Keiichi Ohmori

Image fusion between 18FDG-PET and MRI/CT for radiotherapy planning of oropharyngeal and nasopharyngeal carcinomas

PURPOSE Accurate diagnosis of tumor extent is important in three-dimensional conformal radiotherapy. This study reports the use of image fusion between (18)F-fluoro-2-deoxy-D-glucose positron emission tomography (18FDG-PET) and magnetic resonance imaging/computed tomography (MRI/CT) for better targets delineation in radiotherapy planning of head-and-neck cancers. METHODS AND MATERIALS The subjects consisted of 12 patients with oropharyngeal carcinoma and 9 patients with nasopharyngeal carcinoma (NPC) who were treated with radical radiotherapy between July 1999 and February 2001. Image fusion between 18FDG-PET and MRI/CT was performed using an automatic multimodality image registration algorithm, which used the brain as an internal reference for registration. Gross tumor volume (GTV) was determined based on clinical examination and 18FDG uptake on the fusion images. Clinical target volume (CTV) was determined following the usual pattern of lymph node spread for each disease entity along with the clinical presentation of each patient. RESULTS Except for 3 cases with superficial tumors, all the other primary tumors were detected by 18FDG-PET. The GTV volumes for primary tumors were not changed by image fusion in 19 cases (89%), increased by 49% in one NPC, and decreased by 45% in another NPC. Normal tissue sparing was more easily performed based on clearer GTV and CTV determination on the fusion images. In particular, parotid sparing became possible in 15 patients (71%) whose upper neck areas near the parotid glands were tumor-free by 18FDG-PET. Within a mean follow-up period of 18 months, no recurrence occurred in the areas defined as CTV, which was treated prophylactically, except for 1 patient who experienced nodal recurrence in the CTV and simultaneous primary site recurrence. CONCLUSION This preliminary study showed that image fusion between 18FDG-PET and MRI/CT was useful in GTV and CTV determination in conformal RT, thus sparing normal tissues.

Role of radiotherapy for mucoepidermoid carcinoma of salivary gland.

This report analyzes 61 patients with mucoepidermoid carcinomas of the salivary gland treated by surgery alone or by surgery plus radiotherapy. Local control for all 61 patients at 5 and 10 years was achieved for 88.8 and 79.7% of the cases. Although the rate of positive surgical margin was higher in patients treated with surgery and radiotherapy (radiotherapy group) than in patients treated by surgery alone (surgery group), the local control rates of the two groups showed no statistically significant differences. There was no local recurrence in seven patients receiving post-operative radiotherapy above 55 Gy while there were three local relapses among 17 patients receiving 55 Gy or lower doses (P < 0.05). The 5- and 10-year actual survival rates were 73.4 and 63.3% respectively. Histopathologic subtype of mucoepidermoid carcinomas correlated with regional lymph node involvement and survival. There were no differences in the local control and survival rates of patients with major salivary gland tumors and patients with minor salivary gland tumors. Radiotherapy using 55 Gy or more combined with operation achieved local control and survival rates comparable with complete resection of tumors even if a positive surgical margin was more frequent in the radiotherapy groups.

Ipsilateral irradiation for carcinomas of tonsillar region and soft palate based on computed tomographic simulation.

PURPOSE To reduce xerostomia in selected patients with carcinomas of the tonsillar region and soft palate. METHODS AND MATERIALS We evaluated the treatment results of 32 patients with tonsillar region and soft palate carcinoma treated by radical radiotherapy between May 1989 and December 1996. They have a unilateral tumor that did not cross midline and have no contralateral neck lymphnode metastasis and treated with an ipsilateral technique (an anterior oblique and a posterior oblique field). All patients were planned with computed tomographic (CT) simulation and given 65 Gy in 26 fractions in 6.5 weeks with or without 5-15 Gy boost irradiation. The median follow-up was 44 months (4-86 months). RESULTS Five-year overall, cause-specific survival, local control, and regional control rate was 64, 79, 74 and 81%. No failure at the contralateral neck occurred. Moderate or severe symptomatic xerostomia was seen in 3 (9%) patients and ostero-radionecrosis requiring surgery occurred in one (3.3%) of 32 patients. CONCLUSION It is suggested that the ipsilateral technique is indicated in patients who had an unilateral tonsillar region or soft palate carcinoma that did not cross midline and have no contralateral neck lymphnode metastasis.

Skull-base invasion of nasopharyngeal carcinoma : Magnetic resonance imaging findings and therapeutic implications

PURPOSE To evaluate the value of skull-base abnormality on MRI for predicting local recurrence in nasopharyngeal carcinoma. MATERIALS AND METHODS Between November 1988 and February 1997, 48 patients with NPC were examined with both MRI (1.5 T) and CT prior to radiation therapy. T classification (1987 UICC) based on physical examination and CT findings were T1 in 3 cases, T2 in 22, T3 in 9, and T4 in 14. On MRI, low-intensity tissue with Gd enhancement in the marrow of the skull was considered to be a suspicious finding of skull-base invasion. CT simulation was performed in all patients. The total dose to the primary tumor was 60-75 Gy (mean, 67 Gy). The mean follow-up period was 42 months. RESULTS All 14 T4 patients had abnormal tissue in the marrow of the skull base on MRI. Thirty-eight percent (13 of 34) of T1-3 patients were suspected to have skull-base invasion based on MRI (0% for T1, 27% [6 of 22] for T2, and 78% [7 of 9] for T3). The 5-year local control rate was significantly different between T1-3 and T4 tumors (97% vs. 69%, p < 0.025) but was not different by the presence of the MRI abnormality in the skull base. CONCLUSION Skull-base invasion suspected solely by MRI does not relate to local recurrence provided that careful treatment planning is performed with the aid of MRI and CT simulator.

A comparison of diagnostic tools for Sjögren syndrome, with emphasis on sialography, histopathology, and ultrasonography

OBJECTIVE The present study examined the reliability and correlation of sialography, salivary gland biopsy, and ultrasonography for Sjögren syndrome (SS) and evaluated the usefulness of ultrasonography as a diagnostic tool for SS compared with sialography and histopathology. STUDY DESIGN Seventy-three patients who underwent sialography, ultrasonography, and salivary gland biopsy were included in this study. The study evaluated the diagnostic reliability and correlation of each kind of examination with SS. RESULTS There was a statistically significant difference in the sensitivities of sialography and histopathology, in the specificities of sialography and ultrasonography, and in the accuracies of sialography and both ultrasonography and histopathology. The correlation coefficient (r) between sialography and ultrasonography was significantly higher than the others and indicated a good correlation. CONCLUSIONS Ultrasonography can be used as a diagnostic tool for SS, with its advantage of noninvasiveness and ease of use.

Analysis of adenoid cystic carcinoma treated by radiotherapy

The records of 41 patients with adenoid cystic carcinoma of the head and neck region who had been treated with radiotherapy were reviewed. Local control was achieved in 72.3% in the cases with primary lesions at 5 years. The prognosis for tumors that arose in the major salivary glands was better than that for tumors that arose in the minor salivary glands; however, the difference was not statistically significant. In the minor salivary glands, early-stage tumors were well controlled with the use of radiation therapy alone. In spite of the high local control rate, the disease-free survival rate of the patients at 10 years was only 20.8%. Lung metastasis determined the prognosis.

Relationship between sialographic findings of parotid glands and histopathologic finding of labial glands in Sjögren's syndrome: Relation to clinical and immunologic findings

We investigated a relationship between sialographic findings of parotid glands and histopathologic changes of labial glands, in relation to Sjögrens syndrome. We examined 107 patients, suspected to have Sjögrens syndrome because of dry mouth and dry eyes, in whom no other autoimmune diseases were diagnosed. Parotid sialography identified 37 patients with punctate, globular, cavitary, or destructive sialectasia (S-positive group). These sialographic findings were not seen in the other 70 patients (S-negative group). Among these patients, 54 demonstrated periductal lymphocytic infiltration in the labial glands (H-positive group), whereas the other 53 patients did not demonstrate this histologic finding (H-negative group). Significant differences in stimulated parotid salivary flow rate and incidence of keratoconjunctivitis sicca were observed between patients in the S-positive and the S-negative groups. Differences in the salivary flow rate and the incidence of keratoconjunctivitis sicca were also seen between patients in the H-positive and the H-negative groups, although the differences were not statistically significant. The rate of incidence of serum rheumatoid factor, anti-SS-A, and anti-SS-B antibodies were significantly higher in the S-positive and the H-positive groups than in their negative counterparts.

Scintigraphic evaluation of long-term salivary function after bilateral whole parotid gland irradiation in radiotherapy for head and neck tumour

In 25 patients with head and neck tumour, in whom bilateral whole parotid glands were totally included in the irradiation volume, parotid gland function was estimated and compared with that of 58 non-irradiated parotid glands in 29 patients, by symptomatic grading and radioisotope (RI) sialography. Sequential follow-up by RI sialography has suggested that if the total dose to the parotid gland is less than 52 Gy or if the time-dose fractionation (TDF) value is less than 80, then partial recovery of salivary function can be expected 1 or 2 years after irradiation, even if patients show severe xerostomia during the first 6 months. Long-term recovery rarely occurs in parotid glands which have been irradiated at doses exceeding 55 Gy or with TDF values of 88 or higher. The 50% complication probability (ED50) was less than 33 Gy for subacute xerostomia during the first 6 months and 52.5 Gy for chronic xerostomia after 12 months, respectively. Although a prospective study will be required for confirmation, differences between the dose-response curves of xerostomia at subacute and chronic phases suggest a basis in different biological mechanisms.

Experience of high-dose-rate brachytherapy for head and neck cancer treated by a customized intraoral mold technique

Radiotherapy of head and neck cancer has become more successful with the advances in treatment modalities and use of a multidisciplinary approach. Higher quality treatment and a team approach to radiotherapy have thus been required for head and neck cancer. This study presents the clinical experience of high-dose-rate (HDR) brachytherapy for head and neck cancer treated by a customized intraoral mold technique. Two patients are reported for whom we created dental prostheses as the radiation carriers for HDR brachytherapy of their head and neck cancers. HDR brachytherapy with the dental prostheses reported here was feasible and effective for eradicating the head and neck cancer. It has been demonstrated that HDR brachytherapy using a customized intraoral technique can be a treatment option for patients who are not candidates for surgery or external irradiation. It is strongly suggested that specialized dentists are needed who are familiar with not only the anatomy and function of the head and neck region but also radiotherapy. Dental radiologists should take responsibility for constructing irradiation prostheses. If they do, they have the potential to improve the quality of life of patients who undergo radiotherapy for head and neck cancer.

Three-dimensional small-volume irradiation for residual or recurrent nasopharyngeal carcinoma.

PURPOSE To minimize side effects and to achieve a high local control rate, three-dimensional (3D) small-volume irradiation was used for locally residual or recurrent nasopharyngeal carcinoma. METHODS AND MATERIALS Between July 1992 and March 1998, 18 tumors (12 residual and 6 local recurrent cases) were treated with 3D planned small-volume irradiation. The total dose (i.e., the dose of conventional radiotherapy plus that of the 3D irradiation) was 78.4 Gy (74.8-91.0 Gy) in its mean value for residual disease and 105.0 Gy (94.8-125 Gy) for recurrence. The mean value of the 90% isodose volume was 40.3 cc (8.0-94.0 cc). The mean follow-up period from the start of the boost or re-irradiation was 39 months. RESULTS The 3-year local control rate of the 12 residual tumors was 70%. Of 9 T4 residual tumors, 7 were controlled at a follow-up period between 17 and 70 months (median of 42 months). Of 6 recurrent tumors treated with re-irradiation, 3 were controlled at a follow-up period between 7 and 28 months. In the case of booster therapy, trismus occurred in 1 patient with a total dose of 91 Gy. Among the patients receiving re-irradiation, a temporary ulceration of the nasopharyngeal mucosa developed in 1 patient with a total dose of 111 Gy. CONCLUSION 3D small-volume irradiation was effective and safe in treating residual or recurrent nasopharyngeal carcinoma.