Lymphoscintigraphy of melanoma: lymphatic channel activity guides localization of sentinel lymph nodes, and gamma camera imaging/counting confirms presence of radiotracer in excised nodes.

UNLABELLED: Lymphoscintigraphy has become a standard preoperative procedure to map the cutaneous lymphatic channel for progression of nodal metastasis of melanoma of the skin. Lymphoscintigraphy was employed to visualize lymphatic channels as a guide to identify sentinel lymph nodes (SLNs). Excised tissue was imaged with a gamma camera to verify the findings of presurgical lymphoscintigraphy. Percent counts of SLN(s) among the total counts of the excised melanoma tumor or scar tissue and SLN(s) were calculated. METHODS: Eleven patients with cutaneous melanoma received four to ten intradermal injections of Tc-99m sulfur colloid at elual distances around the melanoma site. Images were made immediately after injection: 1 minute per image for 15 min; and then 5 minutes or 1,000,000 counts per image for 30 min. After surgery, the excised melanoma tumor or scar and SLN(s) were imaged/counted with a gamma camera. Percent counts of SLNs among the total counts of the excised melanoma tumor or scar tissue and SLNs were calculated. To validate the specimen count accuracy, an experimental phantom study was done. RESULTS: Linear lymphatic channels were identified between the injected sites and the SLNs in each patient. Gamma camera images demonstrated radioactivity in the SLNs of all patients, verifying the lymphoscintigraphy findings. Uptake in the SLNs of ten of the eleven patients ranged from 0.4 to 7.2% (mean 2.2%) of the total counts in excised tissue. We noted that a node with lower uptake should not be ignored because a lower percent of SLN activity does not necessarily rule out existing metastasis. In two of eleven patients, histopathologic showed metastases. One patient's melanoma on the middle back had lymphatic channel activity directed to both axillae. The results of the phantom study validated accuracy of our specimen counts. CONCLUSIONS: Because linear lymphatic channels existed between lymph nodes and the injected sites in all eleven patients, these lymphatic channels could be used as a guide for localizing SLNs. The SLNs indicated by presurgical lymphoscintigraphy were verified by postoperative gamma camera imaging, and radiotracer localization in the SLNs averaged 2.2%.

Tc-99m MIBI thoracic SPECT for the detection of intrathoracic tumor masses.

Thirty-one men (age range, 46-76 years; mean age, 64.8 years) with intrathoracic masses suggesting possible malignancy on the basis of chest radiography or CT underwent preoperative Tc-99m MIBI SPECT examinations. Diagnosis was confirmed on pathologic examinations of samples obtained either at thoracotomy, esophagectomy, or by biopsy. Twenty-five patients had primary lung cancer, including squamous cell carcinoma, large cell carcinoma, adenocarcinoma, and small cell carcinoma. Two patients had lymphomas with spread to the mediastinum, and three patients had extrathoracic primary cancers (one squamous cell carcinoma of esophagus, one squamous cell carcinoma originating from a head and neck tumor, and one metastatic mediastinal leiomyosarcoma). One patient with a tuberculoma had negative results of the Tc-99m MIBI examination. Tc-99m MIBI had a 86.7% sensitivity rate, a 0% false-positive rate, and a 100% positive predictive value to detect malignant intrathoracic masses. There was a 13% false-negative rate, however, suggesting that MIBI-SPECT may underdiagnose malignant lesions. SPECT findings of these 31 patients can be classified as 1) mass with increased uptake, n = 23; 2) ring-like appearance of increased uptake, n = 3; 3) mass with absent uptake, n = 4; and 4) photon-deficient mass, n = 1. Absent uptake in patients with mass lesions could be explained by necrosis of the lesion (caseation necrosis or massive tumor necrosis with or without bleeding). Most malignant intrathoracic masses are Tc-99m MIBI avid and may be detected with a high degree of sensitivity and with an excellent positive predictive value. A positive MIBI scan may help in the clinical diagnosis of malignancy. The use of Tc-99m MIBI could serve not only as a tumor imaging agent, but also may be used to determine the extent of spread and potentially the chemotherapeutic responsiveness of a tumor.

Detecting strontium-89 removable contamination using a sodium iodide well counter.

UNLABELLED: Monitoring for 89Sr removable contamination is required for incoming DOT-labeled packages and work areas containing radioactivity. However, few nuclear medicine departments are equipped for liquid scintillation counting, which is the preferred method for detecting beta emitters. We investigated using a sodium iodide well counter to detect 89Sr through its bremsstrahlung photon production. METHODS: We used a manufacturer's 89Sr-chloride solution of known concentration and tested various parameters: type of tube, access of tube contents to air, volume of sample, type of wipe material and counting geometry. Liquid scintillation samples also were obtained. RESULTS: Initial counting efficiencies were 0.10-0.14 cpm/dpm for small volume (10-microliter) samples. The various parameters tested had either positive or negative effects on the system's efficiency to detect 89Sr. One set of samples, counted over time, demonstrated a calculated mean half-life of 50.8 days, which is similar to the 89Sr reported half-life of 50.5 days. Liquid scintillation samples demonstrated efficiencies of almost 1.0 cpm/dpm and a calculated mean half-life of 50.8 days, both as expected. CONCLUSION: This study demonstrates that 89Sr removable contamination can be detected sensitively using a sodium iodide well counter, but special considerations must be made when determining the system's counting efficiency.

Communication between peritoneal cavity and mediastinal lymph nodes demonstrated by Tc-99m albumin nanocolloid intraperitoneal injection.

Lymphatic drainage from the peritoneal cavity to mediastinal lymph nodes has been reported, indicating that abdominal fluid is not immobile. We studied this movement in rats receiving Tc-99m albumin nanocolloid which has smaller particle sizes than does Tc-99m microaggregated albumin colloid used for liver/spleen imaging. The Tc-99m albumin nanocolloid had a radiochemical purity of 99.33%-99.77% with free pertechnetate of 0.23%-0.67%. During pentobarbital anesthesia, thoracoabdominal images were obtained 4-6 hr after intraperitoneal injection of 350 mCi Tc-99m albumin nanocolloid with 5 ml of normal saline. The images showed symmetrical radiotracer localization in the mediastinal lymph nodes. Scintigraphic demonstration of drainage to the mediastinal region from the peritoneal cavity may be explained by flow directly into mediastinum through the lymphatic system, indicating lymphatic patency between the peritoneal cavity and mediastinum. Absence of visualization may indicate lymphatic block. This type of information concerning lymphatic drainage may have clinical impact for a patient with malignant or intractable ascites. The radionuclide technique is easily performed for this assessment.

Lung uptake of Tc-99m HMPAO in cigarette smokers expressed by lung/liver activity ratio.

Tc-99m HMPAO, a lipophilic radiopharmaceutical used for brain imaging, has been reported to localize in smokers' lungs. To quantitate this uptake in the lung, 55 patients, who were referred for brain imaging for dementias or strokes, also underwent lung imaging (anterior lung imaging includes a large part of the liver) after IV injection of the radiopharmaceutical. Regions of interest over the liver and the lung were calculated. Of the 55 patients (ages 13-79), 30 were smokers and 25 were nonsmokers. The smokers had been smoking from 6-59 years, and daily cigarette consumption ranged from 8-50 cigarettes. The mean lung/liver ratio for smoking patients were 0.792 +/- 0.042 (SE); the mean lung/liver ratio for nonsmoking patients was 0.408 +/- 0.019 (SE). Lung/liver ratio uptake was significantly higher in the smoking patients (P < 0.01) than in the nonsmokers. Thus, lung/liver uptake of Tc-99m HMPAO may be used as an indicator of cigarette smoking.

[123I]HIPDM pulmonary imaging demonstrates elastase-induced pulmonary emphysema.

Because more than 90 percent of [123I]hydroxyiodobenzyl-propanediamine (HIPDM) is localized in the lung after intravenous injection, the radiopharmaceutical has been proposed as a lung imaging agent. Its potential usefulness for the detection of pulmonary emphysema was evaluated in an animal model of elastase-induced emphysema along with [99mTc]MAA lung perfusion imaging. To induce lung emphysema, Long-Evans rats (200-250 g) were given 400 IU/Kg elastase intratracheally under ether anesthesia. Four weeks after elastase treatment, 15 treated and 15 nontreated rats were paired and simultaneously imaged under a scintillation camera immediately following intravenous injection of 0.25-0.3 mCi[99mTc]MAA. The procedure was repeated 48 hr later using 0.25-0.3 mCi[123I]HIPDM. Activity in the region of interest (ROI) over the lungs was recorded after the injections. Total counts per ROI from each rat were measured and normalized by lung volume. The normalized lung activity ratio of treated/nontreated rats was computed. The mean ratios of HIPDM and MAA were 0.847 and 0.802, respectively. The significant decrease in uptake of both HIPDM (p < 0.021) and of MAA (p < 0.025) in the elastase-treated lungs indicates decrease in functioning vascular endothelium and decrease in number of pulmonary capillary vessels, respectively, reflecting damage in capillaries and small arterioles. The decrease in treated/nontreated ratios lung is consistent with a significant alteration in pulmonary function and a significant increase in mean linear intercept (p < 0.005) in treated lung. Since the imaging reflects pulmonary endothelial receptor function, [123I]HIPDM lung imaging may serve as an alternative diagnostic modality for pulmonary emphysema.

I-123 hydroxyiodobenzyl propanediamine (HIPDM) cerebral blood flow imaging demonstrating transtentorial diaschisis.

To assess the clinical significance of transtentorial diaschisis (TTD) as demonstrated by I-123 HIPDM brain imaging, SPECT and/or planar images of 35 patients with stroke, 26 patients with Alzheimer's disease (AD), 2 patients with Creutzfeldt-Jakob disease (CJD), and 1 patient with a schizoaffective disorder were analyzed. TTD was observed in 21 of the 35 patients with strokes. In 13 stroke patients, TTD was associated with large infarcts in the middle cerebral artery (MCA) territory; in the remaining 8 stroke patients, TTD was associated with internal capsule and/or basal ganglia infarcts. TTD was not associated with small occipital or parietal infarcts. Despite cortical perfusion decrements, TTD was not seen in the AD patients, the CJD patients, or the patient with schizoaffective disorder. It is concluded that 1) TTD frequently occurs following cerebral infarct of the MCA territory (60% of the patients in this sample); 2) absence of TTD in the presence of a large cerebral perfusion abnormality may represent neuronal dysfunction of the cerebral cortex; and 3) the presence of TTD without a significant cortical perfusion abnormality may indicate basal ganglia and/or internal capsule infarct.

Iodine-123-HIPDM lung imaging in pulmonary vein-banded pulmonary hypertension.

To evaluate the use of N,N,N'-trimethyl-N,-[2-hydroxy-3-methyl-5 iodobenzyl-1, 3 propanediamine iodine-123 (HIPDM) in lung imagings for the diagnosis of individual pulmonary vein stenosis, 14 single-pulmonary vein-banded rats underwent lung imaging. After i.v. injection of 250-300 microCi [123I]HIPDM lung images were recorded at 2 min by a gamma camera interfaced with a PDP computer. Banded lung demonstrated higher [123I]HIPDM radioactivity than that of nonbanded lungs. The activity ratio of banded-to-nonbanded lungs ranged from 4.0 to 1.22 (average 1.62). Technetium-99m-macroaggregated albumin (MAA) lung images showed decreased perfusion in banded lung, and normal perfusion in the nonbanded lung. Postmortem microscopic changes in pulmonary arteries and veins were compatible with the elevated pulmonary artery and venous pressure in vein-banded lung. Whether the high uptake of [123I]HIPDM in banded lungs relates to endothelial receptors for HIPDM is unknown. Nevertheless, the finding of high lung uptake in banded lung in [123I]HIPDM lung imaging may be potentially used to diagnose individual pulmonary vein stenosis.

Lung uptake on Tc-99m albumin colloid liver spleen scan and on Ga-67 scan in angiotropic lymphoma.

Lung uptake of Tc-99m sulfur colloid has been reported in various hepatic and extrahepatic diseases, and lung uptake of gallium-67 may occur in patients with various interstitial lung disease without radiographic abnormality. This may be the first case of Tc-99m albumin colloid and Ga-67 lung uptake in a patient with angiotropic lymphoma of the liver, spleen, and uterus.

I-123 HIPDM planar brain images demonstrating crossed cerebellar diaschisis.

I-123 HIPDM or IMP brain planar images, as well as SPECT images, have been useful in the detection of large lesion(s) of the cerebral cortex. Planar imaging may be useful not only for cerebral lesions, but also for a cerebellar abnormality and in certain clinical situations, such as phobia to a gantry or being too heavy for the imaging table, when SPECT imaging cannot be performed. The authors concur that a large cerebral lesion can be detected by planar images; in addition, cerebellar lesions, such as the presence of crossed cerebellar diaschisis (CCD), may be detectable by planar imaging using I-123 HIPDM. This article presents a patient with a large cerebral infarct detected by planar imaging whose CCD has been demonstrated by planar images.

Technetium-99m radiochemical assay by rapid filtration: a superior alternative to chromatography.

A new method for simultaneously measuring radiochemical purity and estimated lung trapping of colloidal technetium-99m (99mTc) radiopharmaceuticals is described. The method employs a small filtration device comprised of two stacked membrane filters, differing in membrane composition and in pore size, situated over a filtrate collection vial. Specifically, an 8-microns pore polycarbonate membrane filter is situated above a 0.22-microns pore mixed-cellulose-esters membrane filter. For assay, a diluted aliquot of radiopharmaceutical is passed through the filtration device. Technetium-99m radioactivity on the membranes and in the vial is then measured. The polycarbonate filter traps and quantitates lung-capillary-occluding particles. The mixed-cellulose-esters filter traps and quantitates radiocolloid particles irrespective of relative size. The filtrate contains free pertechnetate. Within 4 min, this method yields results that compare well with those achieved by conventional techniques. The method works equally well for large colloidal particles [( 99mTc]stannous colloid), intermediate-size particles [( 99mTc]sulfur colloid), and small-size particles [( 99mTc] antimony trisulfide colloid).

Application of I-123 HIPDM as a lung imaging agent.

N,N,N'-Trimethyl-N'-(2-Hydroxyl-3-Methyl-5-123I Iodobenzyl)-1,3-Propanediamine.Hcl (123I-HIPDM) has been used for diagnosis of patients with strokes and dementias. Since this radiopharmaceutical is also accumulated in the lung, we routinely performed a lung image or images immediately prior to cerebral planar and SPECT images after a 3-5 mCi 123I-HIPDM injection. During the past 14 months, we obtained 78 (age from 41 to 92 years, average 66.7 +/- 8.9 years; 64 males, 14 females) suspected stroke or dementia patients' lung images. All lung images were correlated to chest X-ray (CXR) or CT and other clinical data. Sixty five of 78 patients had normal lungs showing homogeneous distribution of activity throughout the lungs which correlated well to normal CXR and/or CT studies. Abnormal scintigraphic patterns of the 13 patients included lung defect (5 bronchogenic carcinoma with or without atelectasis) and decreased uptake in apices (8 chronic obstructive pulmonary disease). The findings of pulmonary intrathoracic pathologies on lung images with 123I-HIPDM suggests further evaluation of the agent for detection of localized pulmonary diseases and pulmonary physiological studies relating to amine metabolism.

Disorders of gallbladder function related to duodenogastric reflux in technetium-99m DISIDA hepatobiliary scintigraphy.

Controversy exists over the relation between gallbladder dysfunction and the propensity for duodenogastric reflux. To evaluate this, Tc-99m DISIDA hepatobiliary imaging studies in 120 patients were reviewed, excluding patients who had had cholecystectomy or subtotal gastrectomy before scintigraphy. Serial images were obtained at 5, 10, 15, 30, 45, and 60 minutes and up to 24 hours, if indicated, after intravenous injection of 5-10 mCi of Tc-99m DISIDA. Normally, the liver, bile ducts, gallbladder, common bile duct, and bowel are visualized sequentially. Reversal of the normal sequence of gallbladder (GB) and bowel visualization indicates GB dysfunction; nonvisualization of the GB reflects cystic duct obstruction or absent GB function. Duodenogastric reflux is identified by radiotracer localized in the area just below or immediately adjacent to the tip of the left hepatic lobe. The intragastric location of the tracer may be verified by oral administration of 300 uCi of Tc-99m sulfur colloid. Twenty-nine patients had duodenogastric reflux between 10 and 60 minutes after injection. Of the 29 patients, 22 had a nonvisualized gallbladder, four had reversal of appearance of GB and bowel activity, and three had a normal study. GB dysfunction or nonfunction is more frequently demonstrated when duodenogastric reflux is present than with normal gallbladder function (P less than 0.001). In conclusion, gallbladder malfunction is closely associated with duodenogastric reflux, an abnormality that may be diagnosed noninvasively by Tc-99m DISIDA hepatobiliary scintigraphy.

Iodine-123 HIPDM brain imaging findings in subacute spongiform encephalopathy (Creutzfeldt-Jakob disease).

Decreased perfusion of the left frontal and left temporoparietal cortex has been shown in [123I] HIPDM planar and single photon emission computed tomographic images of a patient with Creutzfeldt-Jakob disease (CJD) that was proven by brain biopsy and subsequent autopsy. An EEG showed diffuse, periodic discharges most prominent to the left hemisphere. Concurrent head computed tomography (CT), nuclear magnetic resonance (NMR), and cerebral angiographic studies were negative. Abnormalities demonstrated by [123I]HPDM imaging and by EEG may represent changes in neurophysiological and neurochemical status while cerebral angiography, CT, and possibly NMR register only anatomic or structural lesions. Premortem diagnosis of CJD depends on brain biopsy; the availability of the [123I] HIPDM study may provide regional cerebral neurochemical and neurophysiological information, guiding or avoiding brain biopsy in the appropriate clinical setting.

Incidentally evaluating the status of renal function in technetium-99m DISIDA hepatobiliary imaging.

During hepatobiliary imaging studies, approximately 9% of Tc-99m DISIDA normally is excreted via the kidney. In routine 2, 5, 10, 15, 30, 45, and 60-minute images, the kidneys and urinary bladder are best visualized at 5-10 minutes and after 10-15 minutes, respectively. Nonvisualization of the kidney and/or urinary bladder may indicate renal dysfunction. To evaluate this hypothesis, Tc-99m DISIDA hepatobiliary images of 63 patients were correlated with concurrent serum BUN and creatinine levels (measured within 24 hours of the hepatobiliary study). Serum creatinine and BUN values were normal in patients with renal visualization. In patients without renal visualization, 17 of 19 had abnormal BUN and creatinine levels. The values of BUN and creatinine were significantly elevated (P less than 0.001) in patients without renal visualization when compared with those showing renal visualization. One patient had visualization of a single kidney due to a nephrectomy; in another, persistent visualization was due to hydronephrosis. Nonvisualization of the kidneys and/or urinary bladder suggests abnormal renal function, and asymmetric renal activity raises the possibility of renal disease.

Demonstration of pulmonary mass defect by iodine-123 N,N,N'trimethyl-N'[2-hydroxy-3-methyl-5-iodobenzyl]-1,3-propanediamine lung imaging.

A patient whose huge lung mass was demonstrated as a large defect on I-123 N,N,N'trimethyl-N'[2-hydroxy-3-methyl-5-iodobenzyl]-1,3-propanediamine (HIPDM) lung imaging is presented. I-123 HIPDM, a lipophilic agent, is designed for early detection of abnormal cerebral perfusion. Since up to 50% of the administered agent is accumulated and perhaps metabolized in the lung, the radiopharmaceutical may be potentially useful for detection of pathology of the lung in addition to evaluation of pulmonary amine metabolism.

Diffuse thoracoabdominal radioactivity seen in bone imaging.

Diffusely increased radioactivity in the thoracoabdominal region (lower thorax and/or upper abdomen) occasionally has been observed when performing Tc-99m phosphonate bone studies. To assess the significance of activity in this finding, 1100 bone scintigrams were reviewed and the clinical data and other diagnostic imaging procedures were evaluated in these cases. With the exclusion of Tc-99m sulfur colloid liver-spleen scans 18 patients were found to have mild but diffuse increased radioactivity in the thoracoabdominal region either on the right or left. Clinical findings in these cases with abnormal uptakes were pleural effusions (six cases), hepatic colonic metastases (six cases), splenic metastases from bronchogenic carcinoma (one case), abdominal and peritoneal colonic metastases (one case), a massive metastatic squamous cell carcinoma (from lung) in the right lower chest (one case), and defective radiopharmaceuticals (three cases). Since the defective radiopharmaceuticals contained 5% of hydrolyzed reduced Tc-99m colloid by thin-layer chromatography, each of three patients received approximately 740 mu Ci of Tc-99m sulfur colloid. Factors to be considered in the interpretation of diffuse thoraco-abdominal activity from a bone agent should include splenic or hepatic metastases, a Tc-99m sulfur colloid splenic or hepatic metastases, a Tc-99m sulfur colloid study within the previous 24 hours, pleural effusion, faulty radiopharmaceuticals, and abdominal and peritoneal colonic metastases.

Localization of 99mTc-HMDP in hepatic metastases from colonic carcinoma.

To evaluate the significance and frequency of skeletal imaging agent localization in hepatic metastases from colonic carcinoma, scintigrams from 54 patients were retrospectively studied. Of 54 patients, 22 had hepatic metastases, and skeletal metastases were present in seven of 54. Six of the seven patients with skeletal metastases had concurrent hepatic deposits. Two patterns of bone agent localization in liver metastases occurred: diffuse and mild (10 patients) and ringlike in appearance (two patients). Twelve of the 22 patients had localization of skeletal imaging agent in hepatic metastases and extensive or large liver lesions. Concurrent serum calcium values for nine of 12 patients were reviewed; none had a high level of serum calcium. Among available plain films and /or CT scans of the abdomen for 21 of the 22 patients, only one patient with extensive colonic metastases had multiple calcifications shown on CT but not seen in plain films. The data indicate a high frequency of hepatic metastases in colon carcinoma (22/54, 40%) and a high frequency of skeletal imaging agent localization in the hepatic colonic metastases (12/22, 54.5%). Once skeletal metastases are observed, there are almost always hepatic metastases present (6/7). There was no relation between elevated serum calcium values and bone agent localization in hepatic deposits. The relation between skeletal imaging agent localization or radiographic calcifications and histopathology of colonic carcinoma was inconclusive. The presence of bone agent localization in a 99mTc hydroxymethylene diphosphonate (HMDP) bone study indicates colonic hepatic metastases that are substantially widespread and/or bulky.