Mucus plugging, air trapping, and bronchiectasis are important outcome measures in assessing progressive childhood cystic fibrosis lung disease.

OBJECTIVE: To determine which outcome measures could detect early progression of disease in school-age children with mild cystic fibrosis (CF) lung disease over a two-year time interval utilizing chest computed tomography (CT) scores, quantitative CT air trapping (QAT), and spirometric measurements. METHODS: Thirty-six school-age children with mild CF lung disease (median [interquartile range] age 12 [3.7] years; percent predicted forced expiratory volume in 1 second (ppFEV1 ) 99 [12.5]) were evaluated by serial spirometer-controlled chest CT scans and spirometry at baseline, 3-month, 1- and 2-years. RESULTS: No significant changes were noted at 3-month for any variable except for decreased ppFEV1 . Mucus plugging score (MPS) and QATA1andA2 increased at 1- and 2-years. The bronchiectasis score (BS), and total score (TS) were increased at 2-year. All variables tested with the exception of bronchial wall thickness score, parenchymal score (PS), and ppFEV1 , were consistent with longitudinal worsening of lung disease. Multivariate analysis revealed baseline PS, baseline TS, and 1-year changes in BS and air trapping score were predictive of 2-year changes in BS. CONCLUSIONS: MPS and QATA1-A2 were the most sensitive indicators of progressive childhood CF lung disease. The 1-year change in the bronchiectasis score had the most positive predictive power for 2-year change in bronchiectasis.

The strong but nonspecific relationship between 18F-FDG uptake in the lower-extremity veins and venous thromboembolism.

Venous thromboembolism (VTE) can present as deep vein thrombosis (DVT) and/or acute pulmonary embolism (PE). In fluorine-18 fluorodeoxyglucose (18F-FDG) PET/CT, 18F-FDG activity along the deep veins of the lower extremities (LE) is often observed and, unless it is associated with focal intense activity, is not considered abnormal. However, anecdotally it has been associated with the placement of an inferior vena cava filter. In this short paper we intend to investigate this association. We found 10 patients who were investigated in the vascular laboratory by means of either LE or upper-extremity duplex or a chest computed tomography with PE protocol, or who had undergone the placement of an inferior vena cava filter between 27 April 2010 and 7 January 2013 and who had also undergone one or more 18F-FDG-PET scan(s) that included the LE. Seventeen patients without venous 18F-FDG uptake were added as controls. 18F-FDG uptake visualized in the LE was scored as the number of positive LE veins and the extent of the radiotracer uptake. The time intervals between the VTE event and the 18F-FDG-PET scan(s) were recorded. The time intervals between the most remote and the closest 18F-FDG-PET before a VTE event averaged 79 ± 101 and 49 ± 82 days, respectively, and the closest and the most remote 18F-FDG-PET after the VTE event averaged 58 ± 50 and 122 ± 124 days. The extent of uptake in the LE veins averaged 7 ± 2 for the patients with an acute DVT on LE duplex and 5 ± 3 for those with negative or chronic DVT on LE duplex (P=nonsignificant). Two patients (n=3 and 10) were negative for VTE events and had an extent of 0. The number of positive events correlated slightly with the extent of venous uptake (r=0.69). The 17 control patients without venous uptake on 18F-FDG-PET had no history of VTE. There was an association between LE venous uptake of 18F-FDG and risk for VTE. The association was not related to the location of the VTE, nor to the timing of the VTE.

Fusion dual-tracer SPECT-based hepatic dosimetry predicts outcome after radioembolization for a wide range of tumour cell types.

PURPOSE: Fusion dual-tracer SPECT imaging enables physiological rather than morphological voxel-based partitioning and dosimetry for (90)Y hepatic radioembolization (RE). We evaluated its prognostic value in a large heterogeneous cohort of patients with extensive hepatic malignancy. METHODS: A total of 122 patients with primary or secondary liver malignancy (18 different cell types) underwent SPECT imaging after intraarterial injection of (99m)Tc macroaggregated albumin (TcMAA) as a simulation of subsequent (90)Y microsphere distribution, followed by administration of an excess of intravenous (99m)Tc-labelled sulphur colloid (TcSC) as a biomarker for functional liver, and a second SPECT scan. TcMAA distribution was used to estimate (90)Y radiation absorbed dose in tumour (D T) and in functional liver. Laboratory and clinical follow-up were recorded for 12 weeks after RE, and radiographic responses according to (m)RECIST were evaluated at 3 and 6 months. Dose-response relationships were determined for efficacy and toxicity. RESULTS: Patients were treated with a median of 1.73 GBq activity of resin microspheres (98 patients) or glass microspheres (24 patients), in a whole-liver approach (97 patients) or a lobar approach (25 patients). The objective response rate was 41% at 3 months and 48% at 6 months. Response was correlated with D T (P < 0.01). Median overall survival was 10.1 months (95% confidence interval 7.4 - 12.8 months). Responders lived for 36.0 months compared to 8.7 months for nonresponders (P < 0.01). Stratified for tumour cell type, D T was independently associated with survival (P < 0.01). Absorbed dose in functional liver was correlated with toxicity grade change (P < 0.05) and RE-induced liver disease (P < 0.05). CONCLUSION: Fusion dual-tracer SPECT imaging offers a physiology-based functional imaging tool to predict efficacy and toxicity of RE. This technique can be refined to define dosing thresholds for specific tumour types and treatments, but appears generally predictive even in a heterogeneous cohort.

An evaluation of the predictive value of mid-treatment 18F-FDG-PET/CT scans in pediatric lymphomas and undefined criteria of abnormality in quantitative analysis.

Our purpose was to evaluate quantitative mid-treatment fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT scans in predicting the quantitative result of the end of treatment 18F-FDG PET/CT scan. With approval of Emory's Institutional Review Board, data were extracted from 273 existing 18F-FDG PET/CT scans of 143 pediatric patients performed for evaluation of lymphoma. The inclusion criteria were the availability of an initial staging scan (D0) and a mid-treatment scan after 1 to 3 cycles of chemotherapy (D1) and a post-treatment scan (D2). Absolute and relative changed of D1 compared to D0 were measured and their values in predicting D3 values were determined. Analysis was performed on a lesion basis (N=78) in 18 patients with an average of 4.3 lesions per patients. Results showed that the predictive value depended on the value selected as significant for the predictors (D1 SUV and D1 %SUV), and on the limit between negative and positive selected for the predicted value D2 SUV. If the maximum SUV<2.0 in D2 was the limit for negative, the negative predictive value if D1<4 was 0.84%. If positive was defined as D2>3.0, the positive predictive value of D1>4 was 100%. In that way outcome was predictable with absolute certainty in as many as 71% of the lesions with a single limit for D1 and D2. In conclusion, in this limited retrospective study the positive predictive value of the mid-treatment scan, was high for the post-treatment result for patient and lesion response seen on D2.

Prognostic utility of 90Y radioembolization dosimetry based on fusion 99mTc-macroaggregated albumin-99mTc-sulfur colloid SPECT.

UNLABELLED: Planning hepatic (90)Y radioembolization activity requires balancing toxicity with efficacy. We developed a dual-tracer SPECT fusion imaging protocol that merges data on radioactivity distribution with physiologic liver mapping. METHODS: Twenty-five patients with colorectal carcinoma and bilobar liver metastases received whole-liver radioembolization with resin microspheres prescribed as per convention (mean administered activity, 1.69 GBq). As part of standard treatment planning, all patients underwent SPECT imaging after intraarterial injection of 37 MBq of (99m)Tc-macroaggregated albumin ((99m)Tc-MAA) to simulate subsequent (90)Y distribution. Immediately afterward, patients received 185 MBq of labeled sulfur colloid ((99m)Tc-SC) intravenously as a biomarker for normal hepatic reticuloendothelial function and SPECT was repeated. The SPECT images were coregistered and fused. A region-based method was used to predict the (90)Y radiation absorbed dose to functional liver tissue (DFL) by calculation of (99m)Tc-MAA activity in regions with (99m)Tc-SC uptake. Similarly, the absorbed dose to tumor (DT) was predicted by calculation of (99m)Tc-MAA activity in voxels without (99m)Tc-SC uptake. Laboratory data and radiographic response were measured for 3 mo, and the survival of patients was recorded. SPECT-based DT and DFL were correlated with parameters of toxicity and efficacy. RESULTS: Toxicity, as measured by increase in serum liver enzymes, correlated significantly with SPECT-based calculation of DFL at all time points (P < 0.05) (mean DFL, 27.9 Gy). Broad biochemical toxicity (>50% increase in all liver enzymes) occurred at a DFL of 24.5 Gy and above. In addition, in uni- and multivariate analysis, SPECT-based calculation of DT (mean DT, 44.2 Gy) correlated with radiographic response (P < 0.001), decrease in serum carcinoembryonic antigen (P < 0.05), and overall survival (P < 0.01). The cutoff value of DT for prediction of 1-y survival was 55 Gy (area under the receiver-operating-characteristic curve = 0.86; P < 0.01). Patients who received a DT of more than 55 Gy had a median survival of 32.8 mo, compared with 7.2 mo in patients who received less (P < 0.05). CONCLUSION: Dual-tracer (99m)Tc-MAA-(99m)Tc-SC fusion SPECT offers a physiology-based imaging tool with significant prognostic power that may lead to improved personalized activity planning.

Safety of repeated yttrium-90 radioembolization.

PURPOSE: Repeated radioembolization (RE) treatments carry theoretically higher risk of radiation-induced hepatic injury because of the liver's cumulative memory of previous exposure. We performed a retrospective safety analysis on patients who underwent repeated RE. METHODS: From 2004 to 2011, a total of 247 patients were treated by RE. Eight patients (5 men, 3 women, age range 51-71 years) underwent repeated treatment of a targeted territory, all with resin microspheres (SIR-Spheres; Sirtex, Lane Cove, Australia). Adverse events were graded during a standardized follow-up. In addition, the correlation between the occurrence of RE-induced liver disease (REILD) and multiple variables was investigated in univariate and multivariate analyses in all 247 patients who received RE. RESULTS: Two patients died shortly after the second treatment (at 84 and 107 days) with signs and symptoms of REILD. Both patients underwent whole liver treatment twice (cumulative doses 3.08 and 2.66 GBq). The other 6 patients demonstrated only minor toxicities after receiving cumulative doses ranging from 2.41 to 3.88 GBq. All patients experienced objective tumor responses. In the whole population, multifactorial analysis identified three risk factors associated with REILD: repeated RE (p = 0.036), baseline serum total bilirubin (p = 0.048), and baseline serum aspartate aminotransferase (p = 0.043). Repeated RE proved to be the only independent risk factor for REILD in multivariate analysis (odds ratio 9.6; p = 0.002). Additionally, the administered activity per target volume (in GBq/L) was found to be an independent risk factor for REILD, but only in whole liver treatments (p = 0.033). CONCLUSION: The risk of REILD appears to be elevated for repeated RE. Objective tumor responses were observed, but establishment of safety limits will require improvement in dosimetric measurement and prediction.

Brain uptake of Tc99m-HMPAO correlates with clinical response to the novel redox modulating agent EPI-743 in patients with mitochondrial disease.

While decreased ATP production and redox imbalance are central to mitochondrial disease pathogenesis, efforts to develop effective treatments have been hampered by the lack of imaging markers of oxidative stress. In this study we wished to determine if Tc99m-HMPAO, a SPECT imaging marker of cerebral blood flow and glutathione/protein thiol content, could be used to monitor the effect(s) of EPI-743, an oral redox modulating, para-benzoquinone based therapeutic for mitochondrial disease. We hypothesized that treatment changes in HMPAO uptake would be inversely proportional to changes in oxidative stress within the brain and directly correlate to clinical response to EPI-743 therapy. Twenty-two patients with mitochondrial disease were treated with EPI-743. Each underwent baseline and 3-month Tc99m-HMPAO SPECT scanning along with clinical/neurologic evaluations. Diseases treated were: Leigh syndrome (n=7), polymerase γ deficiency (n=5), MELAS (n=5), Friedreich ataxia (n=2), Kearns-Sayre syndrome, Pearson syndrome, and mtDNA depletion syndrome. Neuro-anatomic uptake analyses of HMPAO were performed with NeuroGam™ (Segami Corp.) statistical software and clinical response was assessed by the Newcastle Paediatric Mitochondrial Disease Scale or Newcastle Mitochondrial Disease Adult Scale depending on patient age. For all 22 patients there was a significant linear correlation between the change in cerebellar uptake of HMPAO and the improvement in Newcastle score (r=0.623, **p=0.00161). The MELAS subgroup showed a significant relationship of whole brain uptake (n=5, r=0.917, *p=0.028) to improvement in Newcastle score. We conclude that Tc99m-HMPAO SPECT scanning has promise as a general marker of the oxidative state of the brain and its response to redox modulating therapies. Further studies will be needed to confirm these findings in a more homogenous study population.

Positron emission tomography of 64Cu-DOTA-Rituximab in a transgenic mouse model expressing human CD20 for clinical translation to image NHL.

PURPOSE: This study aims to evaluate (64)Cu-DOTA-rituximab (PETRIT) in a preclinical transgenic mouse model expressing human CD20 for potential clinical translation. PROCEDURES: (64)Cu was chelated to DOTA-rituximab. Multiple radiolabeling, quality assurance, and imaging experiments were performed. The human CD20 antigen was expressed in B cells of transgenic mice (CD20TM). The mice groups studied were: (a) control (nude mice, n = 3) that received 7.4 MBq/dose, (b) with pre-dose (CD20TM, n = 6) received 2 mg/kg pre-dose of cold rituximab prior to PETRIT of 7.4 MBq/dose, and (c) without pre-dose (CD20TM, n = 6) PETRIT alone received 7.4 MBq/dose. Small animal PET was used to image mice at various time points (0, 1, 2, 4, 24, 48, and 72 h). The OLINDA/EXM software was used to determine the human equivalent dose for individual organs. RESULTS: PETRIT was obtained with a specific activity of 545 ± 38.91 MBq/nmole, radiochemical purity >95%, and immunoreactivity >75%. At 24 h, spleenic uptake of PETRIT%ID/g (mean ± STD) with and without pre-dose was 1.76 ± 0.43% and 16.5 ± 0.45%, respectively (P value = 0.01). Liver uptake with and without pre-dose was 0.41 ± 0.51% and 0.52 ± 0.17% (P value = 0.86), respectively. The human equivalents of highest dose organs with and without pre-dose are osteogenic cells at 30.8 ± 0.4 µSv/MBq and the spleen at 99 ± 4 µSv/MBq, respectively. CONCLUSIONS: PET imaging with PETRIT in huCD20 transgenic mice provided human dosimetry data for eventual applications in non-Hodgkins lymphoma patients.

Pilot pharmacokinetic and dosimetric studies of (18)F-FPPRGD2: a PET radiopharmaceutical agent for imaging α(v)ß(3) integrin levels.

PURPOSE: To assess the safety, biodistribution, and dosimetric properties of the positron emission tomography (PET) radiopharmaceutical agent fluorine 18 ((18)F) FPPRGD2 (2-fluoropropionyl labeled PEGylated dimeric RGD peptide [PEG3-E{c(RGDyk)}2]), which is based on the dimeric arginine-glycine-aspartic acid (RGD) peptide sequence and targets α(v)ß(3) integrin, in the first volunteers imaged with this tracer. MATERIALS AND METHODS: The protocol was approved by the institutional review board, and written informed consent was obtained from all participants. Five healthy volunteers underwent whole-body combined PET-computed tomography 0.5, 1.0, 2.0, and 3.0 hours after tracer injection (mean dose, 9.5 mCi ± 3.4 [standard deviation] [351.5 MBq ± 125.8]; mean specific radioactivity, 1200 mCi/mmol ± 714 [44.4 GBq/mmol ± 26.4]). During this time, standard vital signs, electrocardiographic (ECG) readings, and blood sample values (for chemistry, hematologic, and liver function tests) were checked at regular intervals and 1 and 7 days after the injection. These data were used to evaluate tracer biodistribution and dosimetric properties, time-activity curves, and the stability of laboratory values. Significant changes in vital signs and laboratory values were evaluated by using a combination of population-averaged generalized estimating equation regression and exact paired Wilcoxon tests. RESULTS: The administration of (18)F-FPPRGD2 was well tolerated, with no marked effects on vital signs, ECG readings, or laboratory values. The tracer showed the same pattern of biodistribution in all volunteers: primary clearance through the kidneys (0.360 rem/mCi ± 0.185 [0.098 mSv/MBq ± 0.050]) and bladder (0.862 rem/mCi ± 0.436 [0.233 mSv/MBq ± 0.118], voiding model) and uptake in the spleen (0.250 rem/mCi ± 0.168 [0.068 mSv/MBq ± 0.046]) and large intestine (0.529 rem/mCi ± 0.236 [0.143 mSv/MBq ± 0.064]). The mean effective dose of (18)F-FPPRGD2 was 0.1462 rem/mCi ± 0.0669 (0.0396 mSv/MBq ± 0.0181). With an injected dose of 10 mCi (370 MBq) and a 1-hour voiding interval, a patient would be exposed to an effective radiation dose of 1.5 rem (15 mSv). Above the diaphragm, there was minimal uptake in the brain ventricles, salivary glands, and thyroid gland. Time-activity curves showed rapid clearance from the vasculature, with a mean 26% ± 17 of the tracer remaining in the circulation at 30 minutes and most of the activity occurring in the plasma relative to cells (mean whole blood-plasma ratio, 0.799 ± 0.096). CONCLUSION: (18)F-FPPRGD2 has desirable pharmacokinetic and biodistribution properties. The primary application is likely to be PET evaluation of oncologic patients-especially those with brain, breast, or lung cancer. Specific indications may include tumor staging, identifying patients who would benefit from antiangiogenesis therapy, and separating treatment responders from nonresponders early.

131I-Tositumomab (Bexxar) vs. 90Y-Ibritumomab (Zevalin) therapy of low-grade refractory/relapsed non-Hodgkin lymphoma.

INTRODUCTION: The American Cancer Society estimated 66,120 new cases of non-Hodgkin lymphoma (NHL) in the USA in 2008. Radioimmunotherapy has been shown in clinical trials to be an effective treatment for refractory/relapsed NHL. The available agents are Bexxar, a (131)I radiolabeled murine monoclonal antibody, and Zevalin, a (90)Y radiolabeled murine antibody. Both target CD20 receptors present on the surface of lymphocytes. We present our clinical experience with Bexxar and Zevalin in the management of low-grade refractory or relapsed NHL. METHODS: This is a retrospective study (Jan 2000-Jul 2006) of 67 patients with NHL, who were treated with Bexxar (31 patients, group A) or Zevalin (36 patients, group B) for refractory/relapsed disease. Group A included 16 men and 15 women, 35-81 years old (average, 59.3 +/- 13.4). Group B included 27 men and nine women, 36-85 years old (average, 55.4 +/- 13.8). Therapeutic doses ranged 40-138 mCi (average, 78.1 +/- 28.2) for Bexxar and 17-34 mCi (average, 28.8 +/- 4.37) for Zevalin. RESULTS: Objective responses were induced in 22 of the 31 patients (70.9%) in group A and 28 of the 36 patients (77.8%) in group B. Complete response was noted in 11 patients (35.5%), partial response in seven patients (22.6%), and mixed response in four patients (12.9%) in group A. There were five patients (16.1%) with stable disease and four patients (12.9%) with disease progression in the same group. Complete response was noted in 15 patients (41.7%), partial response in nine patients (25%), and mixed response in four patients (11.1%) in group B. There were four patients (11.1%) with stable disease and another four patients (11.1%) with disease progression in the same group. The average decreases at posttherapy nadir were 36.9% +/- 0.33 (group A) and 52.6% +/- 0.32 (group B) for platelets, 27.8% +/- 0.27 (group A) and 34.2% +/- 0.38 (group B) for leukocytes, and 4.9% +/- 0.15 (group A) and 7.6% +/- 0.11 (group B) for hemoglobin. Grades 3 and 4 hematological toxicity occurred in 14 patients (45.2%) treated with Bexxar and 22 patients (61.1%) treated with Zevalin, but was reversible. CONCLUSION: Our study suggests that clinical practice of Bexxar and Zevalin radioimmunotherapy is an effective and safe adjunctive treatment for patients with NHL refractory/relapsed to conventional treatment. However, due to the small number of subjects, it was not possible to determine whether differences in the outcomes or toxicities from the two agents were statistically significant.

Incorporating cone-beam CT into the treatment planning for yttrium-90 radioembolization.

PURPOSE: To prepare for yttrium-90 ((90)Y) microsphere radioembolization therapy, digital subtraction angiography (DSA) and technetium- 99m-labeled macroaggregated albumin ((99m)Tc MAA) scintigraphy are used for treatment planning and detection of potential nontarget embolization. The present study was performed to determine if cone-beam computed tomography (CBCT) affects treatment planning as an adjunct to these conventional imaging modalities. MATERIALS AND METHODS: From March 2007 to August 2008, 42 consecutive patients (21 men, 21 women; mean age, 59 years; range, 21-75 y) who underwent radioembolization were evaluated by CBCT in addition to DSA and (99m)Tc MAA scintigraphy during treatment planning, and their records were retrospectively reviewed. The contrast-enhanced territories shown by CBCT with selective intraarterial contrast agent administration were used to predict intrahepatic and possible extrahepatic distribution of microspheres. RESULTS: In 22 of 42 cases (52%), extrahepatic enhancement or incomplete tumor perfusion seen on CBCT affected the treatment plan. In 14 patients (33%), the findings were evident exclusively on CBCT and not detected by DSA. When comparing CBCT versus (99m)Tc MAA scintigraphy, CBCT showed eight cases of extrahepatic enhancement (19%) that were not evident on (99m)Tc MAA imaging. CBCT findings directed the additional embolization of vessels or repositioning of the catheter for better contrast agent and microsphere distribution. One case of gastric ulcer from nontarget embolization caused by reader error was observed. CONCLUSIONS: CBCT can provide additional information about tumor and tissue perfusion not currently detectable by DSA or (99m)Tc MAA imaging, which should optimize (90)Y microsphere delivery and reduce nontarget embolization.

Quantitative analysis of longitudinal response to aerosolized granulocyte-macrophage colony-stimulating factor in two adolescents with autoimmune pulmonary alveolar proteinosis.

BACKGROUND: Autoimmune pulmonary alveolar proteinosis (APAP) is characterized by autoantibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF) in blood and tissues, resulting in alveolar surfactant protein accumulation. Patients with APAP present with ground-glass opacities (GGOs) and interlobular septal thickening on thin-slice chest CT scans. Aerosolized GM-CSF therapy (aeroGM-SCF) has qualitatively improved the clinical condition of patients with APAP. This report details quantitative chest CT responses to aeroGM-CSF. METHODS: Two adolescent patients (aged 16 and 19 years) with APAP were treated with aeroGM-CSF. Clinical parameters, including pulmonary function tests and chest CT scans, were obtained before and after aeroGM-CSF therapy. To evaluate the effect of the therapy, serial chest CT scans were analyzed using a novel approach permitting quantitative assessment of improvement in GGOs, lung weight, and gas volume. RESULTS: In association with GM-CSF treatment, nutritional status and pulmonary function improved. Quantitative analysis of the CT scans demonstrated reduction in GGOs and lung weight, concomitant with an increase in airspace volume and lung inflation. The findings were consistent with a qualitative reduction in GGOs on chest CT imaging. CONCLUSIONS: Quantitative analysis of CT holds promise as a sensitive diagnostic tool permitting longitudinal and objective analysis of the therapeutic response to aeroGM-CSF in patients with APAP.

Novel strategy for a cocktail 18F-fluoride and 18F-FDG PET/CT scan for evaluation of malignancy: results of the pilot-phase study.

UNLABELLED: (18)F-FDG PET/CT is used for detecting cancer and monitoring cancer response to therapy. However, because of the variable rates of glucose metabolism, not all cancers are identified reliably. Sodium (18)F was previously used for bone imaging and can be used as a PET/CT skeletal tracer. The combined administration of (18)F and (18)F-FDG in a single PET/CT study for cancer detection has not been reported to date. METHODS: This is a prospective pilot study (November 2007-November 2008) of 14 patients with proven malignancy (6 sarcoma, 3 prostate cancer, 2 breast cancer, 1 colon cancer, 1 lung cancer, and 1 malignant paraganglioma) who underwent separate (18)F PET/CT and (18)F-FDG PET/CT and combined (18)F/(18)F-FDG PET/CT scans for the evaluation of malignancy (a total of 3 scans each). There were 11 men and 3 women (age range, 19-75 y; average, 50.4 y). RESULTS: Interpretation of the combined (18)F/(18)F-FDG PET/CT scans compared favorably with that of the (18)F-FDG PET/CT (no lesions missed) and the (18)F PET/CT scans (only 1 skull lesion seen on an (18)F PET/CT scan was missed on the corresponding combined scan). Through image processing, the combined (18)F/(18)F-FDG scan yielded results for bone radiotracer uptake comparable to those of the (18)F PET/CT scan performed separately. CONCLUSION: Our pilot-phase prospective trial demonstrates that the combined (18)F/(18)F-FDG administration followed by a single PET/CT scan is feasible for cancer detection. This combined method opens the possibility for improved patient care and reduction in health care costs.

Sampling density for the quantitative evaluation of air trapping.

BACKGROUND: Concerns have been expressed recently about the radiation burden on patient populations, especially children, undergoing serial radiological testing. To reduce the dose one can change the CT acquisition settings or decrease the sampling density. OBJECTIVE: In this study we determined the minimum desirable sampling density to ascertain the degree of air trapping in children with cystic fibrosis. MATERIALS AND METHODS: Ten children with cystic fibrosis in stable condition underwent a volumetric spiral CT scan. The degree of air trapping was determined by an automated algorithm for all slices in the volume, and then for 1/2, 1/4, to 1/128 of all slices, or a sampling density ranging from 100% to 1% of the total volume. The variation around the true value derived from 100% sampling was determined for all other sampling densities. RESULTS: The precision of the measurement remained stable down to a 10% sampling density, but decreased markedly below 3.4%. CONCLUSION: For a disease marker with the regional variability of air trapping in cystic fibrosis, regardless of observer variability, a sampling density below 10% and even more so, below 3.4%, apparently decreases the precision of the evaluation.

(18)F-FDG-PET/CT evaluation of response to treatment in lymphoma: when is the optimal time for the first re-evaluation scan?

Assessing the response to treatment as soon after treatment initiation is one of the key reasons for imaging lymphoma patients. The optimal time after initiating treatment for assessing response to treatment has yet to be determined. Therefore, we were prompted to review our experience with serial (18)F-FDG PET/CT in patients undergoing treatment for Hodgkin's disease (HD) and non Hodgkin's lymphoma (NHL). This is a retrospective study (Feb 2003 - Oct 2004) of 20 patients, 11 men and 9 women, with age range of 7-75 years with diagnosis of HD (10) and NHL (10), who had PET/CT at our institution prior, during and at the completion of therapy. Restaging PET/CT was done after 2 cycles of chemotherapy in 10 patients (group A) and after 4 cycles of chemotherapy in 10 pts (group B). A total of 60 scans were reviewed. The DeltaSUV from baseline to first PET/CT was on average 67.6% in group A and 75.1% in group B. This had no statistical significance (P value: 0.31). The DeltaSUV from baseline to post-therapy PET/CT was on average 72.9% in group A and 79.8% in group B. This difference also had no statistical significance (P value: 0.24). The correlation coefficient was 0.98 in group A and 0.80 in group B. Results of PET/CT after 2 cycles of chemotherapy did not statistically differ from the results of PET/CT after 4 cycles of chemotherapy. These results need to be confirmed in larger, prospective, randomized trials.

90Y-ibritumomab therapy in refractory non-Hodgkin's lymphoma: observations from 111In-ibritumomab pretreatment imaging.

UNLABELLED: Radioimmunotherapy is an effective treatment for non-Hodgkin's lymphoma (NHL). 90Y-ibritumomab is an antibody targeting CD20 receptors on the surface of lymphocytes. We present observations from our clinical experience with 90Y-ibritumomab in the management of NHL. METHODS: This was a retrospective study of 28 NHL patients treated with 90Y-ibritumomab. There were 21 men and 7 women, 36-85 y old. A diagnostic dose of 111In-ibritumomab was administered on day 0, and imaging followed immediately and at 24, 48, and 72 h. The doses of 90Y-ibritumomab ranged from 629 to 1,258 MBq (17-34 mCi). Outcomes were compared with the findings of the 111In-ibritumomab scans. RESULTS: 90Y-ibritumomab induced objective responses in 22 of 28 patients. A complete response was noted in 9 patients, a partial response in 9 patients, and a mixed response in 4 patients. Three patients had stable disease, and 3 patients had disease progression. 111In-ibritumomab findings were positive in 19 patients and negative in 9 patients. A complete response was noted in 2 of 19 patients with positive findings and 7 of 9 with negative findings. A partial response was seen in 7 of 19 patients with positive findings and 1 of 9 with negative findings. Disease progression was observed in 3 of 19 patients with positive findings and 0 of 9 with negative findings. The remaining patients had a mixed response or no changes. CONCLUSION: A higher rate of complete response after 90Y-ibritumomab treatment was seen in patients with negative 111In-ibritumomab findings, whereas a higher rate of disease progression despite therapy was noted in patients with positive 111In-ibritumomab findings. This observation suggests that patients with bulky disease may require more aggressive management.

Perspectives of molecular imaging and radioimmunotherapy in lymphoma.

Successful treatment of Hodgkin lymphomas and non-Hodgkin lymphomas depends on accurate staging and prognostic estimations, as well as evaluation of response to therapy as early after initiation as possible. We focus on several aspects of molecular imaging and therapy that affect the management of patients who have lymphoma. First, we review prior use of gallium-67 citrate for evaluation of lymphoma patients, mainly from a historical perspective, since it was the mainstream lymphoma functional imaging tracer for decades. Next, we review current clinical uses of 18F Fluoro-2-Deoxyglucose (18F FDG) PET and PET/CT for evaluation of lymphoma patients and use of radioimmunotherapy in lymphoma. Finally, we discuss advances in molecular imaging that may herald the next generation of PET radiotracers after 18F FDG.

Monitoring the protective effects of minocycline treatment with radiolabeled annexin V in an experimental model of focal cerebral ischemia.

UNLABELLED: Minocycline is an antibiotic now recognized to have antiapoptotic and antiinflammatory properties. Because of these properties, minocycline may be of benefit in reducing neuronal apoptosis from ischemia and subsequent postischemic inflammation if administered soon after a stroke. We now explore the feasibility of using (99m)Tc-annexin V, an in vivo marker of apoptosis, with SPECT to monitor the antiapoptotic effects of minocycline therapy. METHODS: CB6/F1 adult male mice underwent unilateral distal middle cerebral artery occlusion (dMCA) occlusion and were imaged and sacrificed at 1, 3, 7, or 30 d after injury. Animals were given minocycline (or vehicle) 30 min and 12 h after dMCA occlusion and then given 22.5 mg/kg twice daily for up to 7 d. Before imaging, behavioral tests were performed to evaluate the neurologic function. After imaging, brains were collected for histology and assessed for the degree of apoptosis and microglial activation. RESULTS: (99m)Tc-Annexin V uptake in injured hemispheres was significantly decreased 2- to 3-fold by minocycline at all time points. Minocyline reduced infarct size as seen histologically and improved behavioral indices as late as 30 d. Infarct volume as seen histologically correlated with radiolabeled annexin V uptake seen by SPECT. In situ fluorescent microscopy demonstrated that annexin V bound primarily to neurons at 1 and 3 d, with a shift toward microglia by 7 and 30 d. CONCLUSION: We found that minocycline significantly reduces neuronal apoptosis and infarct size and improves neurologic outcome in mice after acute focal cortical ischemia.

A critical discussion of computer analysis in medical imaging.

Medical imaging has increasingly provided surrogate endpoints in therapeutic trials. This use assumes that the interpretation of the images can be unbiased and reproducible and that the image attributes included in the interpretation are relevant to the mechanism of the trial. The principal motivation for computer analysis is to evaluate an attribute of the image as a metric in an algorithmic manner, independent of observer bias or variability. The metric is expected to reflect change in rough proportion with at least one aspect of the degree of disease or the effectiveness of the therapeutic intervention. If either condition is satisfied, the measure is quantitative. Visual interpretation explicitly or implicitly tends to be based on multiple image attributes. Explicit combination of multiple attributes yields composite scores. To evaluate the risk or probability of disease, they are useful. But the components of the scores can be combined only if they are mathematically isomorphic. For the evaluation of interventions, they are less useful because the effect on one component may be obscured by the lack of effect on other components. This article reviews quantification of air trapping in cystic fibrosis and quantification in general. Validation of any computer analysis can rely on agreement with visual interpreters (on average), they can be derived from first principles, or by agreement with an alternative method that measures the pathophysiological mechanism directly (xenon washout for air trapping). However, in the context of trials, the validation may come from a superior ability to detect objective change and to discriminate between affected and unaffected individuals.