal function between each view (anterior minus posterior) was calculated and correlated to anteroposterior pelvic diameter. Patients were stratified into 4 groups according to anteroposterior pelvic diameter, ie less than 10 mm, greater than 10 mm, greater than 15 mm and greater than 25 mm. RESULTS A total of 519 scans with corresponding ultrasounds were analyzed. Median patient age was 2.26 years. Kidneys with a larger anteroposterior pelvic diameter had a greater discrepancy in function on anterior and posterior views. There was a meaningful discrepancy for anteroposterior pelvic diameter greater than 10 mm (p = 0.034) and greater than 25 mm (p = 0.032). Several statistical models were used to identify a meaningful cut point of 15 mm, where the discrepancy in anterior and posterior views became significant (p = 0.001). CONCLUSIONS The use of single views during nuclear renography for grossly hydronephrotic kidneys is often inaccurate. The discrepancy in differential renal function obtained on the anterior and posterior views is adversely impacted especially as anteroposterior pelvic diameter increases beyond 15 mm. Therefore, we suggest incorporation of conjugate views for estimating differential renal function in patients with hydronephrosis.

Neuroendocrine tumor in liver with positive ACTH receptor: a case report.

A rare case of possible primary ectopic adrenocorticotropic hormone (ACTH)-producing tumor in the liver mimicking a liver hemangioma is reported. A 9-year-old boy, with Cushing syndrome, was referred for the assessment of ectopic ACTH-producing tumor. Ultrasound, CT scan, and MRI of the abdomen revealed a liver lesion suggestive of a hemangioma. 111In-octreotide scintigraphy revealed focal activity in the liver, indicative of a somatostatin-positive lesion. 99mTc-labeled RBC scintigraphy was negative for hemangioma. After surgical resection of the tumor, the cortisol level converted to a normal range indicative of a rare possible primary ACTH-producing tumor in the liver, which was confirmed by histopathology.

The Use of F-18 Choline PET in the Assessment of Bone Metastases in Prostate Cancer: Correlation with Morphological Changes on CT (vol 11, pg 446, 2009)

Erratum to: The Use of F-18 Choline PET in the Assessment of Bone Metastases in Prostate Cancer: Correlation with Morphological Changes on CT Mohsen Beheshti, Reza Vali, Peter Waldenberger, Friedrich Fitz, Michael Nader, Josef Hammer, Wolfgang Loidl, Christian Pirich, Ignac Fogelman, Werner Langsteger Nuclear Medicine & Endocrinology, PET/CT Center Linz, St. Vincent’s Hospital, Linz, Austria Radiology, St. Vincent’s Hospital, Linz, Austria Radiation Oncology, St. Vincent’s Hospital, Linz, Austria Urology, St. Vincent’s Hospital, Linz, Austria Nuclear Medicine & Endocrinology, Paracelsus Private Medical University, Salzburg, Austria Division of Imaging, King’s College, London, UK

Review: The Role of Radiolabeled DOTA-Conjugated Peptides for Imaging and Treatment of Childhood Neuroblastoma

BACKGROUND Childhood neuroblastoma is a heterogenous disease with varied clinical presentation and biology requiring different approaches to investigation and management. Metaiodobenzylguanidine (MIBG) is an essential component of metastatic staging for neuroblastoma and has been used as a treatment strategy for relapsed and refractory neuroblastoma. However, as 10% of children with neuroblastoma will have 123I-MIBG non-avid imaging and up to 60% with relapsed and refractory neuroblastoma will require further treatment with 131I-MIBG, alternative radioisotopes have been investigated for imaging and treatment. Neuroblastoma tumors express mostly somatostatin receptor- 2 (SSTR2) that can be targeted by somatostatin analogues including DOTA-conjugated peptides e.g. DOTATATE, DOTATOC. OBJECTIVES This review summarizes the rationale, utility and experience of DOTA-conjugated peptides in imaging and treatment of childhood neuroblastoma. RESULTS AND CONCLUSIONS Radiolabeled DOTA-peptides are used routinely in adults to image neuroendocrine tumors and have potential to be used to image and treat neuroblastoma. 68Ga-DOTATATE PET/CT has been shown to have better sensitivity, quicker clearance and administration times, reduced radiation exposure and limited toxicity compared to 123I-MIBG. Therapeutic studies of peptide receptor radionuclides e.g. 177Lu-DOTATATE in patients with relapsed neuroblastoma have used 68Ga- DOTATATE PET/CT to determine eligibility for therapy. Further studies would need to investigate appropriate indications, timings, scoring and clinical significance of radiolabeled DOTA-peptide conjugated PET/CT imaging in childhood neuroblastoma.