Parathyroid adenoma radiation dose simulator

INTRODUCTION

As the number of radioisotope localization cases increased at our facility, the pathologists expressed concern regarding radiation exposure from parathyroid specimens. The radiation safety officer was consulted to analyze personnel radiation protection issues.

METHODS

Analysis of simulated specimens was performed for a range of activities and masses corresponding to the values that have been observed. The radiation dose rates from these samples were measured using a Ludlum Model 14C survey meter with a Model 44-38 energy compensated GM probe and a Ludlum Model 3 Geiger counter with a Model 44-9 "pancake" style GM probe (Ludlum Measurements, Inc., Sweetwater, Texas). Additionally, 3 consecutive 10-second counts were performed using a USSC Navigator Gamma Guidance System (United States Surgical Corporation, Norwalk, CT). The per-second average readings were recorded.

RESULTS

Our sample count-rates ranged from 139 to 2,830 counts/second. The majority of these values fell within the 100 to 1,000 count/second range typically observed during surgery. Based on our sample set, our dose rates at contact with these samples ranged from 0.17 to 4.0 mR/hour depending on the instrument, sample activity, and sample volume. The variation between count rate and dose rate for each observed volume varied linearly with activity.

CONCLUSION

Based on these observed radiation doses, we concluded that there is no need to hold parathyroid specimens for 24 to 48 hours after surgical removal for handling because the typical radiation doses are quite low and would not result in significant radiation exposure to pathology personnel.

Accidental small-bowel puncture, and importance of patient positioning, during isotopic peritoneography: a case report

A 47-y-old woman with chronic liver disease, who had previously undergone placement of a peritoneal venous shunt without ascites, presented with a chronic right pleural effusion. The first attempt at radionuclide injection resulted in an accidental small-bowel injection with consequent intraalimentarily induced nuclear small-bowel followthrough. I have not read of this interesting complication in the literature. She did not have a bowel obstruction. A repeated study 2 d later demonstrated an obstructed peritoneal shunt and right hemidiaphragmatic pleural leak best seen with the patient upright.

Positron emission tomography and Paget disease: hot is not necessarily malignant

The authors imaged a lung cancer patient with an enlarging solitary pulmonary nodule and incidentally found intense activity in the right proximal humerus consistent with known Paget disease confirmed via plain film and computed tomography (CT) without change in the CT appearance or symptoms during the next 7 months. The alkaline phosphatase and alanine amino transferase (ALT) levels were in the normal ranges. Their findings of high uptake with normal alkaline phosphatase and ALT are contradictory to previous reports. The authors present a case of Paget disease that appeared "hot" on positron emission tomography initially thought to be a malignant transformation that typically demonstrated high uptake.

Fractured osteophyte demonstrated on SPECT and computed tomography

ABSTRACT We present an interesting case of a fractured osteophyte causing back pain that was demonstrated both on bone single photon emission computed tomography (SPECT) and computed tomography (CT). The magnetic resonance images, thoracic anterior spine plain radiograph, whole-body bone scan passes, and thoracic spot view were not impressive. Bone SPECT was the impetus for getting the CT scan. The CT scan not only demonstrated the osteophyte but a pseudarthrosis that was probably causing the pain. If it were not for the positive SPECT bone scan, the CT scan would not have been ordered after unimpressive magnetic resonance imaging.

Unsuspected widespread cardiac sarcoma in a child

The case of a patient with an undifferentiated metastatic cardiac sarcoma is presented. A thallium-201 tumor study was performed to evaluate lung nodules. Thallium-201 chloride was injected intravenously and whole body images, as well as single photon emission computer tomography (SPECT) imaging of the chest, were obtained and reconstructed. They were displayed in three planes and then reconstructed again in cardiac planes. Multiple unsuspected metastases were found in the lower extremities. Viable tumor was demonstrated in both cerebral hemispheres. The lung nodules were not clearly identified. However, cold areas in the myocardium were detected corresponding to the findings on magnetic resonance imaging (MRI). In retrospect, at least one abdominal metastasis was identified. Whole body tumor imaging plays an important role in finding unsuspected primaries and in staging neoplasms to optimize patient care.

Incidental massive pericardial effusion diagnosed by myocardial perfusion imaging

A report on an unusual case of pericardial effusion and tamponade that was found incidentally on myocardial perfusion imaging. This was later confirmed by echocardiography and subsequently treated with pericardiocentesis. Two-dimensional echocardiography is still the "gold standard" for diagnosing pericardial effusion. Nuclear cardiac imaging will probably never have a primary role in the diagnosis of pericardial effusion. However, it may be helpful when the diagnosis of pericardial effusion has not been considered and when this condition is suggested by nuclear imaging findings. The echocardiogram underestimated the amount of pericardial effusion compared to myocardial perfusion imaging in this case, and in contrast to previous published reports. Further, prospective studies need to focus on the sensitivity and specificity of sestamibi nuclear scans in the qualitative and quantitative assessment of pericardial effusions.

The day of contamination

OBJECTIVE

We present 3 cases of suspected radioisotope urinary contamination that occurred on a single day. Because net clearance is via the kidneys, the injected dose is excreted in patients' urine. It is important to recognize the patterns of urinary contamination to avoid reporting false-positive abnormalities.

MATERIALS AND METHODS

(99m)Tc-Medronate was administered intravenously and whole-body bone scans and spot views were obtained 2-3 h later.

RESULTS

Two cases of urinary contamination were confirmed, and the third case was false-positive with a urinary collection leg bag seen in an orthogonal view.

CONCLUSION

We believe that urinary contamination is probably the most common type of contamination. There are distinct urinary contamination patterns among male and female patients. It is unusual to find so many cases of contamination on a single day in our institution. Few statistics are widely available on the number or percentages of contamination for specific radiopharmaceuticals.

Recombinant TSH-stimulated, radioguided differentiated thyroid carcinoma surgery

A novel approach to locating and surgically resecting occult metastatic foci in a 25-year-old female with a history of total thyroidectomy for differentiated thyroid carcinoma was attempted. Two iodine-131 (131I) body scans were performed: one after the patient underwent a 2-3 week thyroxine withdrawal, and another the following week utilizing recombinant TSH-stimulation. Then the patient was treated with 151 mCi of 131I, and 2 weeks later, without further hormonal manipulation, she had radioguided surgery. The two diagnostic 131I body scans were negative, but the post-therapy scan was positive. Two weeks later after pre-operative skin marking, radioguided surgery localized metastatic foci in the central compartment neck just dorsal to the suprasternal notch. No other foci were identified with the probe at surgery. At pathology, 2 of the 12 nodes were positive, as well as a 1 mm metastatic focus in the fat. Provocative imaging protocols, aggressive radioiodine therapy, and the novel use of radioguided surgery to attempt a cure in an 131I image-negative metastatic thyroid carcinoma patient was performed. No other cases using these combined diagnostic and therapeutic efforts have been reported in the literature.

Thyroid carcinoma: iodine-131-negative whole-body scan reverses to positive after a combination of thyrogen stimulation and withdrawal

PURPOSE

Reports state that scan results for as many as 25% of patients with differentiated thyroid carcinoma will convert to iodine-131 (I-131) negative over time with positive thyroglobulin levels. Tl-201, positron emission tomography (PET), and sestamibi or tetrofosmin have all helped to identify I-131-negative thyroid carcinomas. The authors have identified a case of reversal of I-131 findings from negative to positive after short-term thyroxine withdrawal combined with treatment with recombinant human thyroid-stimulating hormone (rhTSH).

MATERIALS AND METHODS

The authors obtained multiple I-131 whole-body scans with 4-week thyroid hormone withdrawal, post-I-131 therapy scans, nonthyroid withdrawal Tl-201 chloride whole-body tumor images, and finally combined 2.5-week thyroid hormone withdrawal and rhTSH-stimulation I-131 whole-body scans before and after therapy.

RESULTS

The authors examined one patient during a period of 9 years whose I-131 whole-body scan results were at first positive and then became negative. After a combination of rhTSH stimulation and thyroid hormone withdrawal, the results changed again to I-131 positive.

CONCLUSIONS

This is the first known case in which I-131 findings changed from negative to positive. A combination of rhTSH stimulation and nearly adequate withdrawal may help convert more I-131-negative whole-body scans to positive.

Penile implant on bone scan imaging: a case study

We present an unusual case of the incidental finding of a penile implant on a whole-body bone scan obtained for back pain in a patient with osteoporosis and vertebral body fractures. On 2 separate occasions, this patient underwent 3-h delayed whole-body bone scanning with (99m)Tc-methylene diphosphonate. The images showed acute and then subacute vertebral body fractures. On both imaging occasions, the bone scan that included the region of the implant clearly showed the penis, but visualization was better on the second scan. Penile implants have not been described in the nuclear medicine literature, and it is important to recognize the diagnostic possibilities when penile photopenia is identified.

Diagnosing and treating small-cell carcinomas of prostatic origin

PURPOSE

Small-cell carcinoma is very aggressive, metastasizes early and often, and does not respond to most chemotherapy regimens. In approximately 50% of cases of prostate cancer, tumors are a combination of small-cell carcinoma and androgen-sensitive adenocarcinoma. It is widely believed that no successful treatment exists for androgen-independent prostate cancer.

METHODS

A 67-year-old man had undergone androgen ablation therapy and radical prostatectomy for prostate cancer followed by bilateral orchiectomy, limited radiation therapy, and unsuccessful chemotherapy for pain-causing metastatic bone disease. Biopsy and immunohistochemical analysis revealed neuroendocrine differentiation of the cancer. The full extent of metastatic disease was assessed successfully using In-111, a somatostatin derivative. Octreotide acetate was used to treat the tumors.

RESULTS

In-111 OctreoScan scintigraphy was more sensitive in the diagnostic demonstration of metastatic foci than was bone scanning. Therapy with the cold somatostatin derivative resulted in a rapid and significant relief of pain with significant tumor shrinkage. The patient remained in remission for at least 10 weeks, when he was lost to follow-up.

CONCLUSIONS

Somatostatin analogs and their radionuclide and cytotoxic derivatives are recommended as adjuvant treatments for prostate carcinoma, especially in those patients who are at high risk for carcinoma recurrence after radical prostatectomy and who have advanced prostate carcinoma at the time of relapse. Because small-cell carcinomas of the prostate and lung are identical, these analogs may be useful in the detection and treatment of these tumors as well.

Rapid detection of acute appendicitis with Tc-99m-labeled intact polyvalent human immune globulin

BACKGROUND

Acute appendicitis remains problematic for emergency clinicians. A rapid and definitive test is needed for detecting acute appendicitis before surgical intervention. The purpose of this clinical trial was to determine the efficacy of Tc-99m-labeled intact polyvalent human immune globulin (Tc-99m IgG) in the evaluation of acute appendicitis.

STUDY DESIGN

Thirty-five patients with clinically suspected acute appendicitis were evaluated with Tc-99m IgG. After the intravenous injection of 25 mCi (92.5 MBq) of Tc-99m IgG, anterior flow, single photon emission computerized tomography (SPECT) and planar delayed images of the abdomen were obtained. Any abnormal focal uptake of Tc-99m IgG in the right lower quadrant was considered to be a positive scan.

RESULTS

Twenty-one patients with a positive Tc-99m IgG scan underwent laparotomy and were found to have acute appendicitis. Of the 14 patients who had negative scans, 7 underwent surgery. In this series, Tc-99m IgG study yielded 21 true-positive, 12 true-negative, and 2 false-negative results with a sensitivity, specificity, and accuracy of 91%, 100%, and 94%, respectively. The positive and negative predictive values were 100% and 86%, respectively. There were no false-positive results.

CONCLUSIONS

Tc-99m IgG scintigraphy can provide the clinicians a simple, rapid, and definitive test for the diagnosis of acute appendicitis.

Gorham's disease of the radius: radiographic, scintigraphic, and MRI findings with pathologic correlation. A case report and review of the literature

A rare case of Gorham's disease affecting the radius in a 46-year-old woman is presented. It was studied by plain radiography, MRI, and scintigraphy, including three-phase radionuclide bone scan and thallium scan. Three-phase bone scan demonstrated slightly decreased activity in the affected portion of the forearm in the early phase, but showed increased activity on the blood pool and delayed imaging. A thallium scan revealed no abnormalities. Histopathologic examination revealed osteoclastic activity and scar tissue with minimal remaining vasculature.

Hemobilia presenting as intermittent gastrointestinal hemorrhage with sincalide confirmation. A case report

An 82-year-old man had his third episode of melanotic stool. Two previous workups had failed to localize the source of bleeding. A Tc-99m labeled RBC scan visualized the gallbladder early in the study. Administration of sincalide visually decreased the activity, confirming gallbladder activity. Three months later, at his second surgery, hepatic metastases were finally identified as the source of bleeding. In retrospect, the hepatic activity is inhomogeneous with at least two cold defects that could have represented hepatic metastases.

Direct comparison of Tc-99m DTPA and Tc-99m HMPAO for evaluating brain death

Portable cerebral perfusion studies provide a quick and accurate alternative to traditional confirmatory examinations (such as four-vessel angiography and electroencephalography) to determine brain death. The authors retrospectively analyzed 26 cerebral perfusion studies using both Tc-99m DTPA and Tc-99m HMPAO. The flow agents gave identical results. Additionally, the delayed-phase Tc-99m HMPAO images gave the same results for brain death (14 positive and 12 negative) as the flow images from either agent. Because the Tc-99m HMPAO delayed images can be used for diagnosis, many technical problems become less crucial. Unlike Tc-99m DTPA, Tc-99m HMPAO normally visualizes the gray matter of the cerebellum, midbrain, and medulla. These areas must be evaluated to ensure that they meet the strict criteria for brain death. These differences and the present study suggest that Tc-99m HMPAO is a superior agent for cerebral perfusion studies to determine brain death.

Air traffic controller lightning strike

Andersen Air Force Base in Guam boasts the tallest control tower in the Air Force. In 1986, an air traffic controller was struck by lightning as the bolt proceeded through the tower. Although he received only a backache, the lightning left a hole with surrounding scorch marks on his fatigue shirt and his undershirt. The lightning strike also ignited a portion of the field lighting panel, which caused the runway lights to go out immediately. Lack of a lightning rod is the most likely reason the controller was struck. Proper precautions against lightning strikes can prevent such occupational safety hazards.

Radionuclide imaging in forme fruste of melorheostosis

Scintigraphy was instrumental in two histologically proven cases of forme fruste melorheostosis. Radionuclide bone scans demonstrated a moderately increased uptake of radiopharmaceutical localized to the "flowing" cortical hyperostosis of melorheostosis observed radiographically. The medullary portion of the affected bones showed no increase in tracer activity. In one case, imaging with Tl-201 chloride demonstrated increased focal activity of the lesion. These scintigraphic findings can help distinguish the mildest manifestation (forme fruste) of melorheostosis from the well-ossified lesions of myositis ossificans and parosteal or periosteal osteosarcoma. The findings of MRI are also described in one patient.

False-positive Meckel's imaging and true-positive imaging of a gastrointestinal bleed and surgical lesion

A 76-year-old woman presented after 1 day of melena and anemia. A Meckel's scan revealed an upper mid abdominal focus of activity that paralleled stomach activity. Later, the surgeon removed the corresponding lesion in the mid ilium. Pathology confirmed that the lesion was a carcinoid tumor, not ectopic gastric mucosa. The false-positive Meckel's scan had revealed the true source of gastrointestinal bleeding and an unsuspected solitary carcinoid tumor. This is the third published case of a carcinoid tumor discovered by a false-positive Meckel's scan.

Late "rim sign"--a variant of an old sign

Classically, the "rim sign" has been described throughout the hepatobiliary scan. The authors present a case of a late rim sign visualized at 25 minutes postinjection that proved to be acute upon chronic acalculous cholecystitis without gangrene.

Osteosarcoma presenting as intestinal obstruction

Osteosarcoma commonly presents with osseous and pulmonary metastases. We present an unusual case of extraosseous metastatic abdominal chondroblastic osteosarcoma presenting as intestinal obstruction.

The determination of dual pancreatic and renal transplant graft vascular patency with Tc-99m HMPAO

Combined pancreatic-renal transplants promise the restoration of physiologic control of serum glucose and normal renal function. As pancreatic transplantation becomes more common, there is an increased need for rapid, noninvasive evaluation of vascular graft patency and function. Pancreatic transplants share the renal transplant's complications of ischemia at harvest but are at greater risk. Tc-99m HMPAO is a lipophilic complex that clears rapidly from the blood after intravenous injection, and tissue accumulation is proportional to regional perfusion. Using Tc-99m HMPAO to monitor the vascular competency has the advantage of a high count rate during dynamic scintigrams but, in contrast to Tc-99m DTPA, has excellent delayed static images. Four patients who received combined cadaveric pancreatic-renal transplants and had a total of eight Tc-99m HMPAO scintigraphic examinations were reviewed.

Unsuspected meningitis diagnosed by In-111 labeled leukocytes. A case report

Clinically unsuspected bacterial meningitis was found in a patient with fever of unknown origin. Blood and urine cultures were negative for growth. Chest radiography and abdominal CT were negative for infection. Triple-phase bone imaging was performed to rule out osteomyelitis from a gunshot wound. A left posterior iliac crest hot spot may have represented osteomyelitis, but In-111 labeled leukocyte imaging instead disclosed unsuspected meningitis. The CSF culture after the imaging was positive for Enterobacter aerogenes.