image fusion software can derive a fusion image from single photon emission computed tomography ( spect ) and computed tomography ( ct ) scans [ 1 , 2 , 3 , 4 , 5 ] . the fusion method has the advantage of being cost - effective without the need of special equipment , compared to the spect / ct system , which is a hybrid imaging method consisting of a spect camera and a ct scanner combined in a single device . since 2003 , fusion images have been used to detect sentinel lymph nodes ( slns ) in patients with skin cancer including melanoma , head and neck cancer , vulvar   and prostate   cancer , and especially cancer in areas with multiple and varied lymphatic drainage patterns or slns adjacent to the primary lesion . here , we report the use of three - dimensional ( 3d ) fusion images of slns in 3 patients with malignant melanomas in the lumbar , vulvar and head region , respectively . a 65-year - old woman was referred to our hospital for the examination of a black , partially erosive nodule that had existed for more than 5 years on her median lower back . multi - detector computed tomography ( mdct ; light speed 32 ; ge healthcare japan , tokyo , japan ) and positron emission tomography indicated that there were no metastases of the lymph nodes or other organs . one day before the operation , the patient underwent a pre - operative lymphoscintigraphy to identify the site of the sln . a dose of 0.2 ml 14.8 mbq tc-99 m phytate was injected intradermally at 4 points around the lesion . a dual - head gamma camera ( brightview ; hitachi medical corporation / philips , tokyo , japan ) produced static images at 15 min and at 2 h after injection . the right inguinal basin was shown to contain a hot node . using an image fusion software ( syntegra ; pinnacle ; adac , milpitas , calif . , usa ) , the fusion images were produced based on spect and mdct scans after the delayed planar images . to adjust the alignment of both images correctly , we overlapped the navel site on the spect and mdct scans . in order to accurately determine the location of the regional hot lymph node , we composed the fusion image in 3 views  transaxial , sagittal and coronal slices  using an ordered - subset expectation maximization algorithm ( astonish ; philips ; fig . it was located anterointernally to the femoral artery and vein at the height of the pubic symphysis . patent blue dye was injected at the tumor site just before the operation . the blue dye and the hand - held gamma probe techniques were used in combination during the intraoperative sln mapping . we detected the node at the expected site , as indicated by the 3d fusion image . a 41-year - old woman presented with an 8-month history of a black nodule on the left labium majus . the signal intensity was hotter in the left than in the right inguinal basin . during the operation , 2 lymph nodes in the left and 1 in the right inguinal basin were confirmed as slns . each node was harvested from the expected site , as indicated by the 3d fusion images . a 28-year - old man presented with a 10-year history of a black macule on the right parietal region of his head . three months before the first visit to our hospital , a nodule in the macule was noticed . 3 ) in the same manner as described in case 1 . to adjust the alignment , 3 markers ( capsules with about 7.4 mbq tc-99 m pertechnetate ) were fixed on the glabella , the mentum and the left porus acusticus . two hot nodes were present in the parotid region . during the operation , 2 slns were detected . a 65-year - old woman was referred to our hospital for the examination of a black , partially erosive nodule that had existed for more than 5 years on her median lower back . multi - detector computed tomography ( mdct ; light speed 32 ; ge healthcare japan , tokyo , japan ) and positron emission tomography indicated that there were no metastases of the lymph nodes or other organs . one day before the operation , the patient underwent a pre - operative lymphoscintigraphy to identify the site of the sln . a dose of 0.2 ml 14.8 mbq tc-99 m phytate was injected intradermally at 4 points around the lesion . a dual - head gamma camera ( brightview ; hitachi medical corporation / philips , tokyo , japan ) produced static images at 15 min and at 2 h after injection . the right inguinal basin was shown to contain a hot node . using an image fusion software ( syntegra ; pinnacle ; adac , milpitas , calif . , usa ) , the fusion images were produced based on spect and mdct scans after the delayed planar images . to adjust the alignment of both images correctly , we overlapped the navel site on the spect and mdct scans . in order to accurately determine the location of the regional hot lymph node , we composed the fusion image in 3 views  transaxial , sagittal and coronal slices  using an ordered - subset expectation maximization algorithm ( astonish ; philips ; fig . it was located anterointernally to the femoral artery and vein at the height of the pubic symphysis . patent blue dye was injected at the tumor site just before the operation . the blue dye and the hand - held gamma probe techniques were used in combination during the intraoperative sln mapping . we detected the node at the expected site , as indicated by the 3d fusion image . a 41-year - old woman presented with an 8-month history of a black nodule on the left labium majus . the signal intensity was hotter in the left than in the right inguinal basin . during the operation , 2 lymph nodes in the left and 1 in the right inguinal basin were confirmed as slns . each node was harvested from the expected site , as indicated by the 3d fusion images . a 28-year - old man presented with a 10-year history of a black macule on the right parietal region of his head . three months before the first visit to our hospital , a nodule in the macule was noticed . 3 ) in the same manner as described in case 1 . to adjust the alignment , 3 markers ( capsules with about 7.4 mbq tc-99 m pertechnetate ) were fixed on the glabella , the mentum and the left porus acusticus . two hot nodes were present in the parotid region . during the operation , 2 slns were detected . the spect / ct system is reportedly useful for sln biopsy [ 6 , 7 , 8 , 9 , 10 ] . spect detects gamma rays and produces the data of radioactive distribution in a 3d format , while ct illustrates the anatomical details of a body . wagner et al .   reported significant differences ( p = 0.0015 ) between the blue dye method only and the spect / ct method in detecting the number of slns in the neck area . van der ploeg et al .   stated that the detailed anatomical information obtained from spect / ct was particularly helpful in patients with a melanoma in the head and neck . they also showed that in 30 of the 85 ( 35% ) patients studied , there were clear advantages of using the spect / ct system over conventional planar lymphoscintigraphy , which resulted in the surgeons altering their incisions . in 2003 , kretschmer et al .   introduced the fusion of spect and pelvic ct scans of patients with malignant melanoma of the leg or the lower part of the body . they stated that the fusion image was an excellent tool to determine the exact location of pelvic slns . in 2005 , kizu et al . they also concluded that fusion images are useful in precisely locating slns . while kizu et al . recognized the usefulness of the spect / ct system for sln mapping , they also discussed drawbacks of the system : it is expensive and requires extra space for installation . they reported that such drawbacks are not specific to the fusion of spect and ct images . in our patients , the 3d fusion technique provided such concrete images of sln locations in the inguinal and head / neck basin that the surgeons could precisely perform an sln biopsy . another benefit of the 3d fusion images was that the patients , their families and the medical staff could understand the schematic information of the sln sites more easily . taking into account the reproducibility of patient positioning , the fusion technique seems to be well suited especially for patients with melanomas arising from the trunk or head , since marking spots adjust for the positional error . thus , we conclude that 3d image fusion was confirmed as a simple and helpful method for precisely localizing slns in these patients .
image fusion software can derive a fusion image from single photon emission computed tomography and computed tomography scans . 
 we applied a three - dimensional fusion image to detect sentinel lymph nodes ( slns ) in 3 patients with malignant melanomas of the lumbar , vulvar and head region , respectively . during each operation 
 , we detected slns at the expected site , as indicated by the fusion images . 
 the three - dimensional image fusion could thus be confirmed as a simple and helpful method for precisely localizing slns in these patients .