Shozo Hashimoto

A practical method for position-dependent Compton-scatter correction in single photon emission CT

A new method is proposed to subtract the count of scattered photons from that acquired with a photopeak window at each pixel in each planar image of single-photon emission computed tomography (SPECT). The subtraction is carried out using two sets of data: one set is acquired with a main window centered at photopeak energy and the other is acquired with two subwindows on both sides of the main window. The scattered photons included in the main window are estimated from the counts acquired with the subwindows and then they are subtracted from the count acquired with the main windows. Since the subtraction is performed at each pixel in each planar image, the proposed method has the potential to be more precise than conventional methods. For three different activity distributions in cylinder phantoms, simulation tests gave good agreement between the activity distributions reconstructed from unscattered photons and those from the corrected data.

Prognostic factors influencing relapse of squamous cell carcinoma of the maxillary sinus

In 95 surgically staged patients with squamous cell carcinoma of the maxillary sinus, multivariate regression analyses were employed to identify prognostic factors. Possible prognostic factors for local control were TNM stage and type of surgical procedures: T2 or T3 tumors and use of total maxillectomy showed better local control rates (P < 0.01). High radiation doses of 40 Gy or more also seemed to be of prognostic significance: P < 0.2 for 40 to 60 Gy, and P < 0.1 for 60 Gy or more. The risk of cervical relapse increased when the cheek or alveolus was grossly involved (P < 0.2). However, since cervical relapse frequently accompanied uncontrollable primary recurrence or distant spread, and since cervical relapse alone was frequently salvaged by radical neck dissection, prophylactic irradiation to the neck is not recommended. Sex, age, nodal state, addition of chemotherapy, total doses of bleomycin or 5‐fluorouracil (5‐FU), or intra‐arterial administration of chemotherapeutic agents did not appear to be of prognostic significance.

Computed tomography of malignant tumors of the nasal cavity and paranasal sinuses

Staging of malignant tumors of the nasal cavity and paranasal sinuses by computed tomography (CT) was studied in a total of 49 patients, 33 with squamous cell carcinoma and 16 with tumors of other histologic types. Involved sites by the tumor were studied, and clinical staging was made using CT findings alone according to AJC classification for maxillary sinus tumors. Surgical findings for comparison were available for most cases. Of 33 squamous cell carcinomas and of 16 tumors with other histologic types, the maxillary sinus was the site of origin in 29 and eight, respectively. Of these 37 maxillary sinus tumors, 11 were staged T3, 26 T4, and none was staged T1 or T2. None of these tumors were down staged, and one T3 was upstaged after surgical procedures, although all sinuses were not explored in some cases. Sinusitis due to obstruction was indistinguishable from the tumor without bone destruction. And the determination of the site of origin was difficult in some cases. Despite these, CT should be used for pretreatment evaluation of the tumors of these sites.

Phase II randomized clinical trial of LC9018 concurrently used with radiation in the treatment of carcinoma of the uterine cervix. Its effect on tumor reduction and histology

The clinical efficacy of LC9018, a biological response modifier prepared from heat‐killed Lactobacillus casei YIT9018, used in combination with radiation was studied in a randomized controlled trial on 61 patients with carcinoma of the uterine cervix of Stage IIB or III. The combination therapy with LC9018 demonstrated a significant effect on tumor reduction, compared with radiation therapy alone, at the cumulative doses of 15‐Gy and 30‐Gy external irradiation (P < 0.05). Histologic study confirmed that LC9018 also enhanced the therapeutic effect of the irradiation. Moreover, LC9018 seemed to be useful in protecting the patients from leukopenia during radiotherapy. This study suggests that LC9018, when used in combination with radiotherapy, will be an effective adjuvant immunotherapeutic agent. More studies in a large series of patients will, however, be needed to establish its long‐term efficacy, safety, and effects on both prognosis and enhancing radiotherapy.

Squamous cell Carcinoma of the Nasopharynx

Seventy-seven patients with nasopharyngeal squamous cell carcinoma were treated with irradiation, with or without chemotherapy. Sixty-three (82%) developed a relapse in some part of the body; the first relapse appeared at primary, cervical and distant sites in 45 (71%), 30 (48%) and 12 (19%) of the 63 relapsing patients, respectively. In 22 of the 63 relapsing patients, the first relapse occurred simultaneously in two or more sites. Local recurrence-free survival was higher for the T1 + T2 group than for the T3 + T4 group (p less than 0.02). Cervical relapse-free survival was higher for N0 patients than for N+ patients (p less than 0.02). Distant metastases frequently developed as a component of the first relapse. Distant metastases were more common in N+ patients than in N0 patients. Forty-two patients received adjuvant chemotherapy. Although local recurrence-free survival tended to be higher in patients with chemotherapy than without chemotherapy, survival rates and relapse-free survival rates did not differ in the two groups.

Improved survival of patients with nasopharyngeal squamous cell carcinoma

One hundred and one patients with nasopharyngeal squamous cell carcinoma (NPC) were treated with irradiation. The UICC TNM staging system (1978) was used: 6 patients were T1N0, 10 T2N0, 5 T3N0, 13 T4N0, 11 T1N+, 18 T2N+, 19 T3N+ and 19 T4N+. Since 1978, 34 patients were examined with computed tomography (CT) at first presentation. Fourteen (41%) of the 34 tumors were upstaged based on the CT findings alone. The technique of radiation therapy was markedly changed around 1978. The fields to the primary site and neck were enlarged. Two-year relapse-free survival was significantly better for the post-CT era than pre-CT era. This was mainly because of improved local-recurrence-free survival, and cervical-relapse-free survival. Improved local-recurrence-free survival, however, was appreciated in only T3 + T4 patients; there was no difference in T1 + T2 patients. It is suggested that merely enlarging radiation fields or increasing radiation doses could not be curative for some subpopulations. In order to increase local control rates further, we have started to use intracavitary irradiation with an after-loading technique as a boost. Preliminary results are encouraging.

Indium-111-labelled liposomes: dosimetry and tumour detection in patients with cancer

Neutral phospholipid vesicles (VesCan), which had been prepared for clinical use, were loaded with 37 MBq indium-111 and administered to seven patients with malignant tumours. The median lipid dose was 2.0 mg/kg. Sequential images showed rapid blood clearance at the early stage, with homogeneous uptake of 111In-labelled VesCan (111In-labelled V-liposomes) in the liver and spleen. Dosimetric estimates for these organs were 1.2 and 1.5 mGy/MBq, respectively, with a whole-body exposure dose of 0.076 mGy/MBq. Total renal excretion of 111In was less than 10% of the injected dose, occurring mainly as 111In-EDTA in three patients. Gamma camera images 24–48 h after administration revealed increased activity in the tumours of four patients. 111In-labelled V-liposomes may enable the demonstration of the tumour site without toxicity and with radiation doses comparable to other radionuclide imaging techniques.

The behavior of99mTc-hexamethylpropyleneamineoxime (99mTc-HMPAO) in blood and brain

Abstract99mTc-hexamethylpropyleneamineoxime (99mTc-HMPAO) is a reagent for scanning cerebral blood flow. We investigated how99mTc-HMPAO changed in the blood and brain. The99mTc-HMPAO, which was prepared by adding of99mTcO-4 to HMPAO and Sn(II), consisted of primary and secondary complexes, reduced hydrolyzed99mTc, and99mTc0pertechnetate. The percentage of the primary complex in99mTc-HMPAO decreased with time after preparation. The primary complex converted to the secondary one very rapidly in the presence of plasma. When99mTc-HMPAO was injected into patients,99mTc activity was immediately partitioned in the plasma fraction, with approximately 60% in whole blood. In plasma,99mTc was found to be associated with proteins such as albumin and globulin.99mTc trapped in red cells was not washed out with either plasma or saline. Biodistribution studies showed that the less lipophilic compounds of99mTc-HMPAO could not pass through the blood brain barrier (BBB), and therefore did not accumulate in the brain. The results of gel chromatography and equilibrium dialysis indicated that no specific99mTc binding protein was present in the brain. Considering the instability of99mTc-HMPAO in vivo, we proposed that the speed at which the primary complex converted to the less lipophilic compounds was important in allowing99mTc-HMPAO to pass through the BBB and to be fixed in the brain.

Phagocytosis of bacterial magnetite by leucocytes

SummaryMagnetotactic bacteria were introduced into granulocytes and monocytes by phagocytosis. The number of phagocytes containing bacterial magnetites (magneto-sensitive cells) became constant after 1.5 h incubation, and viable phagocytes contained about 20–40 cells of magnetotactic bacteria. Granulocytes and monocytes containing bacterial magnetites were separated by magnet a Samarium-cobalt from lymphocytes. After separation, 89% of lymphocytes were recovered and 95% of the cells were viable. The contamination of phagocytes in the recovered lymphocytes was below 0.8%. Magneto-sensitive granulocytes and monocytes were removed by applying a magnetic field. The nitro-blue tetrazolium-reducing, chemotactic and phagocytic abilities of phagocytes ingesting magnetotactic bacteria were 84%, 88% and 87% respectively after 1 h incubation.

Conversion of T-stages of nasopharyngeal carcinoma by computed tomography

Thirty-six patients with nasopharyngeal carcinoma (NPC) were examined with computed tomography (CT) before definitive radiation therapy. CT clearly delineated the extent of the primary tumors. CT frequently showed subtle destruction of the paranasal sinuses and pterygoid plate, which was not usually detected by conventional X ray examinations. T-staging was made according to the UICC TNM classification system (1978) or another system, depending on clinical findings and the conventional X ray examinations (non-CT T-stage). Then, the non-CT T-stage of each patient was compared with T-stage diagnosed with CT findings alone (CT T-stage). CT upstaged non-CT T-stage in 14 of the 36 patients according to either system. Only one patient was downstaged by CT; this patient had cranial nerve palsy but not detectable bone destruction as shown by CT. We conclude that CT is the single, most reliable imaging method for primary tumors of NPC patients. Since CT detects subtle bone destruction, however, a large number of patients will be classified as having advanced tumors. Further modification of the TNM system may be needed for NPC patients in this era of CT.