Comparison of [18F]FDG-PET and L-3[123I]-iodo-alpha-methyl tyrosine (I-123 IMT)-SPECT in primary lung cancer.

OBJECTIVE: The aim of this study was to evaluate L-3[123I]-iodo-alpha-methyl tyrosine (IMT)-SPECT and FDG-PET in pulmonary lesions suspected to be lung cancer. METHODS: Whole body PET (measured transmission corrected emission scans) was performed 45 minutes after i.v. injection of 222-370 MBq (6-10 mCi) 18F-FDG on a Siemens PET scanner (ECAT EXACT 47) including 5-6 bed positions. 123I-IMT-SPECT (chest) was performed after injection of 370 MBq (10 mCi) with a dual head camera (Picker Prism 2000) and commercially available reconstruction algorithms. Ten patients (6 male and 4 female) with suspected lung cancer were investigated. The results were compared to histological findings after surgery or bronchoscopic biopsies and CT. RESULTS: 123I-IMT-SPECT and FDG-PET were able to detect all 9 cases of lung cancer (1-8 cm in diameter). One case was true negative. Both imaging methods were true positive with respect to mediastinal lymph node metastases in one patient. The tumor/background ratio was higher with PET (8.20 vs. 2.84). CONCLUSION: Despite the limited number of patients it may be concluded that IMT-SPECT as well as FDG-PET are suited to correctly diagnose lung cancer. Nevertheless, FDG-PET, if available, seems to be better suited because of the higher tumor/background ratio and better resolution.

Case report: regional cerebral hypoperfusion induced by ventricular tachycardia - short-term hippocampal hypoperfusion and its potential relationship to selective neuronal damage.

BACKGROUND: Focussing on regional cerebral hypoperfusion during hemodynamically stable, but borderline hypotensive, sustained ventricular tachycardia (VT) experimental studies show (1) a reduction of cerebral blood flow (CBF) during tachyarrhythmias in contrast to the concept of CBF autoregulation, (2) a mediation of hypoperfusion by neuronal and humoral mechanisms, and (3) an involvment of microcirculation due to an ischemic stress response of the cerebral tissue. The clinical relevance of these observations remains still unclear. CASE REPORTS: Two patients with coronary artery disease, left ventricular dysfunction and sustained monomorphic VT underwent electrophysiological study. VT was induced and the tracer (99m)Tc-HMPAO was injected after 3 minutes of ongoing VT. Regional CBF during this life threatening arrhythmia was determined with brain SPECT. A scanning protocol was performed after termination of VT. The measurements were repeated at baseline during normofrequent sinus rhythm (SR) one week later. CBF during SR was significantly reduced in the temporal lobe in comparison to the conditions during stable VT, particularly in the left hippocampus. CONCLUSION: The reduction of hippocampal CBF due to cerebrovascular vasoconstriction and neuronal reflex mechanism previously observed in experiments during stable, sustained VT can be confirmed in a clinical scenario by high resolution (99m)Tc-HMPAO brain SPECT. This supports the hypothesis that repetitive stable VT can play a role in the pathophysiology of cerebrovascular insufficiency. Further clinical studies are needed to analyze the impact of tachyarrhythmias on cognitive and mnemic function.

Painful multifocal arthritis: therapy with rhenium 186 hydroxyethylidenediphosphonate ((186)Re HEDP) after failed treatment with medication--initial results of a prospective study.

Eight patients (77 joints) with polyarthritis were treated systemically with 570 MBq (15.4 mCi) of rhenium 186 ((186)Re) hydroxyethylidenediphosphonate (HEDP). Pain and disease activity were assessed monthly. In six (75%) of eight patients, a single injection of (186)Re HEDP led to an improvement in disease activity. Systemic low-dose treatment with (186)Re HEDP can reduce pain and disease activity in patients with polyarthritis.

FDG PET and immunoscintigraphy with 99mTc-labeled antibody fragments for detection of the recurrence of colorectal carcinoma.

UNLABELLED: The aim of this study was to compare FDG PET with a new monoclonal antibody-based imaging agent that comprises an anti-carcinoembryonic antigen (CEA) monoclonal antibody Fab' fragment directly labeled with 99mTc. METHODS: Twenty-eight patients who were previously treated for colorectal carcinoma and in whom recurrence was suspected were examined with FDG PET and immunoscintigraphy. The most common indications were an elevation of serum CEA (13 patients), suggestive lesions documented by CT (9 patients), sonography (4 patients), and severe constipation (2 patients). Planar imaging and SPECT were performed 4-6 h after intravenous injection of the new imaging agent. Whole-body PET was performed 45-60 min after intravenous injection of FDG. The findings were confirmed by conventional diagnostic modalities, surgery, and histology. RESULTS: Histology confirmed local tumor recurrence in 9 of 28 patients. Clinical follow-up or CT confirmed the presence of liver metastases in 9 patients and lymph node involvement, lung metastases, and bone metastases in 2 patients each. The new agent correctly detected 8 of 9 local recurrences, whereas FDG PET was able to detect all 9 cases and in 1 case was false-positive. Liver metastases were confirmed in 9 patients by FDG PET but in only 1 patient by the new agent. Two cases with lymph node metastases and 2 cases with lung metastases were correctly identified by FDG PET, but none were detected by the new agent. Finally, bone metastases were identified in 1 patient by FDG PET but not with the new agent, whereas bone marrow infiltration (n = 1) was diagnosed by both imaging modalities. CONCLUSION: These results indicate that FDG PET and 99mTc-labeled anti-CEA Fab' are suitable for the diagnosis of local recurrence of colorectal carcinoma but that FDG PET is clearly superior in the detection of distant metastases (liver, bone, and lung) and lymph node involvement.

Stimulated acoustic emission: pseudo-Doppler shifts seen during the destruction of nonmoving microbubbles.

The purpose of this study was to evaluate the appearance and the characteristics of stimulated acoustic emission (SAE) as an echo contrast-specific color Doppler phenomenon with impact on myocardial contrast echocardiography (MCE). Stationary microbubbles of the new contrast agent SH-U 563A (Schering AG) were embedded within a tissue-mimicking gel material. Harmonic power Doppler imaging (H-PDI), color Doppler and pulse-wave Doppler data were acquired using an HDI-5000 equipped with a phased-array transducer (1.67/3.3 MHz). In color Doppler mode, bubble destruction resulted in random noise like Doppler signals. PW-Doppler revealed short "pseudo-Doppler" shifts with a broadband frequency spectrum. Quantification of SAE events by H-PDI demonstrated an exponential decay of signal intensities over successive frames. A strong linear relationship was found between bubble concentration and the square root of the linearized H-PDI signal for a range of concentrations of more than two orders of magnitude (R = 0.993, p < 0.0001). Intensity of the H-PDI signals correlated well with emission power (R = 0.96, p = 0.0014). SAE results from disintegration of microbubbles and can be demonstrated by all Doppler imaging modalities, including H-PDI. Intensity of SAE signals is influenced by the applied acoustic power and correlates highly with the concentration of microbubbles. Because intensity of SAE signals correlates highly with echo contrast concentrations, analysis of SAE signals might be used for quantitative MCE.

Liver perfusion scintigraphy prior to and after transjugular intrahepatic portosystemic shunts (TIPS) in patients with portal hypertension.

PURPOSE: This investigation was performed to compare the hemodynamic results of the transjugular intrahepatic portosystemic shunt, a new interventional treatment for portal hypertension, with those observed after the established surgical shunt interventions. METHODS: We examined 22 patients with portal hypertension due to liver cirrhosis before and after elective TIPS by liver perfusion scintigraphy. The relative portal perfusion was determined before and after the shunt procedure. Additionally, we measured the portal pressure gradient (PPG: portal-central venous pressure, mmHg). RESULTS: Prior to TIPS, the relative portal perfusion was significantly reduced to 22 +/- 9.1%. After the intervention we calculated values of 23.1 +/- 10.7% in the TIPS-group (p = 0.67; not significant). In spite of unchanged portal perfusion, the portal pressure was significantly (p < 0.001) reduced from 25.6 +/- 5.3 to 14.8 +/- 4 mm Hg. CONCLUSION: These results suggest that the reduction of portal hypertension by TIPS is effective. The portal perfusion is maintained by TIPS suggesting that liver perfusion is preserved to a higher degree.

Detection of somatostatin receptor-positive tumours using the new 99mTc-tricine-HYNIC-D-Phe1-Tyr3-octreotide: first results in patients and comparison with 111In-DTPA-D-Phe1-octreotide.

Indium- 111 labelled DTPA-D-Phe1-octreotide (DTPA-OC, OctreoScan) has been introduced into clinical routine for the detection of somatostatin receptor (SSTR)-positive tumours, which are predominantly of neuroendocrine origin. Potential further applications in other SSTR-positive cancers (e.g. small cell lung cancer, breast cancer, melanoma) have been limited mainly by the restricted availability and the high radionuclide costs. Previous attempts to introduce technetium-99m labelled analogues of octreotide have not been very successful in terms of the labelling procedure, in vivo biodistribution and/or tumour detection capabilities. The aim of this study was to assess the performance of the new 99mTc-labelled analogue HYNIC-D-Phe1-Tyr3-octreotide (HYNIC-TOC), using tricine as co-ligand, for the detection of SSTR-positive tumours in patients in comparison with 111In-DTPA-OC. Overall, 13 patients were examined using 99mTc-tricine-HYNIC-TOC. Twelve patients had proven SSTR-positive tumours, while one patient presented with an SSTR-negative tumour. In 9 of the 13 patients both tracers (99mTc-tricine-HYNIC-TOC and 111In-DTPA-OC) were used. Serial whole-body scans, spot views and/or single-photon emission tomography studies were performed. Images were qualitatively and semi-quantitatively (ROI analyses) evaluated. The biodistribution of 99mTc-tricine-HYNIC-TOC in patients showed high physiological uptake in kidneys, moderate uptake in liver and spleen and little uptake in the gut. The tracer showed predominantly renal and negligible hepatobiliary excretion. Known SSTR-positive tumour sites showed rapid and intense tracer accumulation. 99mTc-tricine-HYNIC-TOC demonstrated rapid tissue uptake within the first hour after injection and had basically no significant clearance (<20%) from normal or tumour tissue thereafter. In contrast, 111In-DTPA-OC showed continuous clearance from normal tissues as well as renal and very little hepatobiliary excretion. Nevertheless, the patterns of accumulation of 99mTc-tricine-HYNIC-TOC in tumours and normal organs were comparable to those of 111In-DTPA-OC. A lesion-by-lesion comparison showed comparable tumour detection capabilities in intrahepatic tumour sites and superior capabilities of 99mTc-tricine-HYNIC-TOC in respect of extrahepatic lesions. In conclusion, 99mTc-tricine-HYNIC-TOC shows promise as a tracer for SSTR imaging, given its favourable clinical characteristics (specific and high receptor affinity, good biodistribution, renal excretion, low radiation exposure, high imaging quality, on-demand availability) and cost-effectiveness. 99mTc-tricine-HYNIC-TOC allows earlier diagnosis (10 min-4 h) compared with 111In-DTPA-OC (4-24 h).

Myocardial uptake of technetium-99m-furifosmin (Q12) versus technetium-99m-sestamibi (MIBI).

AIM: This study was performed to compare the myocardial uptake of Tc-99m-furifosmin (Q12) versus Tc-99m-sestamibi (MIBI) in correlation to the whole-body uptake under resting conditions. METHODS: 21 patients with coronary artery disease and no rest ischemia were examined. A whole-body scan was performed 60 min. p.i. under resting conditions. A quantification of the uptake (whole-body, heart and right lung) was done by ROI technique. RESULTS: The heart-to-lung ratio of Q12 (1.56 +/- 0.191) was significantly lower as compared to MIBI (1.94 +/- 0.197; p < 0.01). In contrast, the heart-to-whole-body ratios (Q12 versus MIBI: 0.027 +/- 0.012 versus 0.026 +/- 0.004; p < 0.76) did not differ. The lung-to-whole-body ratio (Q12 versus MIBI: 0.018 +/- 0.009 versus 0.013 +/- 0.002; p < 0.17) were different, but did not reach significance. CONCLUSION: These data show that under resting conditions the total myocardial uptake of Q12 does not differ significantly from that of MIBI. However, the pulmonary uptake of Q12 is slightly higher, resulting in a significant lower heart-to-lung ratio. These findings imply a lower image quality of Q12 compared to MIBI.

Possible role of FDG-PET in the early prediction of therapy outcome in liver metastases of colorectal cancer.

Nonresectable colorectal cancer metastases in the liver respond to chemotherapy in 20-25% only. Early identification of nonresponders might allow the use of other regimens. In a limited feasibility study, it should be determined whether (a) a single high-dose chemotherapy application has an early effect on glucose-utilization, detectable and quantitatable by noninvasive positron emission tomography using [18F]-Fluoro-deoxyglucose (FDG-PET) and (b) assess its value as a predictor of the final therapeutic outcome. A total of 10 patients with documented nonresectable liver metastases of a colorectal cancer were studied by FDG-PET, prior and 72 h after a single infusion of 5-Fluorouracil and Folinic acid (5-FU/FA). Glucose utilization was quantitated by determination of standard-uptake values and correlated with final therapy outcome following completion of the anticipated therapy cycle. Patients were followed up for at least 6 months. All metastases responding to therapy (n = 6) exerted a statistically significant decrease of FDG uptake (-22+/-10%), metastases (n = 2) showing a short-term effect (duration of tumor reduction <3 months) had a slightly diminished, and progressing metastases (n = 3) an enhanced FDG uptake (13+/-17%). Our preliminary data indicate that acute changes of glucose utilization-as detected by FDG-PET-following a single application of chemotherapy, seems to be indicative for the final therapeutic outcome, at least in liver metastases of colorectal cancer.