Detecting mediastinal lymph node metastases in non-small-cell lung cancer using a combination of technetium-99m tetrofosmin chest single photon emission computed tomography and chest computed tomography

Single-Photon Emission Computed Tomography/Computed Tomography in Lung Cancer and Malignant Lymphoma

In nuclear oncology, despite the fast-growing diffusion of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), single-photon emission computed tomography (SPECT) studies can still play an useful clinical role in several applications. The main limitation of SPECT imaging with tumor-seeking agents is the lack of the structural delineation of the pathologic processes they detect; this drawback sometimes renders SPECT interpretation difficult and can diminish its diagnostic accuracy. Fusion with morphological studies can overcome this limitation by giving an anatomical map to scintigraphic data. In the past, software-based fusion of independently performed SPECT and CT images proved to be time-consuming and impractical for routine use. The recent development of dual-modality integrated imaging systems that provide functional (SPECT) and anatomical (CT) images in the same scanning session, with the acquired images coregistered by means of the hardware, has opened a new era in this field. The first reports indicate that SPECT/CT is very useful in cancer imaging because it is able to provide further information of clinical value in several cases. In SPECT, studies of lung cancer and malignant lymphomas using different radiopharmaceutical, hybrid images are of value in providing the correct localization of tumor sites, with a precise detection of the involved organs, and the definition of their functional status, and in allowing the exclusion of disease in sites of physiologic tracer uptake. Therefore, in lung cancer and lymphomas, hybrid SPECT/CT can play a role in the diagnosis of the primary tumor, in the staging of the disease, in the follow-up, in the monitoring of therapy, in the detection of recurrence, and in dosimetric estimations for target radionuclide therapy.

Quantitative analysis and effect of attenuation correction on lymph node staging of non-small cell lung cancer on SPECT and CT

OBJECTIVE

The purpose of our study was to assess quantitative indexes and the effect of attenuation correction on the evaluation of lymph node metastasis in the staging of non-small cell lung cancer (NSCLC) using fused thallium-201 SPECT/CT images.

MATERIALS AND METHODS

We evaluated 156 lymph nodes (66 metastatic, 90 nonmetastatic) from 29 patients with NSCLC. Using our combined SPECT/CT system, all patients underwent 201Tl SPECT and CT examinations immediately (early images) and 3 hr after (delayed images) the injection of 201Tl. SPECT images were reconstructed with and without attenuation correction. For the quantitative evaluation of lymph node metastasis, we calculated the early ratio, the delayed ratio, and the washout ratio for SPECT images and the short-axis diameter for CT images. Receiver operating characteristic (ROC) analysis was performed in each index for the differentiation between metastatic and nonmetastatic lymph nodes. Visual analysis was also performed by two experienced radiologists.

RESULTS

The area under the ROC curve (A(z)) showed that early ratio and delayed ratio were superior to short-axis diameter for the assessment of lymph node metastasis. In addition, early and delayed ratios on attenuation-corrected images were superior to those ratios on images without attenuation correction. However, the A(z) value for washout ratio was smaller than that for short-axis diameter. Early ratio on attenuation-corrected images was the most useful index (A(z) = 0.94). The sensitivity, specificity, and accuracy for early ratio on attenuation-corrected images were 78.8%, 94.4%, and 87.8% for the diagnosis of lymph node metastasis and 84.6%, 100%, and 93.1% for clinical staging (N0-N1 vs N2-N3), respectively. Fused images showed significantly higher diagnostic accuracy than CT images on visual analysis.

CONCLUSION

Quantitative assessment using fused SPECT/CT images is useful for the diagnosis of lymph node metastasis in patients with NSCLC.

Usefulness of technetium-99m tetrofosmin liver imaging to detect hepatocellular carcinoma and related to expression of P-glycoprotein or multidrug resistance associated protein-a preliminary report

Technetium-99m Tetrofsomin (Tc-TF) has been shown to be useful in identifying several types of tumors, such as breast, lung, and thyroid cancers. There was no report in the literature for Tc-TF uptake in hepatocellular carcinoma (HCC). The aim of this study was to evaluate the usefulness of Tc-TF liver imaging to detect HCC and investigate the relationship between Tc-TF liver imaging findings and P-glycoprotein (Pgp) and multidrug resistance associated protein (MRP) expression. Before any therapy, 22 patients with HCC were enrolled in this study. Tc-TF liver images were performed l0 minutes after intravenous injection of 20mCi Tc-TF. All patients had liver biopsy or surgery within l week after Tc-TF liver imaging. Immunohistochemical study of the biopsy or resected HCC specimens was performed using anti-human Pgp and MRP antibodies. Twenty of the 22 (90.9%) patients showed negative Tc-TF liver imaging results without significant Tc-TF uptake in HCC, whereas only the remaining 2 (9.1%) patients showed positive Tc-TF liver imaging results with significant Tc-TF uptake in HCC. Positive Pgp expression was observed in 13 of 20 patients with negative Tc-TF liver imaging results, whereas positive MRP expression was observed in 6 of the remaining 7 patients with negative both Tc-TF liver imaging results and Pgp expression. However, negative Pgp expression but positive MRP expression was observed in all of the remaining 2 patients with positive Tc-TF liver imaging results. The correlation between Tc-TF liver imaging findings and Pgp expression was significant and better than between Tc-TF liver imaging findings and MRP expression. Pgp or MRP expression in HCC may induce no significant Tc-TF uptake in HCC resulting in negative Tc-TF liver imaging findings. Therefore, Tc-TF liver imaging is potential to be a non-invasive method to predict Pgp or MRP expression in HCC. However, further studies with a larger series of patients and longer follow-up time are necessary to confirm our findings.

Lung cancer--where are we today? Current advances in staging and nonsurgical treatment

Lung cancer remains the commonest cause of cancer death in both men and women in the developed world, although mortality rates for men are dropping. Spiral computed tomography (CT) of the chest in middle-aged, smoking subjects may identify two to four times more lung cancers than a chest X-ray, with more than 70% of tumors being Stage I. The incidence of benign nodules is high, making interpretation difficult. Randomized controlled trials are required to determine whether spiral CT detects lung cancer early enough to improve mortality. Preoperative staging has relied on CT scans, but positron emission tomography scanning has greater sensitivity, specificity, and accuracy than CT and is recommended as the final confirmatory investigation when the CT shows resectable disease. In locally advanced non-small cell lung cancer, there is a small advantage for the addition of chemotherapy to radiotherapy, but no advantage for postoperative radiotherapy. Chemotherapy gives no benefit when given as neoadjuvant or adjuvant treatment around surgery. In advanced disease, newer cytotoxic agents confer a small survival advantage over older combinations, but the advantage in median survival over best supportive care remains a few months with modest improvements in quality of life. Survival with small cell lung cancer has shown little increase over the last 15 years despite multiple attempts to manipulate the timing, dose intensity of chemotherapy, and the potential of radiotherapy. Novel therapies are urgently needed for all cell types of lung cancer.