Clinical Nuclear Medicine最新文献

Abstract: Cholecystokinin 2 receptor (CCK 2 R) is a promising target for imaging and treatment of medullary thyroid cancer due to its overexpression in over 90% of tumor cells. 68 Ga-DOTA-CCK-66 is a recently introduced PET tracer selective for CCK 2 R, which has shown favorable pharmacokinetics in vivo in preclinical experiments. In order to further investigate safety and suitability of this tracer in the human setting, whole-body distribution and radiation dosimetry were evaluated.

Patients and methods: Six patients with a history of medullary thyroid cancer were injected intravenously with 169 ± 19 MBq of 68 Ga-DOTA-CCK-66. Whole-body PET/CT scans were acquired at 10 minutes, 1 hour, 2 hours, and 4 hours after tracer injection. Time-activity curves per organ were determined, and mean organ-absorbed doses and effective doses were calculated using OLINDA/EXM.

Results: Injection of a standard activity of 150 MBq of 68 Ga-DOTA-CCK-66 results in an effective dose of 4.5 ± 0.9 mSv. The highest absorbed organ doses were observed in the urinary bladder wall (40 mGy) and the stomach (15 mGy), followed by the kidneys (6 mGy), as well as the liver and the spleen (3 mGy each). CCK 2 R-expressing tumor manifestations could be detected in 2 of the 6 patients, including lymph node, bone, and liver metastases.

Conclusions: 68 Ga-DOTA-CCK-66 exhibits a favorable dosimetry. Beyond physiologic receptor expression of the stomach, no other relevant tracer accumulation could be observed, rendering this organ at risk in case of subsequent radioligand therapy using 177 Lu-DOTA-CCK-66.

Abstract: A 64-year-old woman with meningioma presented with left-sided lenticulostriatal ischemia following craniotomy and debulking of a sphenoid wing meningioma. For subsequent radiotherapy planning, an SSTR-targeted PET/CT using the novel ligand 18 F-SiTATE was performed 2.5 months thereafter. The meningioma remnants showed transosseous, intrasellar, and perivascular extension around the internal carotid artery with strong SSTR expression. Moreover, there was focal 18 F-SiTATE uptake in the left caudate and corresponding contrast enhancement due to postischemic blood-brain barrier disruption and reactive SSTR expression. Therefore, increased cortical or subcortical SSTR PET signal may be related to ischemic changes even in the subacute stage after initial stroke.

Abstract: "Burned-out" testicular tumor is a very rare clinical phenomenon, which refers to the presence of a metastatic germ cell tumor with no clinical findings in the testicle due to spontaneous regression of the primary testicular lesion. We present an unusual case of burned-out testicular embryonal germ cell carcinoma presenting as an extensive inferior vena cava tumor thrombus with malignant pulmonary embolism in which FDG PET/CT played a pivotal role in detecting the extent and significance of the disease.

Abstract: A 54-year-old woman with a history of end-stage renal disease was found to have infiltrative cardiomyopathy by echocardiography. 99m Tc-pyrophosphate ( 99m Tc-PYP) scintigraphy was positive with a remarkable myocardial uptake. Gene test found a mutation of AGXT , confirming a final diagnosis of primary hyperoxaluria. Radiotracer uptake was due to high myocardial oxalate deposition. This case illustrates false positivity of the 99m Tc-PYP scan caused by hyperoxaluria-associated cardiomyopathy, which raises awareness for other conditions apart from amyloid cardiomyopathy.

Purpose: Hypophysitis occurs in up to 10% of patients treated with immune-checkpoint inhibitors (ICIs). MRI shows no abnormalities of the pituitary gland in one third of patients. A delayed diagnosis increases the risk for life-threatening adrenal crisis, underscoring the need for early detection. This study evaluates the diagnostic accuracy FDG PET/CT in detecting ICI-induced hypophysitis in a cohort of melanoma patients.

Materials and methods: Patients with metastatic melanoma and ICI-induced hypophysitis, who underwent FDG PET/CT 90 days before to 10 days after diagnosis, were compared with an age- and sex-matched control group of patients undergoing ICI treatment without signs of hypophysitis. The ratio of SUV max of the pituitary gland to the SUV mean of the blood pool (target-to-background ratio [TBR]) was calculated. Diagnostic accuracy of the TBR was assessed using area under the receiver operating characteristics curve analysis.

Results: A total of 28 patients was included. The majority of patients with hypophysitis received ipilimumab/nivolumab (64.3%, 9/14). Visual assessment of the TBR distribution demonstrated a positive correlation with decreasing time to diagnosis. To evaluate diagnostic performance, only patients with FDG PET/CT 50 days before to 8 days after diagnosis (11/14) were included. TBR was significantly higher in these compared with the control group (median [interquartile range], 2.78 [2.41] vs 1.59 [0.70], respectively; P = 0.034). A sensitivity of 72.7% and a specificity of 90.9% were achieved at a TBR threshold of 2.41 (area under the receiver operating characteristics curve = 0.769).

Conclusions: Our findings suggest that, in patients undergoing ICI treatment for metastatic melanoma, a pituitary TBR of approximately 2.4 may indicate impending ICI-induced hypophysitis.

Abstract: We present MDP bone scan findings of radiation pneumonitis in a 45-year-old woman with invasive ductal carcinoma of the right breast, classified as stage IIIa, T3N2M0. The patient underwent a modified radical mastectomy, neoadjuvant chemotherapy, and subsequent radiotherapy, receiving the last session 7 months before the bone scan. Whole-body images acquired 3 hours postinjection of 20 mCi (730 MBq) 99m Tc-MDP showed incidentally increased uptake in the right hemithorax, confined to the lung parenchyma of the right lung on SPECT/CT images.

Purpose: This study aimed to evaluate the ability of 18 F-FDG PET/CT metabolic parameters to predict the histological response to neoadjuvant chemotherapy in patients with osteosarcoma and Ewing sarcoma.

Patients and methods: This systematic review and network meta-analysis adhered to the PRISMA-NMA and Cochrane guidelines. Electronic databases were searched from January 2008 to January 2024; this search was supplemented by snowballing methods. The risk of bias was evaluated with QUADAS-2, and evidence certainty was assessed using the GRADE approach. The prognostic value of 18 F-FDG PET/CT parameters, including pretreatment and posttreatment SUVs (SUV1, SUV2 and the SUV2/SUV1 ratio), metabolic tumor volume (MTV1, MTV2, ΔMTV), and total lesion glycolysis (TLG1, TLG2, ΔTLG), was examined.

Results: The meta-analysis of 18 studies (714 patients) identified the ΔTLG, ΔMTV, and SUV ratio as superior predictors of histological response. The changes in metabolic activity, as indicated by these parameters, provided a robust indication of treatment effectiveness. Baseline parameters showed limited predictive value compared with posttreatment assessments. The study's robustness was confirmed through meta-regression, which revealed that the predictive value of the SUV2 and SUV ratio was consistent across various cutoff thresholds.

Conclusions: 18 F-FDG PET/CT metabolic parameters, particularly those measuring changes posttherapy, are effective in predicting the histological response in patients with osteosarcoma and Ewing sarcoma. These findings underscore the potential of 18 F-FDG PET/CT in guiding early treatment decisions, thereby enhancing personalized therapeutic approaches.

Abstract: Invasive lobular breast cancer (ILBC) is characterized with low tracer uptake on 18 F-FDG PET images. ILBC metastasis to gastrointestinal tract is a rare clinic scenario. We present a case of ILBC who presented with gastric metastasis and diagnosed with 68 Ga-FAPI-46 PET/CT and 18 F-FDG PET/CT images.

Abstract: A 34-year-old woman underwent 18 F-FDG PET/CT scan following a diagnosis of an invasive mole. Although CT indicated multiple lung metastases, FDG uptakes were not evident. In contrast, FDG uptakes were observed in the pelvic lesion including the left ovary, suggestive of ovarian metastasis. MRI disclosed a ring-shaped enhancement typical of a corpus luteum. This corpus luteum was supposed to be maintained by the elevated human chorionic gonadotropin excreted from the invasive mole. This case underlines the importance of careful interpretation of 18 F-FDG PET/CT in the evaluation of invasive moles, highlighting potential false positive in corpus luteum.