Tin Colloid Research Articles

The Use of Periareolar Intradermal Tc-99m Tin Colloid and Peritumoral Intraparenchymal Isosulfan Blue Dye Injections for Determination of the Sentinel Lymph Node

The purpose of the present study was to evaluate the use of lymphoscintigraphy, blue dye, and gamma probe detection methods for determination of the sentinel lymph node (SLN) using both periareolar intradermal injection of Tc-99m tin colloid and peritumoral intraparenchymal injection of isosulfan blue dye. One hundred patients with T1-2 breast cancer and clinically negative nodes were enrolled in the present study. The study was composed of 2 groups. Backup axillary lymph node dissection (ALND) was mandatory in group 1 (20 patients) regardless of their lymph node status. In group 2 (80 patients), complete ALND was performed when intraoperative frozen section analysis of SLN revealed metastases. Otherwise, only SLN biopsy was performed without ALND. One day before surgery, Tc-99m tin colloid was injected at 4 periareolar sites intradermally. Lymphoscintigraphy was performed 1 to 2 hours after injection of the radiocolloid. Twenty minutes before surgery, isosulfan blue dye was injected into parenchyma surrounding the tumor or the biopsy cavity. The detection rates of SLN and false-negative rate of lymphoscintigraphy, blue dye, and gamma probe detection were 85%, 95% 100%, and 0% in group 1, 91%, 87%, and 95% in group 2, respectively. Detection rate by the combination of blue dye and radio tracer was 98%. According to the results of our study, we conclude that perioareolar intradermal injection of Tc-99m tin colloid combined with peritumoral intraparenchymal injection of blue dye is an accurate and easy method of locating the sentinel node with very high detection rates. It is recommended that the combination of all methods such as lymphoscintigraphy, blue dye, and gamma probe application will increase the success rate of SLN detection in patients with breast cancer.

Dispensing and Administration of Radiopharmaceuticals for Dacryoscintigraphy

Dacryoscintigraphy was first introduced in 1972 as a method to detect and localize obstructions of lacrimal drainage under physiologic conditions.1 It has since become commonly used in the evaluation of epiphora.2–7 Briefly, about 50–100 μCi of Technetium Tc-99m sodium pertechnetate or Tc-99m sulfur colloid in a volume of about 10–15 μL is placed on the surface of the eye.3,5 The transport of the radioactive tracer from the conjunctiva into the lacrimal drainage system and flow through the drainage duct to the nasal cavity can then be followed through images obtained using a gamma camera. This radiopharmaceutical dose has customarily been administered onto the surface of the eye using a micropipette.2–6,8–12 Although feasible for administration, dispensing of the radioactive dose in this manner is problematic, especially related to issues of sterility and radioactive contamination. Using a micropipette necessarily requires withdrawal of the radiopharmaceutical solution from an open container into an unsealed pipette tip, which makes sterility difficult to maintain. Leakage of radiopharmaceutical solution from the unsealed pipette tip, resulting in radioactive contamination of the immediate surroundings, may be difficult to avoid. Because these sterility and radioactive contamination issues preclude transportation of the loaded micropipette, it must be filled with the radiopharmaceutical at the immediate location of use. Hence, dispensing (and administration) of the radiopharmaceutical dose in a closed, sterile apparatus taken from a sealed, sterile source would be desirable. The purpose of this study was to evaluate alternative devices for dispensing and administration of radiopharmaceuticals for dacryoscintigraphy.

Interim Results of Sentinel Node Biopsy during Laparoscopic Gastrectomy: Possible Role in Function‐Preserving Surgery for Early Cancer

Intraoperative detection of sentinel nodes (SNs) has been used clinically to predict regional lymph node (LN) metastasis in patients with breast cancer and malignant melanoma. Intraoperative lymphatic mapping and SN biopsy can potentially be combined with minimally invasive surgery. However, few reports have demonstrated the validity of SN biopsy during laparoscopic gastrectomy. The aim of this study was to investigate the feasibility and accuracy of laparoscopic lymphatic mapping in predicting LN status in patients with gastric cancer. A total of 35 patients with gastric cancer diagnosed preoperatively as T1, N0 were enrolled. Endoscopic injection of technetium-99m-radiolabeled tin colloid was completed 16 hours before surgery, and radioactive SNs were identified with a gamma probe intraoperatively. Isosulfan blue dye was injected endoscopically during the operation. Laparoscopy-assisted gastrectomy with LN dissection was performed. All resected LNs were evaluated by routine pathology examination. SNs were detected in 33 (94.3%) of 35 patients. The mean number of SNs was 3.9, and the diagnostic accuracy according to SN status was 97.0% (32/33), as one patient with a false-negative result was observed. The patient with the false-negative specimen was finally diagnosed as having advanced gastric cancer with invasion into the proper muscular layer and severe lymphatic vessel invasion, causing destruction of normal lymphatic flow by the tumor. Radio-guided SN mapping during laparoscopic gastrectomy is an accurate diagnostic tool for detecting lymph node metastasis in patients with early-stage gastric cancer. Validation of this method requires further studies on technical issues, including indications, tracers, methods of lymph node retrieval, and diagnostic modalities of metastasis.

Sentinel Node Biopsy Using Dye and Isotope Double Tracers in Early Gastric Cancer

The results of sentinel node (SN) biopsy have been improved by the use of dye and isotope double tracers in melanoma and breast cancer. However, the usefulness of this double tracer technique has not been determined in gastric cancer. The aim of this study was to investigate the possibility of improving SN biopsy results by using double tracers in gastric cancer. Sixty-four gastric adenocarcinoma patients preoperatively diagnosed as cT1N0, were enrolled in the study. (99m)Tc tin colloid was injected by preoperative endoscopy, and lymphoscintigraphy was performed prior to operation. After laparotomy, isosulfan blue was intraoperatively injected using an endoscope. Blue-stained or radioactive nodes were identified and defined as SNs. Gastrectomy with D2 lymphadenectomy was performed in all patients. All dissected lymph nodes were evaluated for metastasis by hematoxylin and eosin staining and immunohistochemistry. SN detection rates using dye, isotope, or both tracers were 95.3%, 84.4%, and 96.9%, respectively, and their corresponding sensitivities were 52.9%, 52.9%, and 70.6%. In the pT1 subset, the sensitivity of the double tracer was 87.5%; and in a subset of tumors with diameter <4.5 cm, this was also 87.5%. These findings confirm that SN biopsy results are improved by using double tracers in gastric cancer and suggest that SN biopsy is suitable in cases of small-sized early gastric cancer.

The influence of radioisotope vehicle on breast sentinel node detection

Aim To assess the relationship between carrier molecule size and time elapsing between marker injection and sentinel node(s) biopsy in patients with breast cancer. Material The study performed on 122 women, in whom the sentinel node(s) was identified according to the procedure described below. In Group I ( n = 72 patients), SN identification was done with radioisotope marker of 400–3000 nm molecule size (tin colloid). In Group II ( n = 50 patients) radioisotope marker of <100 nm molecule size (colloidal albumin) was used. Methods All the patients of both groups received the markers with a single-point, intradermal, periareolar injection. Four hours after the injection (Group I – surgery in the next day) or immediately before the surgery (in this same day) (Group II), stationary lymphoscintigraphy was performed. Results Mean numbers of sentinel nodes identified with the radioisotope method in Groups I and II were 1.22 and 1.48, respectively. The difference was statistically significant ( p < 0.01). Conclusions There is a relationship between the radioisotope marker molecule size and the injection-to-intra-operative evaluation time. Administration of small molecule size radioisotope marker several hours prior to the planned surgery appears to be the optimum procedure in this method of SN identification in patients with breast cancer.

Individualized surgery for early gastric cancer guided by sentinel node biopsy

We have reported that lymphatic mapping using indocyanine green (ICG) solution can be a good tool for identifying sentinel nodes (SNs) in gastric cancer. The purpose of this study was to evaluate individualized operations for gastric cancer guided by SN biopsy and to explore the possibility for more limited operative procedures using SN technology. SNs were identified by using (99m)Tc-labeled tin colloid and ICG solution in patients with clinically T1N0M0 gastric cancer. When pathologic examination by frozen section revealed metastasis in SNs, we performed a standard D2 gastrectomy. Less extensive lymphadenectomy preserving vagus and pylorus was applied when the SN biopsy was negative. Then, postoperative pathology was analyzed. Among the 80 enrolled patients, 7 patients with apparent node metastasis or T2-3 neoplasms and 10 patients with positive metastasis in SNs underwent D2 gastrectomy. Sixty-one patients with negative metastasis in SNs underwent a less extensive, function-preserving gastrectomy. The false-negative rate in sentinel node biopsy was 23% (3/13) for frozen section and 7% (1/14) for postoperative pathology. In 3 patients with a false-negative result, metastasis was found in lymph nodes located at the station where the tracers were distributed. Of the 7 patients in whom metastasis was detected in 2 or more SNs by frozen section, postoperative pathology revealed that 3 patients (43%) belonged to the N2 category. SN biopsy is a useful tool for individualizing the operative procedure for early gastric cancer. Dissecting the lymph node stations only where the tracers are distributed may be a promising procedure for patients with no metastatic SNs.

Colloid scintigraphy in non-alcoholic steatohepatitis: A conventional diagnostic method for an emerging disease

Non-alcoholic steatohepatitis (NASH) is a progressive liver disease characterized by diffuse fatty infiltration and Kupffer cell dysfunction which contributes to its pathogenesis. Since the liver biopsy, which is considered the 'gold standard' in diagnosing NASH, has some limitations other imaging methods have been explored as alternatives. Colloid scintigraphy is a good method reflecting Kupffer cell activity and we found it worthwhile to evaluate this technique in NASH. We aimed to present the common scintigraphic features and their clinicopathologic correlations in NASH. Twenty-two new patients (11 female, mean age 43.7+/-10.8) with biopsy-proven NASH underwent colloid liver scintigraphy. The dynamic, static and SPECT images were performed after intravenous injection of 185 MBq Tc tin colloid. Hepatic perfusion, blood pool clearance time, colloid shift to spleen and bone marrow were assessed and liver right/left lobe ratio was calculated. The values calculated on static and tomographic (SPECT) images showed good correlation. Liver right/left lobe ratio was altered in all patients. Blood pool clearance time was prolonged in seven (32%) but hepatic perfusion was normal in all patients. Colloid shift to the spleen was observed in 55% of patients using SPECT analysis. No correlation between scintigraphy parameters and histological or biochemical findings were observed. Altered liver right/left lobe ratio was the universal finding in all our NASH patients. Other common scintigraphic features of NASH include colloid shift to spleen and prolonged blood pool clearance time. Liver scintigraphy might be a promising non-invasive tool in the follow-up of NASH patients in therapeutic trials.

Sentinel Lymph Node Radiolocalization with 99mTc Filtered Tin Colloid in Clinically Node-Negative Squamous Cell Carcinomas of the Oral Cavity

The objective of this study was to evaluate the feasibility of sentinel lymph node biopsy by using a radiotracer lymphatic mapping technique in patients with squamous cell carcinoma of the oral cavity, and the diagnostic value of this technique. We studied twenty patients with previously untreated squamous cell carcinomas of the oral cavity and N0 necks. After the peritumoral injection of 99mTc filtered tin colloid preop-eratively, lymphoscintigraphy and intraoperative mapping using a gamma detector were performed to localize sentinel nodes. An open biopsy of the sentinel node was followed by complete neck dissection. We identified the sentinel nodes in 19 of 20 patients (95.0%) by lymphoscintigraphy and in all (100%) by intraoperative gamma detector. In all cases, the status of the sentinel node accurately predicted the pathologic status of the neck with the false negative rate being 0%. The negative predictive value for the absence of cervical metastases was 100%. In conclusion, our radio-localization technique of sentinel nodes using 99mTc filtered tin colloid in N0 squamous cell carcinomas of the oral cavity is technically feasible and appears to accurately predict the presence of the occult metastatic disease.

Effect of acute starvation on plasma fibronectin response to sepsis

There is evidence that undernutrition may contribute to the reduction in plasma fibronectin concentration and the depression of the reticuloendothelial (RE) system associated with severe sepsis. We have investigated the effects of fasting, surgical trauma and sepsis on plasma fibronectin concentrations and RE function. In experiment 1, plasma fibronectin was measured in rabbits (n = 14) before and 48 h after fasting. In experiment 2, sepsis was induced by devascularization of the appendix in animals on a normal diet (sepsis group, n = 7). A third group of animals underwent only a laparotomy (laparotomy only group, n = 7). Plasma fibronectin concentrations and the blood clearance and organ distribution of 99mtechnetium tin colloid (TTC) were measured 24 h after operation. Compared with pooled reference plasma, fasting in experiment 1 resulted in a reduction in mean(s.e.m.) plasma fibronectin concentration from 98(1.5) per cent to 86(3.7) per cent (T = 2, P less than 0.005). Mean(s.e.m.) plasma fibronectin concentration was raised in the sepsis group to 117(4.6) per cent, compared with 97(2.5) per cent in the laparotomy only group (U = 5, P less than 0.02), but there was no such increase in the fasting and sepsis group. There was a delay in the blood clearance and reduced hepatic uptake of TTC in both sepsis groups. The dissociation between fibronectin concentrations and RE function in animal models of sepsis casts doubt on the importance of fibronectin in RE function.

Reticuloendothelial failure in chronic intra-abdominal sepsis: the role of opsonic fibronectin.

Severe sepsis leads to depression of the reticuloendothelial (RE) system with delayed bloodstream clearance of particulate matter and bacteria. Fibronectin may be an important opsonin of the RE system and low fibronectin levels often accompany severe sepsis in man. We have investigated the effect of prolonged intra-abdominal sepsis on plasma fibronectin concentrations and RE function. Serial plasma fibronectin concentrations were determined in rabbits for 2 weeks after either the induction of sepsis (appendix abscess) (n = 6) or laparotomy only (n = 6). RE function was measured at 2 weeks by determining the clearance kinetics and organ distribution of low dose technetium tin colloid (TTC). There was an early transient depression in plasma fibronectin values followed by elevated concentrations at 48-72 h which were more marked in the sepsis group. There was a delay in the blood clearance with reduced hepatic and increased bone uptake of TTC. We conclude that depletion of opsonic fibronectin is unlikely to be an important factor contributing to the impairment of RE function associated with intra-abdominal sepsis and that RE depression in septic animals is due to intrinsic Kupffer cell dysfunction.

Increasing age does not affect efficacy of sentinel lymph node biopsy using smaller-sized technetium-99m tin colloids for breast cancer patients

Background Increasing age of breast cancer patients was reported to cause not only failure of sentinel lymph node (SLN) identification but also false negative results. Methods A retrospective review was conducted of breast cancer patients who underwent sentinel lymph node biopsy (SLNB) using small-sized technetium-99m–labeled tin colloid (particle size: 200–400 nm in diameter). A comparison between 82 patients who were less than 60 years and 40 patients who were ≥60 years of age was performed to evaluate the efficacy of SLNB using the small-sized tin colloid in older patients. Results One hundred twenty-two clinically node-negative breast cancer patients underwent SLNB. Apart from age, there were no statistically significant differences between the younger patients and the older patients in terms of the clinicopathologic characteristics. Successful mapping rates, false negative rates, and accuracy were comparable between the 2 groups. Conclusions SLNB using the small-sized tin colloid was not affected by increasing age.

Detection of sentinel nodes and micrometastases using radioisotope navigation and immunohistochemistry in patients with gastric cancer

Patients with early gastric cancer may be treated by minimally invasive surgery. This study investigated the value of sentinel node (SN) navigation surgery, including detection of micrometastases, in patients with clinical (c) T1 and T2 gastric cancer. The day before surgery (99m)Tc-radiolabelled tin colloid was injected submucosally near the tumour. After resecting the stomach, radioisotope uptake in all dissected lymph nodes was measured during and after surgery. Micrometastasis was detected immunohistochemically using an anticytokeratin antibody. SNs were identified in 99 of 104 patients. The rate of identification of SNs in patients with cT1 and cT2 tumours, excluding three technical failures, was 99 and 95 per cent respectively. Lymph node metastases and/or micrometastases were found in 28 patients (15 cT1 and 13 cT2). In the 15 patients with cT1 tumours, at least one SN contained metastasis and/or micrometastasis. For cT1 tumours, the sensitivity and accuracy of detecting SNs were both 100 per cent. Six patients with cT2 tumours had false-negative results. SN navigation surgery appears to be clinically useful only for cT1 tumours. Based on SN results, the extent of lymphadenectomy may be reduced in patients with early gastric cancer.

Laparoscopic Lymphatic Mapping and Sentinel Node Biopsies for Early‐stage Gastric Cancer: The Cause of False Negativity

Sentinel node (SN) biopsies might be useful for performing minimally invasive surgery without interrupting surgical curability. This study examined the cause of false negativity during laparoscopic lymphatic mapping and SN biopsies for early-stage gastric cancer. Thirty-seven patients with gastric cancer (preoperative stage T1-2 or N0) who underwent laparoscopic lymph node mapping and SN biopsies between March 2001 and June 2004 were enrolled in this study. The tracer, patent blue and technecium-99m-labeled tin colloid, was injected endoscopically. Blue-stained or radioactive nodes were defined as SNs. Gastrectomy with lymphadenectomy was performed then the results of the SN biopsies were compared with the final diagnosis of the removed lymph nodes in permanent sections. Sentinel nodes were successfully identified in 35 patients (94.6%), and they were positive in 3 of 4 patients with metastatic lymph nodes; sensitivity was 75% and specificity was 100%. Sentinel node status could therefore be used to diagnose lymph node status with 97.1% accuracy. Of 6 SNs with metastasis, 5 showed radioactivity, and only 2 were blue stained. In the false negative case, a radioactive SN with metastasis in the right paracardial region was missed during laparoscopic mapping. An error in laparoscopic intracorporeal detection of the radioactive node with metastasis occurred because we could not eliminate the shine-through effect. We found that during laparoscopic SN mapping there is a high risk of false negativity with SNs located in the right paracardial region. To apply laparoscopic SN mapping to early-stage gastric cancer patients, the shine-through effect must be eliminated because radiotracers are essential for this method.

口腔咽頭癌Ｎ０症例に対するセンチネルリンパ節―症例の総括と有用性，問題点―

We assessd the feasibility and problems associated with sentinel lymph node (SLN) study in 13 cases of oral and pharyngeal squamous cell carcinoma (SCC) that were neck-node-negative clinically. The primary sites were the tongue (n = 10), other sites in the oral cavity (n = 2), and the mesopharynx (n = 1). The day before surgery, tracer was injected into the submucosa around the tumor, and scintigraphic images were acquired 2 hours later. The SLN was identified intraoperatively with a handheld gamma probe, and neck dissection, including the SLNs, was performed. Radioactivity within the nodes was confirmed with a well type scintillation counter, and all resected lymph nodes were histologically examined for metastasis. The SLN was identified in every case. There were regional lymphnode metastases in 4 cases, and metastasis to the SLNs was present in all of 4 cases. Thus, the SLN concept was valid for head and neck SCC, sentinel node navigation surgery (SNNS) was thought to be applied in stage NO SCC of the head and neck. If SNNS is performed, about 70% of patients do not require neck dissection. SNNS is feasible and cost-effective in these cases. We used two different tracers: phytate and tin colloid, and found that phytate was more useful. To avoid the effects of the shine-through phenomenon, it was thought that some directions of lymphoscintigram should be taken. For intraoperative identification of the SLNs, care should be taken to the angle of gamma probe. SLN study leads to clarify each patient's lymphoid flow mapping, and it is also useful to determine the dissection area of selective neck dissection.

Prolonged gastric emptying half-time and gastric hypomotility after drug overdose

A prospective study was undertaken to determine if gastric motility and emptying are altered by the ingestion of overdoses of tricyclic antidepressants, acetaminophen, opioid-acetaminophen mixtures, carbamazepine or phenytoin. Gastric scintigraphy was used to measure gastric emptying half-time and assess gastric motility in 104 patients at initial presentation and again at follow-up (n = 85). Patients were imaged for 5 hours after being given 20 MBq of 99mTc tin colloid to drink. Drug serum levels were measured on all patients at initial presentation and at follow-up. We observed markedly prolonged gastric emptying half-times and severe hypomotility at initial presentation compared with follow-up in the vast majority of patients, except for a small group of patients with phenytoin poisoning. Twelve patients had gastric emptying half-times of over 300 minutes, a further 14 had half-times of over 200 minutes and 21 others had half-times of over 120 minutes. Poisoning is associated with hypomotility and a marked delay in gastric emptying that could influence the clinical course and patient management. These abnormalities may not be due to a direct effect of the ingested drug and factors such as stress may play a role.

Laparoscopically Assisted Total Gastrectomy with Sentinel Node Biopsy for Early Gastric Cancer: Preliminary Results

This study sought to describe a procedure involving laparoscopically assisted total gastrectomy (LATG) with sentinel node biopsy (SNB) and to evaluate the results of the first three patients. LATG for early gastric cancer was performed with sentinel node (SN) identification using a combined patent blue-violet dye and 99mtechnetium-labeled tin colloid technique. Laparoscopically resected SNs were processed for frozen section examination by routine hematoxylin and eosin (H&E) and immunohistochemical cytokeratin (IHC-CK) stains. LATG consists of a four-surgical port technique, removal of the specimen through a small 5-cm laparotomy, and stapled Roux-en-Y esophagojejunostomy. Five patients were candidates for LATG with SNB between March 2001 and June 2003; two had open surgery because of a tumor extending the serosal surface and peritoneal dissemination, whereas in the remaining three, SNs were successfully identified and evaluated with no evidence of sentinel node (micro) metastases intraoperatively. Based on the results of SNB, three patients underwent LATG with adequate lymphadenectomy. Mean operative time and blood loss were 375 min and 219 mL, respectively. No dissected lymph nodes had evidence of metastasis by H&E and IHC-CK on permanent sections. LATG with SNB followed by adequate lymphadenectomy is technically feasible, and with its acceptable operative time and blood loss, presents an excellent therapeutic option for early gastric cancer; while SNB and subsequent frozen section analysis by H&E and IHC-CK staining is a rapid and reliable diagnostic method for intraoperative detection of SN (micro) metastasis. This combination treatment is a promising alternative to laparoscopic gastrectomy with conventional lymphadenectomy.

Mesojejunal lymph node metastasis in esophageal cancer following total gastrectomy

We report on a case of thoracic esophageal cancer following total gastrectomy (rho-Roux-en-Y reconstruction) with metastasis to the mesojejunal lymph nodes. Subtotal esophagectomy with reconstruction using pedicled colon and dissection of two lymph node fields was performed. During the operation, we found three lymph nodes showing metastasis at the rho-Roux loop of the mesentery, and resected the rho-Roux loop. The route of the lymphatic drainage to the abdomen from the thoracic tumor seemed to have been changed by the prior gastrectomy. Based on the pathological findings, the case was diagnosed with T2N4M0, Stage IVa. We did not confirm that the distant metastases skipped the mesojejunal lymph nodes preoperatively; the distant metastases were detected accidentally by lymphoscintigraphy using technetium-99m tin colloid. We believe this case highlights the need for detailed examinations in esophageal cancer patients who have had prior gastrectomy.

Recent Development of Sentinel Lymph Node Biopsy for Breast Cancer in Japan

The number of breast cancer cases undergoing sentinel lymph node biopsy (SLNB) has been increasing with the number of articles published in Japan. SLNB using the dye method alone is performed in about one-third of patients. Analysis of questionnaire responses from 40 institutions in Japan revealed an identification rate by the dye method alone of 87%, compared with 96% using the combined method; the combined method is now recognized in Japan as superior to the dye method alone. No dyes have been specifically approved by the government for use in SLNB, and physicians have been using several inappropriate dyes as tracers for SLNB, such as indocyanine green, patent blue, indigo carmine, and isosulfan blue. The colloidal radiotracers used in Japan include tin colloid, stannous phytate, rhenium sulfate and human serum albumin. Albumin colloid and sulfur colloid are not commercially available in Japan. Small-size tin colloids, stannous phytate and rhenium sulfate all yield good results in terms of detection and false-negative rates. Provided that the surgeon has adequate experience in SLNB, a negative sentinel node can serve as a substitute for negative results from axillary lymph node dissection. Although many institutions have introduced SLNB, few reports have focused on the results of SLNB without axillary dissection because of short follow-up times and small number of patients. The final decision as to whether SLNB is an adequate substitute for axillary dissection awaits the results of prospective randomized trials.

Optimal particle size of radiocolloid for sentinel node identification in breast cancer — Electron microscopic study and clinical comparison

Sentinel node (SN) biopsy using a radiotracer is easy to learn, reproducible, and performed by the majority of breast cancer surgeons. However, this technique raises the question: what is the optimal particle size of colloid? Patients were injected with conventional tin colloid (median particle diameter: 700 nm) and the predominant particle size of radiocolloid retained in the SN was measured using electron microscopy. This showed a narrow distribution of colloidal size (100-150 nm). Patients were then injected with modified tin colloid having a median particle size of 100 nm. A clinical comparison was performed between conventional particle size or reduced particle size tin colloid and the SN biopsy success rate, the number of SNs, and the colloidal uptake in SNs. A total of 118 patients were injected with the conventional tin colloid (group I) and 124 patients with the smaller particle colloid (group II). The identification rate and the number of SN in both groups were almost equal, and the patients with low-uptake SNs were not significantly less in group I(p = 0.55). However, in the subgroup of patients 60 years of age or more, group II had significantly more SNs than group I(1.4 vs 1.9; p = 0.03) and low-uptake SNs were significantly less common than in group I(p = 0.02). The improvement of colloidal uptake in SNs using the smaller particle size tin colloid was confirmed, and this impact was statistically significant in the older population.

Lymphoscintigraphy for the visualization of sentinel lymph nodes and body contour

It is important to create clear lymphoscintigraphic images when assessing the sentinel lymph nodes. This clarity needs to reach a level where the sentinel lymph nodes (SLNs) and the body contour are clearly visible. We have developed a simple image processing method using the division of primary and scattered photon counts. Twenty patients with breast cancer were enrolled in this study. Manual injection of 150 MBq of Tc-99m tin colloid with small particle size into the peritumoral and subdermal regions was performed. Lymphoscintigraphy using a conventional gamma camera was performed three hours after the injection. Dual energy windows were set from 130 to 150 keV for the primary photons and 70 to 110 keV for the scattered photons. An anterior view of the chest and a lateral view from the affected side were obtained. Primary photon image counts were divided by the scattered photon image counts for each pixel after the addition of some constant counts to each pixel of the acquired image to improve the contrast of the scintigrams. We evaluated the ability to accurately visualize the body contour and the SLNs on the processed image. Image processing time was 20 to 40 seconds for each patient. In every case, the processed image clearly identified the body contour. The processed images allowed the identification of the same number of SLNs as the original images. This proposed method for image processing is a simple and useful means to clearly visualize both SLNs and body contours.