Takashi Togawa

Evaluation of the therapeutic effect of radiotherapy on cervical cancer using magnetic resonance imaging

PURPOSE This study was performed to evaluate magnetic resonance imaging (MRI) in determining the therapeutic effect of radiotherapy (RT) on cervical cancer. METHODS AND MATERIALS Serial MRI studies were performed in 42 patients with predominantly advanced cervical cancer before, during, and after radiotherapy. Patients underwent external irradiation combined with high-dose-rate intracavitary (HDR) brachytherapy. T-2 weighted spin-echo pulse sequences with long repetition and echo times were used at a field strength of 1.5 T. Multiple punch biopsies of the cervix were obtained from the high-signal intensity area in all patients at the same time as the MRI. RESULT In biopsies performed immediately after RT, no residual tumors were found in 36 patients (86%); in 6 patients, residual tumors were observed. The simultaneous MRI study demonstrated no high-signal intensity on T2-weighted images in 28 patients. A high-signal area was observed in 14 patients, and this disappeared 3 months after RT in 8 patients with a negative histological study. The sensitivity, specificity, and accuracy of MRI studies at 3 months after RT were 100%. When the relationship between reduction of tumor volume at 30 Gy and local tumor control was analyzed, every patient with a reduction under 30% gained local control. Also, patients with no residual tumors 3 months after RT gained local control. CONCLUSION MRI studies performed at 30 Gy of external irradiation and 3 months after RT were predictive factors of local control.

Comparison of Vascularized Supraclavicular Lymph Node Transfer and Lymphaticovenular Anastomosis for Advanced Stage Lower Extremity Lymphedema

BackgroundVascularized lymph node transfer has become a popular surgical option to improve lower extremity lymphedema (LEL), although potential donor sites are limited. The free supraclavicular flap with deep cervical lymph nodes has been recently associated with a minimal risk of secondary lymphedema caused by donor site dissection. However, the effectiveness of this procedure has not yet been evaluated. MethodsVascularized supraclavicular lymph node transfer (VSLNT) was performed for patients with International Society of Lymphology late stage II or more severe LEL. The results were compared with lymphaticovenular anastomosis (LVA) performed for patients with the same stages of severity. To evaluate improvement in lymphatic function, indocyanine green lymphography and lymphoscintigraphy were performed. ResultsVascularized supraclavicular lymph node transfer was performed in 13 limbs of 13 patients. The results were compared with 43 limbs of 33 patients who underwent multiple LVA. No severe complications were observed in either group. Improvement in lymphatic function, as measured by the LEL index, was 26.5 ± 4.4 and 21.2 ± 2.0 in the VSLNT and LVA groups, respectively. Lymphatic function was improved in 7 cases in the VSLNT group and 10 cases in the LVA group. ConclusionsVascularized supraclavicular lymph node transfer is an effective technique for the treatment of advanced stage LEL. Lymphaticovenular anastomosis is also effective, but to a lesser degree than VSLNT. However, LVA is less invasive and requires a shorter hospital stay.

Visualization of nasopharyngeal carcinoma with Tl-201 chloride and a three-head rotating gamma camera SPECT system

Tl-201 SPECT was performed on 12 patients with Nasopharyngeal carcinoma (NPC) by means of a three-head rotating gamma camera to evaluate whether or not Tl-201 SPECT was useful and reliable for assessing the tumor viability of NPC. Tl-201 clearly accumulated in the tumor in 3 patients before radiation treatment and increased Tl-201 uptake by the lesion ceased after the treatment. Three of 9 patients who were followed up after radiotherapy developed apparent local recurrence and Tl-201 SPECT clearly visualized these recurrent lesions. Tl-201 SPECT was very useful for assessing the tumor response to irradiation and for detecting local recurrent tumor. A High resolution SPECT system employing Tl-201 chloride is a new reliable and accurate diagnostic tool for the assessment of NPC.

The effect of steroid on thallium-201 uptake by malignant gliomas

In order to assess the effect of steroid on thallium-201 uptake by glioma,201TI single-photon emission tomography was performed before and after steroid administration in four patients with recurrent malignant glioma. After steroid administration the201Tl index, expressed as the ratio of201Tl uptake in the tumour to that in the contralateral cerebral hemisphere, was 0.77±0.11 of the value before steroid (mean±SD:P<0.05 by pairedt test). The201Tl index has been used as a possible indicator for the differentiation of malignant gliomas from relatively benign tumours or radiation necrosis. The present results indicate that the effect of steroid has to be taken into account when semi-quantitative analysis, e.g. by means of the201Tl index, is used in patients with brain tumours.

Optimization of Butterworth filter for brain SPECT imaging

A method has been described to optimize the cutoff frequency of the Butterworth filter for brain SPECT imaging. Since a computer simulation study has demonstrated that separation between an object signal and the random noise in projection images in a spatial-frequency domain is influenced by the total number of counts, the cutoff frequency of the Butterworth filter should be optimized for individual subjects according to total counts in a study. To reveal the relationship between the optimal cutoff frequencies and total counts in brain SPECT study, we used a normal volunteer and99mTc hexamethyl-propyleneamine oxime (HMPAO) to obtain projection sets with different total counts. High quality images were created from a projection set with an acquisition time of 300-seconds per projection. The filter was optimized by calculating mean square errors from high quality images visually inspecting filtered reconstructed images. Dependence between total counts and optimal cutoff frequencies was clearly demonstrated in a nomogram. Using this nomogram, the optimal cutoff frequency for each study can be estimated from total counts, maximizing visual image quality. The results suggest that the cutoff frequency of Butterworth filter should be determined by referring to total counts in each study.

Quantifying brain tumor blood flow by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine super-early SPECT

Regional cerebral blood flow was quantitatively measured in 6 patients with brain tumor by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine (IMP) “super-early” single photon emission computed tomography (SPECT) images obtained 4–6 min after IMP injection with a three-head rotating gamma camera. The ratio of radioactivities (counts/pixel/min) in the “early” SPECT images (taken 25–55 min after IMP injection) to the “super-early” images of the brain tumors was 1.47 ± 0.13 (mean ± SD, n = 6), which was significantly lower than the ratio in the normal cerebral cortices (1.93 ± 0.25) (p < 0.01). This indicates faster clearance of IMP from the tumor tissue than that from the normal brain tissue. Blood flow values for the brain tumors obtained by the microsphere model based on the “super-early” SPECT images were 39.3 ± 12.4 ml/100 g/ min, which was similar to the blood flow values for normal gray matter and in agreement with previous studies with positron emission tomography.

Thallium-201 single-photon emission tomography in the treatment follow-up of nasopharyngeal carcinoma

In order to assess the usefulness of thallium-201 single-photon emission tomography (SPET) in the treatment follow-up of nasopharyngeal carcinoma (NPC), a total of 75201Tl SPET studies were performed in 18 patients with histologically proven NPC. The findings were compared with those of magnetic resonance imaging (MRI) before and after therapy. Four patients received radiotherapy alone while the other 14 received concurrent chemo-radiotherapy. Treatment response was classified as complete (CR) or partial (PR) based on the findings of MRI and201Tl SPET. Intense201Tl uptake by the tumour was seen in all 18 patients before treatment. After treatment, MRI showed seven CRs and 11 PRs, whereas201Tl SPET showed 13 CRs and five PRs. In 12 patients, the results of201Tl SPET were in agreement with those of MRI. In six patients MRI showed PR but201Tl showed CR. Follow-up (mean 10.6 months) MRI and201Tl SPET studies of these six patients revealed that tumour gradually decreased and finally vanished in three patients. This preliminary study indicates that201Tl SPET has potential in the assessment of early response to treatment of patients with NPC when compared with MRI.

Comparison of barium swallow, CT and thallium-201 SPECT in evaluating responses of patients with esophageal squamous cell carcinoma to preoperative chemoradiotherapy

The aims of this study were to compare the results of thallium-201 (Tl-201) SPECT, barium swallow and CT in the assessment of the effect of preoperative chemoradiotherapy. This study consisted of 28 patients with advanced esophageal squamous cell carcinoma (AESCC) who underwent the three imaging modalities before and after preoperative chemoradiotherapy. The results were quantified using the bidimensional method for barium swallow and contrast-enhanced CT and the tumor-to-lung ratio for SPECT. The percent decrease in these quantitative values after therapy was defined as %Dba, %Dct and %Dtl respectively. The histological effect of the chemoradiotherapy was determined from the resected surgical specimen of the esophagus: grade 0, 100% viable tumor cells; grade la, 99–67%; grade 1 b, 66–34%; grade 2, 33–1%; grade 3, no viable cells. A statistically significant difference of %Dtl between the subgroups of each grade was evident (p=0.0433), whereas no significant differences were evident for %Dba (p=0.1778) or %Dct (p=0.7377). However, the overlap of %Dtl between these groups was marked. Although thallium-201 SPECT cannot be used to evaluate the therapeutic effect with acceptable accuracy, SPECT may be of additional value to barium swallow and CT in assessing the response of AESCC to preoperative chemoradiotherapy.

Extraosseous accumulation of 99mTc phosphonate complexes in primary brain tumor evaluated with SPECT.

Although extraosseous accumulations of99mTc phosphate complexes are phenomena which can often be seen, no case showing extraosseous accumulation to brain tumor on SPECT has been reported. We report here two cases of primary brain tumor showing extraosseous accumulation of99mTc phosphate in bone SPECT.201Tl SPECT also showed increased201Tl uptake by the tumor. Comparing bone SPECT with201Tl SPECT, the regions of abnormality of both SPECTs were very similar in the case of glioblastoma, but in the case of malignant lymphoma the region showing intense uptake of99mTc-MDP was smaller than that on201Tl SPECT. It was revealed that bone SPECT is more useful in the assessment of extraosseous accumulation to a primary brain tumor than conventional bone scintigraphy.

Evaluation of mandibular invasion by head and neck cancers using 99mTc-methylene diphosphonate or 99mTc-hydroxymethylene diphosphonate and 201Tl chloride dual isotope single photon emission computed tomography

Whether a patient with head and neck cancer has mandibular invasion or not is important in determining the method of resection surgery. But, no modality is adequately reliable when used alone in the evaluation of mandibular invasion. Therefore, to more accurately diagnose mandibular invasion in head and neck cancer, we used a new modality, namely,99mTc methylene diphosphonate (MDP) or 99mTc hydroxymethylene diphosphonate (HMDP) and201Tl chloride dual isotope single photon emission computed tomography (Tc/T1 SPECT). The aim of this study is to disclose the usefulness of Tc/Tl SPECT in the assessment of mandibular invasion by head and neck cancers.99mTc-MDP or -HMDP SPECT (Tc SPECT)s and201T1 chloride SPECT (Tl SPECT)s were performed in 34 patients with suspected mandibular involvement of head and neck cancer. Thirty of 34 cases underwent both Tc/Tl SPECT and CT examination. Tc/Tl SPECT fusion images were obtained using the Automatic Registration Tool (ART, TOSHIBA, Japan) system. In the diagnosis of mandibular invasion on Tc/Tl SPECT fusion images, a problem was that the range of Tc and Tl uptake was changed by the condition of display used in the reconstruction and expression of the images. Then, prior to clinical evaluation, to reveal the most appropriate upper window level for display, a phantom study was performed. In a clinical study, the upper window level was set at 40 or 50%, which were verified to be the proper values in the preliminary study. The diagnostic accuracy obtained using Tc SPECT, Tc/Tl SPECT and CT was compared with the histopathological findings. Tc/Tl SPECT at 40 and 50% upper window level had higher specificity, accuracy, and positive predictive value (73.3%, 85.3%, 81.8%) than Tc SPECT alone (21.4%, 67.6%, 64.5%) and higher sensitivity and negative predictive value (94.7%, 91.7%) than CT (70.6%, 72.2%) for detecting mandibular invasion. Tc/Tl SPECT was a useful diagnostic procedure for the assessment of mandibular invasion by head and neck cancers.