Pre-Treatment and Post-Treatment I-131 Imaging in Differentiated Thyroid Carcinoma

Radioiodine imaging in initial perioperative settings, after the total thyroidectomy, includes pre-treatment and post-treatment radioiodine imaging. While the benefit of post-treatment whole-body imaging (PT-WBI) is well established, the role of diagnostic whole-body imaging (dx WBI), prior to radioiodine (I-131) ablative or therapeutic doses, is controversial. Dx WBI has been abandoned in most nuclear medicine centers long ago. Planar low-dose dxWBI provides the volume of postoperative thyroid remnants, but it cannot detect occult metastatic foci in the neck. The modern integrated multimodality, i.e., SPECT/CT imaging, provides three dimensional images and accurate anatomic/metabolic data. This hybrid technology offers better spatial resolution but not better sensitivity. Dx WBI has low theranostic power because of the radioiodine indifference and low detection sensitivity for small-volume nodal disease in the neck. Since dx WBI cannot clarify the paratracheal cervical uptake, thyroid remnants may be easily misinterpreted as nodal disease, leading to a false N upstaging (from N0 stage to N1 stage) in DTC patients. Post-ablation I-131 imaging has a significant role in the initial staging of radioiodine-avid DTC and in the identification of non-radioiodine avid tumors. Additionally, SPECT/CT in the post-treatment setting provides more accurate initial TNM staging and better risk stratification of DTC patients. Post-treatment I-131 imaging is obligatory and must be performed in all DTC patients who receive radioiodine treatment.

Lung tumors: early and delayed ratio of 99mTc-methoxy-2-isobutylisonitrile accumulation

BACKGROUND/AIM

Currently used radiopharmaceuticals are nonspecific and most of them are accumulated by benign tumors as well as inflammatory lesions, abscess or granulomatous lesions. Some factors such as the choice of radiopharmaceutical applied, histopathologic type of tumor, its size, location or previous tumor treatment could influence tumor imaging sensitivity. The aim of this study was to investigate accumulation of 99mTc-methoxy-2-isobutylisonitrile (99mTc-MIBI) by counting early/delayed uptake and release of this radiopharmaceutical inside lung tumors and evaluating possible factors which could be involved in its accumulation.

METHODS

Two-phase 99mTc-methoxy-2-isobutylisonitrile single photon emission computed tomography scan (early and delayed scan) was performed in 60 patients with lung tumors (the group 1 - 30 benign, and the group 2 - 30 malignant tumors). We calculated the uptake ratio on early (early ratio - ER), delayed images (delayed ratio - DR) and retention index (RI). Individual influence of etiology, diameter, localization, and histological type on uptake/release values was evaluated with regression analysis.

RESULTS

The values of ER and DR were significantly different in both groups (p < 0.01), showing lower values in benign vs malignant lung tumors (ER 1.36 ± 0.094 and DR 1.25 ± 0.089 vs ER = 1.93 ± 0.106 and DR = 1.7 ± 0.095 respectively). Tumor size showed a significant influence on the change of ER and DR values (p < 0.01), with greater uptake in tumors > 3 cm. RI values showed no significance between the two groups (P > 0.05).

CONCLUSION

The uptake ratio of 99mTc-methoxy-2-isobutylisonitrile could be a useful index in differentiating lung tumors, while RI has no influence on this. Among the evaluated factors, ER and DR values are significantly influenced only by the diameter of lung tumor, while localization or different histological types between the groups has no influence on this.

Importance of positron emission tomography-computed tomography (PET-CT) examination in rectal cancer staging--initial clinical experience

AIM

Accurate preoperative staging is essential in determining optimal therapeutic procedures and planning for individual patients. Advances in imaging technology have raised interest in the potential role of positron emission tomography-computed tomography (PET-CT) examination for staging of rectal cancer. The primary end point of the study was the correct classification of the tumor node-metastases (TNM) tumor stage using whole-body PET-CT examination.

METHODS

This prospective study was performed from October 2011 to October 2012. Patients with histopathological diagnosis of rectal cancer after biopsy underwent PET-CT before surgical treatment and TNM staging. Twenty patients who fulfilled inclusion criteria were included in the study. All of the patients were operated and histopathology served as the standard of reference.

RESULTS

There was no statistical significance in T staging comparing PET-CT and histopathological staging, according to the Monte Carlo simulation (p=.066). Also, there was no statistical significance between two methods in mesorectal fascia involvement analysis (p=1). There was statistical difference between PET-CT and histopathological staging. Sensitivity of the PET-CT for N staging was 86.7% and it was higher than for the histopathology. Two patients showed liver metastases.

CONCLUSION

Positron emission tomography-computed tomography examination could play an important role in the initial staging for the rectal cancer. Good patient selection for preoperative chemoradiotherapy ensures survival benefit. Avoidance of unnecessary therapeutic procedures allows an acceptable quality of patient's life.

Magnetic resonance imaging in diagnostic algorithm of solitary cold thyroid nodules

PURPOSE

This study was performed to determine the role of magnetic resonance imaging (MRI) in a diagnostic algorithm for thyroid nodules.

PATIENTS AND METHODS

Forty-four patients with solitary "cold" thyroid nodules were included in our study. MR images were analyzed visually.

RESULTS

Benign nodules were shown as sharply marginated lesions classified by various signal intensity depending on nodule content. Thyroid carcinomas were shown as isointense or slightly hypointense lesions on T1-weighted images and hyperintense inhomogeneous lesions on T2-weighted images compared to normal thyroid tissue; following contrast, malignancies showed marked enhancement in most of the cases.

CONCLUSION

In a thyroid diagnostic algorithm, conventional procedures such as ultrasound with fine needle aspiration and radionuclide scintigraphy should be performed first. In comparison with computed tomography (CT), MRI is superior because of better spatial resolution and the absence of ionizing radiation. MRI has its place in the staging of thyroid carcinoma and the preoperative assessment of the extent of malignant invasion of surrounding neck structures.

[131-I-lipiodol in therapy of liver carcinoma--methods and case report]

INTRODUCTION

Primary malignant liver tumors are successfully treated only by means of surgery, but no more than 10% of patients are candidates for surgical intervention. The rest receive only palliative treatment which is, as a rule, unsuccessful. 131I-Lipiodol therapy (commercial label LIPIOCISTM) applied to the hepatic artery through a catheter has been used since 1984, primarily for treatment of hepatocellular carcinoma (HCC). The aim of this paper is to review the methodology of 131J-Lipiodol treatment of primary liver carcinomas. This treatment was applied for the first time in Yugoslavia.

CASE REPORT

A female patient, 46 years of age had an inoperable primary liver carcinoma. Since progression of the disease couldn't be controlled by chemotherapy, treatment with 131I-Lipiodol was indicated. After blocking the thyroid with Lugol, Sol. 2.22 GBq of 131I-Lipiodol was injected into hepatic artery via catheter, and the patient was isolated in a designated facility until discharged. Around 5 months later, second therapeutic dose of 1.11 GBq was administered. Early post-therapy complications were severe, but transient. After 131I-Lipiodol therapy, the tumor growth was stopped, but the patient's general condition slowly deteriorated. The patient died 7 months after receiving the first therapeutic dose.

CONCLUSION

In the reported patient, 131I-Lipiodol therapy stopped the tumor growth within the liver and significantly prolonged survival compared to the expected, but no improvement in quality of life was achieved. This treatment methodology is very complex. Medical staff providing care for these patients is exposed to substantial irradiation.

[The role and value of perfusion parameters in clinical discrimination of "cold" thyroid nodes]

The aim of the study was to investigate if the perfusion parameters can be of value in differential diagnosis of "cold" thyroid nodes. This procedure was performed in 60 patients with "cold" unilateral nodes. The quantitative parameters of perfusion through the "cold" nodes were obtained by our own computer programme. The parameters of perfusion which gave the most impressive results are shown in this study. The ratio of perfusion between the node and healthy thyroid lobe was significantly higher in carcinomas (0.8) than in benign "cold" nodes: cysts (0.1), autommune thyroid diseases and benign solid goiters (0.4). The radioactivity increasing rate in node was significantly higher in carcinomas (2.7) than in benign nodes: Cysts (1.3), autoimmune thyroid diseases (1.5) and solid benign goiters (1.6). The ratio of radioactivity increasing rate between the node and healthy thyroid lobe was also significantly higher in carcinomas (0.9) than in other "cold" benign lesions (0.3).