Search

Purpose: To find out if single-photon emission computed tomography (SPECT) and (123)I-subtraction can enhance the findings of (99m)Tc-methoxyisobutylisonitrile (MIBI) scintigraphy for the preoperative localization of parathyroid (PT) tumors., Methods: Among the 111 consecutive patients who underwent preoperative planar (99m)Tc-MIBI scintigraphy for hyperparathyroidism (HPT), 64 underwent delayed SPECT, and 17 underwent (123)I-subtraction. Two independent blinded experts scored the topographical localization, diagnostic confidence, and impact of each diagnostic modality on the surgical strategy., Results: For adenomas, (99m)Tc-MIBI scintigraphy had a sensitivity of 77% with a positive predictive value (PPV) of 83%. SPECT did not affect the sensitivity or PPV, but it increased the diagnostic confidence and changed the surgical strategy in 21% of the patients. (123)I-subtraction increased the sensitivity from 64% to 82%, but decreased the PPV from 88% to 82%. In hyperplastic glands, (99m)Tc-MIBI scintigraphy had a sensitivity of 47% and a PPV of 95%. When (99m)Tc-MIBI scintigraphy was combined with SPECT and (123)I-subtraction, the results were 44%/10% and 52%/92%, respectively. Both SPECT and (123)I-subtraction decreased the diagnostic confidence., Conclusions: Adding SPECT to (99m)Tc-MIBI scintigraphy improved the surgical decision for parathyroid adenomas. The addition of (123)I-subtraction was of limited value. For hyperplastic glands, (99m)Tc-MIBI scintigraphy was relatively ineffective, even with the addition of SPECT or (123)I-subtraction.

The aim of this study was to determine the yield of attenuation correction in myocardial perfusion imaging (MPI), before and after a 1-year experience period. In 48 consecutive patients referred for MPI, both non-corrected (NC) and attenuation-corrected (AC) images were analysed by three independent readers shortly after implementation of attenuation correction. The same images were re-analysed 1 year later, after having obtained experience in attenuation correction on a routine basis in >500 patients with clinical feedback. Results were compared with gold standards for ischaemia and infarction based on coronary angiography, follow-up, ultrasound and gated blood pool imaging. Sensitivity and specificity for the detection of coronary artery disease were 95% and 45% respectively for NC images and 77% and 70% respectively for AC images at first readings. After 1 year of AC experience, NC sensitivity/specificity was 100%/61%, and AC results were 89%/92%. It is concluded that attenuation correction improves the performance of MPI interpretation. With attenuation correction, specificity is increased and sensitivity is similar as compared with NC images. However, attenuation correction requires experience and is associated with a learning curve.

Unlabelled: PET with L-1-(11)C-tyrosine (TYR) can measure and quantify increased protein synthesis in tumor tissue in vivo. For quantification of the protein synthesis rate (PSR), arterial cannulation with repeated blood sampling to obtain the plasma input function and a dynamic TYR PET study to calculate a time-activity curve are necessary. In most PET studies the standardized uptake value (SUV) method is used to quantify tumor activity. The SUV can be calculated without repeated arterial blood sampling and prolonged scanning time, as required for determination of the PSR. The relationship between PSR and SUV is largely unknown and different factors can cause wide variability in the SUV. Therefore, the comparison of the absolute quantification method (PSR) with the SUV method is obligatory to determine the possible use of noninvasive PET in head and neck oncology., Methods: Twenty-four patients with proven squamous cell carcinomas of the larynx (T1-T4) were studied using dynamic TYR PET. The PSRs of tumor and nontumor (background) regions were determined. Four different methods were used to calculate the SUV: uncorrected SUV (SUV(BW)); and SUVs corrected for body surface area (SUV(BSA)), for lean body mass (SUV(LBM)), and for the Quetelet index (SUV(QI)). Correlations between PSR values and SUVs were calculated., Results: The PSR of all tumors was significantly higher (P < 0.001) than the PSR of nontumor tissue. The correlations of SUV(BW), SUV(BSA), SUV(LBM), and SUV(QI) with the quantitative values of the PSR were high (r = 0.84-0.90). The best correlation was observed with the SUV based on the LBM (SUV(LBM))., Conclusion: High correlation between the quantitative values (PSR) and the SUVs offers the possibility to use noninvasive TYR PET for detection and reliable quantification of primary head and neck tumors.

Unlabelled: PET with (18)F-FDG is used for detection and staging of thoracic cancer; however, more specific PET radiopharmaceuticals would be welcome. (11)C-labeled choline (CHOL) is a new radiopharmaceutical potentially useful for tumor imaging, since it is incorporated into cell membranes as phosphatidylcholine. The aim of this study was to investigate whether (11)C-CHOL PET has advantages over (18)F-FDG PET in patients with thoracic cancer., Methods: We evaluated 17 patients with thoracic cancer both with (11)C-CHOL PET and (18)F-FDG PET. After transmission scanning, (11)C-CHOL was injected intravenously, and whole-body scanning was started after 5 min. Immediately thereafter, (18)F-FDG was injected intravenously, followed after 90 min by interleaved attenuation-corrected whole-body scanning. Scans were performed from crown to femur. Visual and quantitative (standardized uptake value) analyses of (11)C-CHOL PET and (18)F-FDG PET were performed and compared with results of traditional staging and follow-up., Results: The most prominent features of normal (11)C-CHOL distribution were high uptake in liver, renal cortex, and salivary glands. Except for some uptake in choroid plexus and pituitary gland, brain uptake was negligible. All primary thoracic tumors were detected with (11)C-CHOL PET and (18)F-FDG PET. Both (11)C-CHOL PET and (18)F-FDG PET correctly identified all 16 patients with lymph node involvement. However, in a lesion-to-lesion analysis, (11)C-CHOL PET detected only 29 of 43 metastatic lymph nodes, whereas (18)F-FDG PET detected 41 of 43. (11)C-CHOL PET detected fewer intrapulmonary and pleural metastases than (18)F-FDG PET (27/47 vs. 46/47). More brain metastases were detected with (11)C-CHOL PET (23/23) than with (18)F-FDG PET (3/23). For primary tumors, the median (range) standard uptake values of (11)C-CHOL and (18)F-FDG were 1.68 (0.98-3.22) and 4.22 (1.40-8.26), respectively (P = 0.001)., Conclusion: (11)C-CHOL PET can be used to visualize thoracic cancers. Although detection of lymph node metastases with (11)C-CHOL PET was inferior compared with (18)F-FDG PET, the detection of brain metastases was superior.

We investigated the feasibility of using carbon-11 choline (CHOL) positron emission tomography (PET) for the staging of oesophageal cancer, in comparison with fluorine-18 fluorodeoxyglucose (FDG) PET, using histopathological findings as the gold standard. Eighteen patients were studied: 16 patients with cancer of the oesophagus or gastro-oesophageal junction and two with in situ carcinoma/high-grade dysplasia. PET imaging was performed 5 min (CHOL) or 90 min (FDG) after injection of 370 MBq of the tracer. PET images were analysed by two independent and blinded physicians using visual and standardised uptake value (SUV) analysis. PET results were compared with surgical and histopathological findings. FDG-PET was able to detect all (100%) of the 16 malignant primary lesions, while CHOL-PET detected 73%. In situ carcinoma ( n=1) and high-grade dysplasia ( n=1) were not visualised with either tracer. Diffuse uptake of the tracers was noted in areas of Barrett's oesophagitis. Twelve patients had locoregional metastases (N1) that were not detected with either FDG or CHOL. Six patients had additional distant nodal (M1a) metastases; four of six (66%) were visualised by FDG, and three of five (60%) by CHOL-PET. On a lesion basis, FDG-PET detected 10/12 non-regional metastases (sensitivity 83%), while CHOL-PET detected 5/12 (sensitivity 42%). Haematogenous distant metastases (M1b) were positive on FDG-PET in three of four patients, and on CHOL-PET in two of four. SUV values were significantly higher for FDG (FDG 6.6+/-3.5, CHOL 5.5+/-2.5, P=0.04). CHOL-PET is able to visualise oesophageal carcinoma and its metastases, but appears to be inferior to FDG-PET. Presumably this is the result of lower tumoural uptake and considerable non-specific uptake of CHOL in liver, stomach wall, pancreas and small intestine. Further studies are needed to confirm these data.

We have investigated the role of immunophenotyping in distinguishing between leukemic B-cell lymphoproliferative disorders. Circulating cells from 666 cases were analyzed with a panel of markers by flow cytometry. The diseases included: chronic lymphocytic leukemia (CLL), 400; prolymphocytic leukemia, 22; hairy cell leukemia (HCL), 40; HCL variant, 15; splenic lymphoma with villous lymphocytes, 100; follicular lymphoma, 26; lymphoplasmacytic lymphoma, 25; mantle-cell lymphoma, 20; and large cell lymphoma, 18. On the basis of the most common marker profile in CLL, CD5+, CD23+, FMC7- and weak expression (+/-) of surface immunoglobulin (SmIg) and CD22, we devised a scoring system that gives for each of these five markers a value of 1 or 0 according to whether it is typical or atypical for CLL. Scores range from 5 (typical of CLL) to 0 (atypical for CLL). Application of the scoring system to all the cases showed that 87% of CLL scored 5 and 4 and only 0.4% scored 0 or 1, whereas 89% of other B-cell leukemias and 72% of lymphomas scored 0 or 1; only one case (0.3%) scored 4 and none scored 5 (p < 0.0001). There were no differences between CLL with high and low scores but higher scores were found in cases with more typical morphology (p < 0.0015). Considering each individual marker, there was no single one that distinguished CLL from other diseases, although the most reliable were SmIg intensity and FMC7. The proposed score will facilitate the diagnosis of B-lymphoproliferative disorders and improve their classification.

Fluorescence in situ hybridization (FISH) with a chromosome 12 specific alpha-centromeric probe was performed on interphase cells from 183 patients with B-cell chronic lymphocytic leukemia (CLL). Twenty one cases with trisomy 12 (11.5%) were detected. The number of trisomic cells ranged from 5.5% to 76% (mean 38.5%). No correlation was found between the presence of trisomy 12 and white blood cell count, hemoglobin level, platelet count, a specific immunophenotype, clinical stage, sex, splenomegaly, or lymphadenopathy. Morphologic review of all cases with trisomy 12 showed seven (33%) with more than 10% prolymphocytes and three (14%) with CLL of mixed cell type. While trisomy 12 is the most common chromosomal abnormality in CLL, it is more frequent in morphologically atypical cases, some of which may be undergoing transformation. There was a statistically significant difference in the incidence of atypical cases between those with (47%) and without (7.6%) trisomy 12 (P < .001). It remains to be determined whether this abnormality is associated with a worse prognosis; this is currently being investigated in the context of a national therapeutic trial. The technique used is more sensitive than conventional cytogenetic analysis, which in this series failed to detect trisomy 12 in six cases. FISH allows the systematic study on a large number of patients without the need of metaphase preparations.