Wei-Jen Shih

F-18 FDG PET demonstrates crossed cerebellar diaschisis 20 years after stroke.

Stroke produces an area of focal damage and distant areas of reduced blood blow and metabolism termed diaschisis. Tc-99m ECD and HMPAO brain SPECT have demonstrated crossed cerebellar diaschisis (CCD) in patients with cerebral cortical infarct. SPECT findings reflect abnormal cerebral blood flow. CCD as shown on F-18 FDG PET reflects abnormal reflects glucose metabolism. We present the case of a patient with laryngeal cancer who also had a stroke in the left cerebral hemisphere involving the territory of the middle cerebral artery 20 years ago. This patient underwent PET, including the head and neck. A current brain F-18 FDG PET exhibited hypometabolism in the contralateral cerebellum (CCD) as well as hypometabolism of the primary insult in the left cerebral hemisphere. These findings reflect partial impairment or diminished glucose metabolism in the primary insult to the cerebrum and contralateral cerebellum. In addition, this patient illustrates that on PET imaging, CCD could be demonstrated 20 years after a stroke.

False-positive results for hepatic hemangioma on Tc-99m RBC SPECT caused by a liver metastasis from small-cell lung carcinoma.

Tc-99m RBC liver imaging has been used to confirm hemangiomas on inconclusive US and CT studies. A hot spot on the Tc-99m RBC blood pool imaging is characteristic of a hemangioma. A patient with a suspected hemangioma on US whose Tc-99m RBC showed a hot area was found to be a metastatic lesion from a small-cell carcinoma of the right lung.

Duodenogastric reflux shown on raw data images on dual-isotope gated cardiac Tc-99m tetrofosmin SPECT in a patient with esophagectomy for Barrett esophagus

Extracardiac activity in the thorax can be malignant or benign on dual-isotope raw data images. The authors present a postesophagectomy patient for Barrett esophagus that resulted in duodenogastroesophageal reflux exhibited on raw data images of dual-isotope cardiac SPECT with Tl-201 and Tc-99m tetrofosmin. The incidental extracardiac activity in the thorax should be included in comprehensive cardiac SPECT interpretation.

Prediction of radionuclide bone imaging findings by Gleason histologic grading of prostate carcinoma.

To evaluate a relationship between Gleason scores and Tc-99m HMDP bone imaging findings, data from 48 men (aged 45 to 77; mean, 67) with prostate carcinoma who had a bone imaging study at the time of presentation were reviewed. Cumulative Gleason scores were divided into two groups: high scores (6–10), 32 men; low scores (2–5), 16 men. Of the 32 men with high Gleason scores, 15 tested positive for multiple metastases and 17 tested negative. Tumors of the 16 men with low Gleason scores were negative for metastasis. A chi-square association between Gleason scores and the presence of metastases, either of a superscan pattern or multiple metastases, was 10.9 (1 df, P < 0.001). The results indicate that a super-scan pattern or multiple metastases were found exclusively in the bone images of patients with high histologie grades; bone images negative for metastases were associated with low-grade tumors. We conclude that positive bone imaging for metastases at the initial scan occurs only in patients who have high Gleason scores, that patients with high Gleason scores might or might not have skeletal metastasis, and that skeletal metastasis is not predictable in patients with low Gleason scores.

Intrathoracic gastric activity on cholescintigraphy results in a large hiatus hernia with duodenogastric reflux.

Abstract: When a radiopharmaceutial is seen in the intrathoracic cavity on Tc-99m iminodiacetic acid (IDA) cholescintigraphy, basically 2 abnormalities are seen: first the stomach, such as a hiatus hernia, which is abnormally located in the thoracic cavity, and duodenogastric reflux (bile) which is simultaneously seen. However, intrathoracic gastric activity seen on Tc-99m IDA hepatobiliary scintigraphy is rarely documented in a patient with hiatus hernia. This report is of an 83-year-old man with a large hiatus hernia with duodenogastric reflux who underwent hepatobiliary scintigraphy; the scans show an area of increased activity on the top of the liver due to duodenogastric reflux in a large hiatus hernia. This was confirmed by surgery: the patient successfully underwent laparoscopic paraesophageal hernia repair with Nessen fundoplication and laparoscopic cholecystectomy.

Hashimoto thyroiditis and Takayasu aortitis: visualization of the thyroid gland and ring appearance of the mediastinum on F-18-FDG PET.

A woman with Hashimoto thyroiditis, treated with levothyroxine for 4 years, complained of chest pain that radiated to the neck and had progressively worsened for 2 months. CT of the chest showed circumferential thickening of the ascending aorta and aortic arch, compatible with Takayasu arteritis. She underwent F-18 FDG PET imaging, which revealed an abnormal thyroid gland and a ring-like appearance of the mediastinum.

Comparative Ga-67 citrate and bone scintigraphy in disseminated blastomycosis.

&NA; Blastomycosis is a systemic illness, and the disease eventually spreads to multiple organs or develops multifocal involvement. Cutaneous and skeletal involvement are the two most common extrapulmonary manifestations. Because serologic and skin tests are not reliable, diagnosis of the disease is made only by visualization of the organism in tissue, sputum, exudates, or by culture. Ga‐67 citrate and whole‐body bone imaging may play important roles in diagnosis. The authors describe a patient with disseminated blastomycosis proved by skin biopsy who underwent bone and Ga‐67 citrate wholebody imaging. Both bone and Ga‐67 citrate studies showed a large area of increased uptake in the entire upper third of the proximal right tibia, and focal lesions in the left femur and in the skin of the chin. Ga‐67 citrate imaging did not reveal the T‐10 vertebra and two rib lesions, a pulmonary lesion, or other skin lesions. The patient received amphotericin B and traconazole therapy. The right tibia lesion resolved, as evidenced by a radiologic examination performed 5 months later. References

Enlarged photon-deficient area in expected site of renal allograft on Tc-99m DTPA study. A sign of renal vein thrombosis.

Tc-99m DTPA renal imaging has been routinely used in postrenal transplant evaluation. A patients Tc-99m DTPA studies after transplantation are presented, showing a large photon-deficient area in the region of the allograft on the third postoperative day. The photondeficient area is two to three times larger than that seen in the original, functioning allograft on the first postoperative day. Enlarged to a weight of 530 g, the allograft on gross and microscopic examination confirmed renal vein thrombosis. Enlargement of the photon-deficient area at the anatomic site of the allograft indicates a scintigraphic pattern of renal vein occlusion incompatible with a viable allograft.

Active bleeding in hematoma of the abdominal rectus muscle shown by Tc-99m red blood cell scintigraphy: compared with CT.

A patient with cirrhosis of the liver complicated with left rectus muscle hematoma following paracentesis underwent consecutive noncontrast CT images and a novel Tc-99m red blood cell (RBC) bleeding scan. Six liters of clear yellow fluid were withdrawn. Progressive enlargement of a left rectus muscle hematoma was diagnosed by 3 consecutive CT scans and confirmed by a Tc-99m RBC bleeding scan. Although consecutive CT scans showed progressive enlargement of the hematoma, the radionuclide study showed an active bleeding site.

Fluorine-18-FDG-PET Demonstrating Malignant Pleural Effusion from Esophageal Carcinoma

Malignant pleural effusion is the most common complicated by primary pulmonary carcinoma, but is seldom in patients with esophageal carcinoma. We present a patient with a 5-6 month history of gradual dysphagia of solid foods and gurgling with liquids whose computed tomography (CT) images of the chest showed left pleural effusion. 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging revealed increased FDG uptake in the distal end of esophagus and in the posterior left chest wall. An aspiration of the left-side pleural effusion was done; cytologic examination of the aspirated effusion was positive for malignancy, consistent with adenocarcinoma of esophagus. The clinical roles of PET imaging in patients with malignant pleural effusion are discussed.