The utility of SPECT for 99mTc-MAA hepatic arterial perfusion scintigraphy

The utility of single-photon emission computed tomography (SPECT) for hepatic arterial perfusion scintigraphy was evaluated in 86 patients (91 studies). Previous reports have shown planar studies to be valuable for the clinical management of patients receiving intraarterial chemotherapy and more reliable than angiography in determining blood flow distribution. However, overlying areas of intra- and extrahepatic perfusion can sometimes make interpretation of these two-dimensional images difficult. Since SPECT has the potential to depict the three-dimensional distribution of perfusion, separate out overlying activity, and improve contrast resolution, SPECT Tc-MAA perfusion studies were compared to planar studies. Planar and SPECT studies both demonstrated the extent of hepatic and tumor perfusion, although occasionally SPECT added additional information. SPECT was most useful in confirming or excluding extrahepatic perfusion that was suspected but not definite on planar studies. Extrahepatic abdominal perfusion was found to be present in 11 (12%) of 91 studies. All patients with confirmed extrahepatic perfusion who received intraarterial chemotherapy had symptoms of drug toxicity compared to only a 23% incidence in those without evidence of extrahepatic perfusion (p less than 0.001). This report demonstrates that SPECT can improve the qualitative interpretation of hepatic arterial perfusion studies.     

Fusion imaging using a hybrid SPECT-CT camera improves port perfusion scintigraphy for control of hepatic arterial infusion of chemotherapy in colorectal cancer patients

Purpose Exclusive and homogeneous perfusion of the liver is considered essential for the efficacy of hepatic arterial infusion of chemotherapy (HAI). The aim of this study was to evaluate port perfusion scintigraphy in colorectal cancer patients using a hybrid SPECT-CT system for control of minimally invasive intra-arterial port systems within the scope of a phase II trial.Methods In 24 consecutive patients, the perfusion territories of intra-arterial hepatic port systems were assessed by port scintigraphy with ^99mTc-labelled macroaggregated albumin employing planar imaging, SPECT and SPECT-CT (acquired with a hybrid SPECT-CT camera). The results of blinded reading of the scintigraphic modalities concerning the intra- and extrahepatic perfusion pattern were compared with combined image analysis (angiography and contrast-enhanced dedicated CT) and patient history for validation.Results Extrahepatic perfusion was correctly seen in three patients, while suspected extrahepatic perfusion could be excluded in one. In 46 liver lobes, perfusion patterns were correctly visualised by SPECT-CT in 100% of cases (planar, 67%; SPECT, 86%). Assessing the perfusion pattern inside the liver on a segmental basis (segments, n=138), SPECT-CT revealed correct segmental assignment of tracer distribution in 100% and was significantly superior to SPECT alone (accuracy, 84%; p<0.001). The scintigraphic findings resulted in changes in therapeutic management in 8/24 patients (33%); in two of these the relevant findings were visualised only by SPECT-CT.Conclusion In patients receiving HAI, port perfusion scintigraphy by fusion imaging with a hybrid SPECT-CT system provides important information for therapy optimisation and appears to be superior to SPECT alone.     

Nuclear imaging in the identification of aberrant vascular anatomy prior to hepatic arterial infusion

Hepatic arterial infusion (HAI) pumps are a specialized therapeutic modality designed to deliver high dose local chemotherapy to hepatic metastases in carefully selected patients resulting in improved survival, with patients living an average of 2 years longer than those who did not receive HAI pumps. While beneficial, these chemoinfusion pumps require a multidisciplinary approach to ensure safe and effective treatment for the patient. Here, we present a case where scintigraphic evaluation by the nuclear medicine department directly affected management of a patient with a hepatic arterial infusion pump. Variant vascular anatomy was initially discovered on the postoperative Tc-99m MAA SPECT/CT and was ultimately embolized by interventional radiology prior to initiation of chemoinfusion. This case report demonstrates the utility of obtaining nuclear medicine scintigraphy prior to chemoinfusion in patients with hepatic arterial infusion pumps.     

Assessment of perfusion patterns during hepatic artery infusion chemotherapy: EOE-13 CT and 99mTc-MAA scintigraphy

Hepatic perfusion patterns were evaluated in five patients receiving hepatic artery infusion chemotherapy. All patients underwent 99mTc macroaggregated albumin (99mTc-MAA) scintigraphy and CT with EOE-13. In each case, the diagnostic agent was administered through the infusion catheter at 0.66 ml/min. Hepatic perfusion patterns were identified with both imaging methods, but CT with EOE-13 yielded more precise anatomic detail and was unique in demonstrating the perfusion status of each hepatic metastasis. Further evaluation of EOE-13 for this purpose is warranted.     

Comparison of Fusion Imaging Using a Combined SPECT/CT System and Intra-arterial CT: Assessment of Drug Distribution by an Implantable Port System in Patients Undergoing Hepatic Arterial Infusion Chemotherapy

Hepatic arterial infusion (HAI) chemotherapy is effective for treating primary and metastatic carcinoma of the liver. We compared the perfusion patterns of HAI chemotherapy on intra-arterial port-catheter computed tomography (iapc-CT) and fused images obtained with a combined single-photon emission computed tomography/computed tomography (SPECT/CT) system. We studied 28 patients with primary or metastatic carcinoma of the liver who bore an implantable HAI port system. All underwent abdominal SPECT using Tc-99m-MAA (185 Mbq); the injection rate was 1 mL/min, identical to the chemotherapy infusion rate, and 0.5 mL/sec for iapc-CT. Delivery was through an implantable port. We compared the intrahepatic perfusion (IHP) and extrahepatic perfusion (EHP) patterns of HAI chemotherapy on iapc-CT images and fused images obtained with a combined SPECT/CT system. In 23 of 28 patients (82%), IHP patterns on iapc-CT images and fused images were identical. In 5 of the 28 patients (18%), IHP on fusion images was different from IHP on iapc-CT images. EHP was seen on fused images in 12 of the 28 patients (43%) and on iapc-CT images in 8 patients (29%). In 17 patients (61%), upper gastrointestinal endoscopy revealed gastroduodenal mucosal lesions. EHP was revealed on fused images in 10 of these patients; 9 of them manifested gastroduodenal toxicity at the time of subsequent HAI chemotherapy. Fusion imaging using the combined SPECT/CT system reflects the actual distribution of the infused anticancer agent. This information is valuable not only for monitoring adequate drug distribution but also for avoiding potential extrahepatic complications.     

Single photon emission computed tomographic studies (SPECT) of hepatic arterial perfusion scintigraphy (HAPS) in patients with colorectal liver metastases: improved tumour targetting by microspheres with angiotensin II

As intra-arterial chemotherapy for liver metastases of colorectal origin becomes accepted, methods of further improving drug delivery to the tumour have been devised. Degradable microspheres have been shown to reduce regional blood flow by transient arteriolar capillary block, thereby improving uptake of a co-administered drug, when injected into the hepatic artery. In our study of five patients, we combined hepatic arterial perfusion scintigraphy (HAPS) and SPECT to assess the localization of approximately 1 X 10(5) labelled microspheres of human serum albumin (99Tcm MSA) in tumour. In addition, in three patients, we assessed the effect of an intra-arterial infusion of the vasoactive agent angiotension II during HAPS. Results were interpreted by comparing transaxial slices with corresponding slices of a tin colloid liver-spleen scan. Two of five patients showed good localization of 99Tcm MSA in tumour without an angiotensin II infusion. Of the three patients receiving angiotensin II, all showed good tumour targetting with the vasoconstrictor compared with only one of these three before its use. Thus, hepatic arterial infusion of angiotensin II greatly improves microsphere localization in tumour in some patients with colorectal liver metastases. This technique may be useful in the assessment of tumour targetting before and during locoregional therapy.     

Technetium-99m labelled macroaggregated albumin arterial catheter perfusion scintigraphy: prediction of gastrointestinal toxicity in hepatic arterial chemotherapy

Gastrointestinal toxicity from hepatic arterial infusion (HAI) of floxuridine in patients with liver metastases is probably due to extrahepatic perfusion or to partial escape of the drug from first-pass liver extraction. The aim of this study was to verify the role of technetium-99m-labelled macroaggregated albumin (99mTc-MAA) arterial catheter perfusion scintigraphy at the beginning of each chemotherapy cycle in decreasing or preventing gastrointestinal toxicity. We studied 167 consecutive patients. On the basis of the scintigraphic follow-up and the presence or absence of an intrahepatic arteriovenous shunt (IHAVS), we classified our patients into the following groups: (1) FU+ hepatic distribution pattern (DP), comprising 29 patients with regular scintigraphic follow-up who showed the expected distribution pattern at each control or a distribution pattern with transient alterations (extrahepatic escape) promptly reversed by the replacement of the catheter. Among these 29 patients there was one case of gastrointestinal toxicity. (2) FU- hepatic DP, comprising 128 patients who were evaluated with 99mTc-MAA only at the beginning of the first chemotherapy cycle, showed the expected distribution pattern and underwent HAI with no further scintigraphic evaluation. Among these 128 patients there were 28 cases of gastrointestinal toxicity. (3) FU+ pulmonary DP, comprising three patients with abnormally elevated pulmonary uptake (higher than 5%) and with regular scintigraphic follow-up. There were two cases of gastrointestinal toxicity among these three patients. (4) FU- pulmonary DP, comprising seven patients with abnormally elevated pulmonary uptake and without regular scintigraphic follow-up. There were four cases of gastrointestinal toxicity among these seven patients. The incidence of toxicity was significantly higher in group FU- hepatic DP than in group FU+ hepatic DP (21.9% vs 3.4%, P<0.05). In both the FU+ pulmonary DP and FU- pulmonary DP groups, the incidence of gastrointestinal toxicity was higher than 50%, with no significant difference between them. We conclude that, when performing 99mTc-MAA perfusion scintigraphy, the presence of an abnormally elevated pulmonary uptake (IHAVS higher than 5%) is the most relevant positive prognostic index for the development of gastrointestinal toxicity. Furthermore, in the absence of abnormal pulmonary uptake (IHAVS lower than 5%), strict scintigraphic follow-up is useful since it is able to promptly diagnose the presence of extrahepatic abdominal perfusion and thus to prevent the occurrence of gastrointestinal toxicity.     

Evaluation of Extrahepatic Perfusion of Anticancer Drugs in the Right Gastric Arterial Region on Fused Images Using Combined CT/SPECT: Is Extrahepatic Perfusion Predictive of Gastric Toxicity?

Background Hepatic arterial infusion (HAI) chemotherapy is effective for treating primary and metastatic carcinomas of the liver. Since hepatic arteries also supply the stomach and duodenum, HAI may result in unwanted infusion into the upper gastrointestinal tract and consequent gastric toxicity. Using fused images obtained with a combined SPECT/CT system, we assessed extrahepatic perfusion (EHP) and its correlation with gastrointestinal toxicity in patients receiving HAI. Methods We studied 41 patients with primary or metastatic carcinoma of the liver who received HAI chemotherapy consisting of 5-fluorouracil and cisplatin. All underwent abdominal SPECT using a ^99mTc-MAA (185 MBq) instrument and an injection rate of 0.1 ml/min, identical to the chemotherapy infusion rate. Delivery was through an implantable port. We analyzed the distribution of the anticancer agent on fused images and the relationship between EHP of the right gastric arterial region and gastric toxicity. All patients underwent esophagogastroduodenoscopy (EGDS). Results Of the 41 patients, 11 (27%) manifested enhancement of the duodenal and gastric pyloric region on fused images. EGDS at the time of reservoir placement detected gastric ulcers in 10 of these patients. Conclusion Fusion imaging with combined SPECT/CT reflects the actual distribution of the infused anticancer agents. The detection of EHP on fused images is predictive of the direct gastric toxicity from anticancer agents in patients undergoing HAI.     

Lung ventilation/perfusion SPECT in the artificially embolized pig.

Planar lung scintigraphy is a standard method used for the diagnosis of lung embolism, but it is hampered by the high incidence of nondiagnostic tests. Ventilation/perfusion SPECT may possibly improve this situation. The objective of this study was to compare planar lung scintigraphy with ventilation/perfusion SPECT using pigs with artificially engendered lung emboli labeled with (201)Tl. METHODS: Sixteen anesthetized pigs were each injected with zero to 4 latex emboli. Cylindric emboli were used in the first 7 pigs and flat 3-tailed emboli were used in the remaining 9 pigs. The pigs spontaneously inhaled 30 MBq (99m)Tc-diethylenetriaminepentaacetic acid aerosol for ventilation scintigraphy. Planar scintigraphy and SPECT were performed using a double-head gamma camera in (99m)Tc and (201)Tl windows. Immediately thereafter, 100 MBq (99m)Tc-labeled macroaggregated albumin were injected intravenously followed by SPECT and, finally, planar scintigraphy. The ventilation background was subtracted from the perfusion tomograms for calculation of a normalized ventilation/perfusion (V/P) quotient image set. RESULTS: The cylindric emboli caused artifacts in the ventilation images; therefore, these were excluded from the final analysis. However, for the planar perfusion images of these pigs, sensitivity and specificity were 71% and 91%, respectively, whereas SPECT yielded 100% for both. For the 3-tailed emboli and ventilation/perfusion images, the sensitivity and specificity were 64% and 79%, respectively, for the planar modality, whereas SPECT yielded values of 91% and 87%, respectively. CONCLUSION: V/P SPECT may improve the diagnostic power of lung scintigraphy.     

The predictive value of hepatic artery perfusion scintigraphy

A case in which hepatic artery perfusion scintigraphy (HAPS) correctly predicted the outcome of chemotherapy in a patient with metastatic liver disease is presented. In spite of angiography showing "proper" position of the Infusaid catheter, HAPS showed preferential perfusion to the right lobe of the liver. Computed tomography pre- and postchemotherapy showed a changing pattern of the metastatic foci correlating with the perfusion demonstrated by HAPS.     

肝断层及平面显像在肝占位性病变鉴别诊断中的意义──与B超、CT比较

本文对９２例临床可疑肝占位性病变患者进行了肝胶体及血池断层与平面显像，计算了肝血流灌注指数，并对照同期的病理及肝动脉造影资料，探讨了核素显像、ＣＴ及Ｂ超的诊断价值。研究表明，三种方法对肝癌及肝囊肿的诊断准确性无显著性差异（Ｐ＞０．０５），但断层显像对肝血管瘤的诊断（９３％）明显优于ＣＴ（８４％）和Ｂ超（８０％）；平面肝显像难以发现直径３ｃｍ以下的病变，对肝占位灶的检出率明显低于断层显像（Ｐ＜０．０５）。联合肝、胆道系统显像有助于降低假阳性率，其价值有待进一步探讨。     

Hepatic arterial perfusion scintigraphy with Tc-99m-MAA. Use of a totally implanted drug delivery system

Tc-99m-MAA hepatic arterial perfusion scintigraphy ( HAPS ) using a totally implanted drug delivery system was employed for hepatic arterial chemotherapy in 147 patients (335 studies). Complete perfusion of the involved liver was seen in 88% of patients initially [more so in those with normal hepatic vascular anatomy (93%) than those with vascular variants (79%)] and remained good on follow-up. In 67 consecutive patients (95 studies), arteriovenous shunting to the lung ranged from 0.4 to 32% (mean, 6.2% +/- 4.1 S.D.). Uptake at the tip of the catheter was increased in 20% of patients, but good perfusion was usually maintained. A significant decrease in hepatic and/or extrahepatic perfusion associated with a "hot spot" at the tip of the catheter indicated hepatic arterial thrombosis. Extrahepatic perfusion was seen in 14% of cases, usually in the distribution of the stomach, small bowel, and spleen. Significant symptoms of drug toxicity were seen in 70% of patients with extrahepatic perfusion, compared to 19% of those without it.     

Unsatisfactory hepatic perfusion after placement of an implanted pump and catheter system: angiographic correlation

Thirty-five patients with scintigrams showing unsatisfactory hepatic artery perfusion after surgical placement of an implanted pump and catheter system were examined with selective angiography (33 cases) or digital subtraction angiography (DSA) during which the contrast material was injected through the side port of the pump (six cases). In 34 of 35 cases, the cause of the unsatisfactory (either extrahepatic or incomplete) hepatic perfusion was defined. DSA was definitive in only two cases, in which extrahepatic flow through collateral vessels was demonstrated. The cause of the perfusion defect was hepatic artery thrombosis in 14 cases, extrahepatic flow through collateral vessels in 14 cases, a misplaced catheter in four cases, and a short proper hepatic artery without adequate length for mixing in two cases. Although hepatic artery perfusion scintigraphy is the primary tool for evaluation of hepatic perfusion after catheter placement, angiography plays an important role in treating the subset of patients with unsatisfactory hepatic perfusion.     

Optimal injection protocol for CT evaluation during hepatic arterial infusion chemotherapy

OBJECTIVE: As an imaging modality for follow-up during continuous or repeated hepatic arterial infusion chemotherapy using a hepatic intra-arterial indwelling catheter, the usefulness of CT while infusing contrast through the indwelling catheter (reservoir port) was examined. METHODS: Using reservoir ports implanted in eight patients with hepatic metastasis from colon cancer, radioisotope perfusion scintigraphy (RI), CT (three rates of infusion of contrast were used), and digital subtraction angiography (AG) were performed to compare the modalities' ability to visualize the intrahepatic and abnormal extrahepatic distributions. RESULTS: CT (infusion rate 0.1 mL/sec) was superior to AG and RI in terms of the ability to visualize intrahepatic distribution, particularly in small areas, and facilitated 3D delineation of the distribution. In evaluating extrahepatic distribution, CT also outperformed the other modalities. CONCLUSIONS: For imaging study follow-up during hepatic arterial infusion chemotherapy, CT proved to be more useful than conventional RI and AG.     

Intraarterial administration of EOE-13 for the CT evaluation of hepatic artery infusion chemotherapy

EOE-13 was infused directly into the hepatic artery through a surgically implanted hepatic artery infusion pump in a patient with liver metastases. A computed tomographic scan obtained after EOE-13 infusion accurately showed the perfusion pattern of the implanted catheter. It also demonstrated the hepatic metastases more clearly than scintigraphy with 99mTc-macroaggregated albumin. EOE-13 may prove useful for the evaluation of hepatic perfusion patterns in patients receiving hepatic artery infusion chemotherapy.     

Using slow-infusion MR arteriography and an implantable port system to assess drug distribution at hepatic arterial infusion chemotherapy

OBJECTIVE: The purpose of this study was to assess perfusion patterns seen on slow-infusion MR arteriography using the hepatic arterial infusion system compared with those seen on CT arteriography. SUBJECTS AND METHODS: In 37 patients with liver metastases who had implantable port systems for hepatic arterial infusion chemotherapy, slow-infusion MR arteriography using an infusion rate of 10 mL/hr through an implantable port and CT arteriography using an injection rate of 0.7 mL/sec were performed. In 15 of 37 patients, we evaluated enhancement patterns of tumors of the liver and visceral organs using slow-infusion MR arteriography. In all 37 patients, we compared slow-infusion MR arteriography with CT arteriography concerning intra- and extrahepatic perfusion patterns. RESULTS: On slow-infusion MR arteriography performed 10-20 min after initiation of infusion, tumors of the liver revealed significant enhancement with only a slight effect of systemic enhancement. In seven (19%) of 37 patients, intrahepatic distributions on slow-infusion MR arteriography differed from those on CT arteriography. In eight patients, the patterns of extrahepatic perfusion into the duodenum and the pancreas head differed on slow-infusion MR arteriography from those seen on CT arteriography. In addition, strong artifact caused by platinum coils in the gastroduodenal artery interfered with the evaluation of perfusion in the area around the coils on CT arteriography, whereas no imaging artifact was seen on slow-infusion MR arteriography. CONCLUSION: We believe that slow-infusion MR arteriography reflects the actual distribution of infused drugs more accurately than CT arteriography. When clinical complications occur during treatment, slow-infusion MR arteriography should be used to assess perfusion abnormalities.     

Technetium-99m labelled macroaggregated albumin arterial catheter perfusion scintigraphy: prediction of gastrointestinal toxicity in hepatic arterial chemotherapy

Gastrointestinal toxicity from hepatic arterial infusion (HAI) of floxuridine in patients with liver metastases is probably due to extrahepatic perfusion or to partial escape of the drug from first-pass liver extraction. The aim of this study wasto verify the role of technetium-99m-labelled macroaggregated albumin (^99mTc-MAA) arterial catheter perfusion scintigraphy at the beginning of each chemotherapy cycle in decreasing or preventing gastrointestinal toxicity. We studied 167 consecutive patients. On the basis of the scintigraphic follow-up and the presence or absence of an intrahepatic arteriovenous shunt (IHAVS), we classified our patients into the following groups: (1) FU+ hepatic distribution pattern (DP), comprising 29 patients with regular scintigraphic follow-up who showed the expected distribution pattern at each control or a distribution pattern with transient alterations (extrahepatic escape) promptly reversed by the replacement of the catheter. Among these 29 patients there was one case of gastrointestinal toxicity. (2) FU– hepatic DP, comprising 128 patients who were evaluated with ^99mTc-MAA only at the beginning of the first chemotherapy cycle, showed the expected distribution pattern and underwent HAI with no further scintigraphic evaluation. Among these 128 patients there were 28 cases of gastrointestinal toxicity. (3) FU+ pulmonary DP, comprising three patients with abnormally elevated pulmonary uptake (higher than 5%) and with regular scintigraphic follow-up. There were two cases of gastrointestinal toxicity among these three patients. (4) FU– pulmonary DP, comprising seven patients with abnormally elevated pulmonary uptake and without regular scintigraphic follow-up. There were four cases of gastrointestinal toxicity among these seven patients. The incidence of toxicity was significantly higher in group FU– hepatic DP than in group FU+ hepatic DP (21.9% vs 3.4%, P<0.05). In both the FU+ pulmonary DP and FU– pulmonary DP groups, the incidence of gastrointestinal toxicity was higher than 50%, with no significant difference between them. We conclude that, when performing ^99mTc-MAA perfusion scintigraphy, the presence of an abnormally elevated pulmonary uptake (IHAVS higher than 5%) is the most relevant positive prognostic index for the development of gastrointestinal toxicity. Furthermore, in the absence of abnormal pulmonary uptake (IHAVS lower than 5%), strict scintigraphic follow-up is useful since it is able to promptly diagnose the presence of extrahepatic abdominal perfusion and thus to prevent the occurrence of gastrointestinal toxicity. Received 27 December 1999 and in revised form 2 February 2000     

Variable patterns of technetium-99m MAA perfusion in the therapeutically embolized liver

Hepatic perfusion studies using 99mTc macroaggregate albumin (MAA) particles have been utilized to document arterial catheter position and flow distribution in patients who are to undergo hepatic arterial chemotherapy infusion (HAI). We have recently been treating nonresectable hepatic neoplasms with transcatheter hepatic arterial chemoembolization (HAE) followed by HAI. The MAA perfusion studies in these patients show variable patterns. For this reason, we have reviewed our recent experience with 15 patients who underwent 21 HAEs and HAIs. The arteriograms and the MAA perfusion studies were reviewed and correlated. Early (within 4 hr of embolization) perfusion studies revealed flow reversal, or MAA reflux into an undesirable location in 11 cases. Two selected follow-up scans in 24 hr revealed restoration of flow to the embolized lobe, confirming the proper position of the catheter for HAI. Knowledge of both the hepatic arterial anatomy, and of the specific embolization procedure will allow accurate interpretation of the MAA perfusion study. Initial flow reversal, or MAA reflux, should not be interpretated as a malpositioned catheter, but prompt reevaluation after a period of 24 hr to document restoration of antegrade flow is suggested.     

Application of single-photon emission computed tomography (SPECT) with99mTc-MAA in evaluation of perfusion patterns during hepatic infusion chemotherapy

In 6 patients receiving hepatic artery infusion chemotherapy for liver metastases, planar and single-photon emission computed tomography (SPECT) images of the abdomen were obtained after intravenous injection of 99mTc-phytate, and intra-catheter injection of 99mTc-MAA in the same geometrical settings. With this method, the three-dimensional intra- and extra-hepatic distribution of the agents during hepatic artery infusion chemotherapy can be evaluated.     

Evaluation of diagnostic abilities of Ga-SPECT for head and neck lesions

OBJECTIVE: Single-photon emission computed tomography (SPECT) using gallium (Ga) has been frequently used for diagnosing head and neck tumors in patients. Although the usefulness of Ga-SPECT is well known, the degree of the increase in diagnostic ability with Ga-SPECT for head and neck tumors has not been reported. We compared the ability of the planar images of Ga scintigraphy, SPECT images of Ga scintigraphy, and CT images to diagnose head and neck primary tumors and neck metastases. METHODS: The subjects of this study were 167 patients with malignant head/neck lesions. For Ga scintigraphy, Ga-67-citrate (74 MBq) was injected via a cubital vein. Planar and SPECT images were taken 72 h after the Ga-67-citrate injection. The rate of detection of the primary lesions was compared first between SPECT and planar images then between SPECT and CT images. The rate of detection for each stage of disease according to the TNM classification was also analyzed. RESULTS: The rate of detection of primary lesions was 50% with planar imaging and 69% with SPECT. And similarly, regarding the rate of detection of lymph node metastases, there was a significant difference between planar imaging and SPECT. The rate of detection of primary lesions was 70% for both CT and SPECT. At T stage, the rates of detection of primary lesions with each imaging technique were 11% with planar imaging and 39% with SPECT, and 22% with CT for stage T1. CONCLUSIONS: This study revealed the marked superiority of SPECT images over planar images in terms of the ability to detect primary tumors and tumor metastasis to cervical lymph nodes. Furthermore, the primary T1 tumor detection rate of SPECT images was higher than that of CT images. On the basis of these results, the concomitant use of SPECT is highly recommended when Ga scintigraphy is performed to check for malignant head/neck tumors.