A rare case of rectal carcinoma and prostate carcinoma with coexistent Paget’s disease mimicking bone metastases in both 18F-FDG and 68Ga PSMA PET/CT

Paget disease of bone in an elderly patient with chronic renal disease and weight loss: A case report

RATIONALE

Asymptomatic Paget disease of bone (PDB) is mostly diagnosed by accidental finding of osteolytic lesion on the plain film. However, in elderly patient with chronic renal insufficiency and weight loss, it is crucial to differentiate PDB from metabolic and metastatic bone diseases for further treatment and better outcome.

PATIENT CONCERNS

An 80-year-old man with chronic kidney disease presented to our emergency department due to fever with chillness for a day, while the abdominal fullness, anorexia, and weight loss had been noted for 3 months. Mixed osteoblastic and lytic changes in the pelvic bone were accidentally found on the abdominal plain film.

DIAGNOSIS

The patient was diagnosed as asymptomatic PDB and urinary tract infection of Pseudomonas aeruginosa.

INTERVENTIONS AND OUTCOME

The patient received 7 days intravenous and followed by 7 days oral antibiotic treatment, which lead to clinical improvement of his urinary tract infection. No pharmacological treatment was initiated for the asymptomatic and localized PDB. The patient was discharged under stable condition afterward.

LESSONS

In patients with mixed osteolytic and blastic lesions, the differential diagnoses include metabolic and metastatic bone disease. Thorough understanding of the morphology of the bone lesions in high risk patient, not only helps to make differential diagnosis, but it also leads to precise treatment and better outcome.

Intense 68Ga-PSMA Uptake in Diverticulum of the Sigmoid Colon

We present a case of a diverticulum of the sigmoid colon with intense prostate-specific membrane antigen (PSMA) activity on Ga-PSMA PET/CT. CT scan and colonoscopy showed no signs of inflammation or malignancy. This case presents an addition to the collection of benign pitfalls when reporting PSMA PET/CT; however, a Ga-PSMA up-taking focus in the colon should always cause further examination, as malignant etiology must be ruled out.

Imaging of Nonprostate Cancers Using PSMA-Targeted Radiotracers: Rationale, Current State of the Field, and a Call to Arms

Prostate-specific membrane antigen (PSMA) is a type II transmembrane glycoprotein that is highly overexpressed on prostate cancer epithelial cells and for which there is a growing body of literature examining the role of small-molecule and antibody radiotracers targeted against this protein for prostate cancer detection and therapy. Despite its name, PSMA is also expressed, to varying degrees, in the neovasculature of a wide variety of nonprostate cancers; indeed, the pathology literature is replete with promising immunohistochemistry findings. Several groups have begun to correlate those pathology-level results with in vivo imaging and therapy in nonprostate cancers using the same PSMA-targeted agents that have been so successful in prostate cancer. The potential to leverage radiotracers targeted to PSMA beyond prostate cancer is a promising approach for many cancers, and PSMA-targeted agents may be able to supplement or fill gaps left by other agents. However, to date, most of the reported findings with PSMA-targeted radiotracers in nonprostate malignancies have been in case reports and small case series, and the field must adopt a more thorough approach to the design and execution of larger prospective trials to realize the potential of these promising agents outside prostate cancer.

Comparison of hybrid 68Ga-PSMA-PET/CT and 99mTc-DPD-SPECT/CT for the detection of bone metastases in prostate cancer patients: Additional value of morphologic information from low dose CT

PURPOSE

This study compared ⁶⁸Gallium-prostate-specific-membrane-antigen based Positron-emission-tomography (⁶⁸Ga-PSMA-PET) and ^99metastabletechnetium-3,3-diphospho-1,2-propanedicarbonacid (^99mTc-DPD-SPECT) in performing skeletal staging in prostate cancer (PC) patients and evaluated the additional value of the information from low-dose-computed tomography (CT).

MATERIALS AND METHODS

In this retrospective study, 54 patients who received ⁶⁸Ga-PSMA-PET/CT and ^99mTc-DPD-SPECT/CT within 80 days were extracted from our database. Osseous lesions were classified as benign, malignant or equivocal. Lesion, region and patient based analysis was performed with and without CT fusion. The reference standard was generated by defining a best valuable comparator (BVC) containing information from all available data.

RESULTS

In the patient based analysis, accuracies measured as "area-under-the-curve" (AUC) for ⁶⁸Ga-PSMA-PET, ^99mTc-SPECT, ⁶⁸Ga-PSMA-PET/CT and ^99mTc-SPECT/CT were 0.97-0.96, 0.86-0.83, 1.00 and 0.83, respectively (p<0.05) (ranges = optimistic vs. pessimistic view). Region based analysis resulted in the following sensitivities and specificities: 91.8-97.7%, 100-99.5% (PET); 61.2-70.6%, 99.8-98.3% (SPECT); 97.7%, 100% (PET/CT), 69.4% and 98.3% (SPECT/CT) (p<0.05). The amount of correct classifications of equivocal lesions by CT was significantly higher in PET (100%) compared to SPECT (52.4%) (p<0.05).

CONCLUSION

⁶⁸Ga-PSMA-PET outperforms ^99mTc-DPD-SPECT in detecting bone metastases in PC patients. Additional information from low-dose-CT resulted in a significant reduction in equivocal lesions in both modalities, however ⁶⁸Ga-PSMA-PET benefited most.

KEY POINTS

• Ga-PSMA-PET outperforms ^99m Tc-DPD-SPECT in skeletal staging in prostate cancer patients • Proportion of equivocal decisions was significantly reduced by CT-fusion in both modalities • Ga-PSMA-PET benefits more from CT information, compared to ^99m Tc-DPD-SPECT.